•/* 


' 


THE  PH 
DIA 


TH 
DIAR7I 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


SG  LIST, 

OOK, 


LIST, 

)R    1854, 


Containing  i  la  pages  for  each 

month ;  pages  for  Obstetric  Engagements,  for  Vaccination  Engagements,  and  for 
accounts  asked  for  and  delivered. 

It  is  an  invaluable  pocket  companion  for  every  physician :  compact,  easily  carried 
in  the  pocket,  methodical  in  its  arrangement,  and  so  useful  that  the  physician,  once 
using  it,  will  never  afterwards  be  without  it. 


Price,  prepared  for  twenty-five  patients  weekly,  plain, 
Do.  do.  do.  tucks, 

Do.  fifty  do.  plain, 

Do.  do.  do.  tucks, 


50  cents. 
75      " 
75      " 
$1  00 


"Messrs.  Lindsay  and  Blakiston  have  laid  the  Profession  under  great  obligations 
for  one  of  the  greatest  conveniences  ever  furnished  them.  Here  is  a  little  pocket- 
book,  half  an  inch  thick,  six  by  three  in  dimensions,  which  will  hold  all  memoranda 
of  visits  paid  and  to  be  paid  for  each  day  of  each  month  during  the  year ;  of  ob- 
stetrical engagements;  things  wanted  and  lent;  the  addresses  of  patients  and 
nurses ;  bills  and  accounts  asked  for,  &c.  &c.  With  it  in  one's  pocket,  everybody's 
bill  can  be  made  out  in  a  few  minutes.  It  is  the  most  complete  thing  we  ever  saw, 
and  every  practitioner  would  secure  one  if  he  could  see  it." — Stethoscopist. 

The  above  work  was  commenced  in  1852,  and  has  met  with  such  universal  favor 
from  the  Profession,  that  it  is  considered  superfluous  to  say  more  to  those  who  have 
not  yet  had  one.  GIVE  IT  A  TRIAL. 

LINDSAY  &  BLAKISTON, 

Publishers  and  Booksellers, 

No*  35  South  Sixth  Street)  above  Chestnut* 


AT  THE  ANNEXED  PRICES^  ANY  OF  THE  FOLLOWING  WORKS 


MEDICAL. 

VELPEAU'S  ILLUSTRATED  MIDWIFERY.  Fifth  American  from  the  last 
French  edition,  with  numerous  additions  and  illustrations,  by  Prof.  C.  D. 
Meigs  and  W.  Byrd  Page,  M.D.  8vo.,  sheep,  .  .  .  .  $3  50 

CAZEAUX'S  MIDWIFERY,  including  the  Diseases  of  Pregnancy  and  Partu- 
rition.    116  illustrations.     8vo.,  sheep,     .  .  .  .  .     3  00 
13T  This  work   has   received   the   almost  universal  commendation  of  the 

Medical  Press  and  Profession  of  this  country. 

CRAIGE'S  GENERAL  AND  PATHOLOGICAL  ANATOMY.     Royal  8vo.,    .     3  00 
MEIGS'    PRACTICAL   TREATISE  ON   THE  DISEASES  OF  CHILDREN. 

Second  edition,  much  enlarged.     8vo.,  sheep,        .  .  .  .     3  00 

MENDENHALL'S  MEDICAL  STUDENTS'  VADE-MECUM.  Being  a  Com- 
pendium of  Anatomy,  Surgery,  the  Practice  of  Medicine,  &c.,  &c.  The 
Third  edition,  enlarged,  with  numerous  illustrations.  Royal  I2mo  ,  2  50 

WALTON'S  OPERATIVE  OPHTHALMIC  SURGERY.  167  illustrations.  8vo.,     3  00 
HEADLAND'S  TREATISE  ON  THE  ACTION  OF  MEDICINES   IN   THE 

SYSTEM.     8vo.,     .  . 1  50 

THE  PHYSICIAN'S  VISITING  LIST,  DAY-BOOK,  AND  MEMORANDA, 
published  each  year,  for  twenty-five  patients.  Cloth,  50  cents ;  tucks, 
75 ;  pencils,  75.  Ditto,  for  fifty  patients.  Cloth,  75  cents ;  tucks,  .  1  00 
A  GERMAN  ENGLISH  AND  ENGLISH-GERMAN  CLINICAL  PHRASE- 
BOOK  ;  or,  Conversation  between  Physician  and  Patient,  intended  for 
Hospital,  Dispensary,  and  Private  Practice.  By  Montgomery  Johns, 

M.D.     18mo  , 1  25 

HENLE'S  TREATISE  ON  GENERAL  PATHOLOGY.     Translated  by  H.  C. 

Preston,  M.D.     1  vol.,  8vo.,  .  .  .  .  .  .     2  00 

STILLE'S  ELEMENTS  OF  GENERAL  PATHOLOGY.     1  vol.,         .            .     1  60 
TUCKER'S  PRINCIPLES  AND  PRACTICE  OF  MIDWIFERY,        .            .     1  50 
EARTH  AND  ROGERS'S  MANUAL  OF  AUSCULTATION  AND  PERCUS- 
SION,           63 

REESE'S  ANALYSIS  OF  PHYSIOLOGY.     A  new  and  enlarged  edition,      .     1  50 
MURPHY'S  KEVIEW  OF  CHEMISTRY  FOR  STUDENTS,  .  .  .     1  00 

BIDDLE'S  REVIEW  OF  MATERIA  MEDICA  AND  THERAPEUTICS,  FOR 

STUDENTS      With  illustrations.     Cloth,  .  .  .  .     1  00 

HASTINGS'   MINOR  SURGERY;   the  Application  of  Dressings,   &c.,   &c. 

With  143  illustrations.     Cloth,  $1  38.     Sheep,    .  .  .  .     1  50 

MACKINTOSH'S  PRACTICE  OF  MEDICINE.     By  Morton.     Third  edition,     3  00 

LECTURES  ON  YELLOW  FEVER.     Cloth, 50 

COXE'S  EPITOME  OF  HIPPOCRATES  AND  GALEN.     8vo.,  sheep,          .     2  00 
MORRIS'S  LECTURES  ON  SCARLLT  FEVER.     1  vol.,  8vo.,  cloth,  .         75 

SIMPSON    ON   THE    USES    OF   CHLOROFORM   AND   ETHER  IN  SUR- 
GERY, MIDWIFERY,  &c.     1  vol.,  8vo.,  cloth,    .  .  .  .     1  25 
COMFORT'S  THOMSONIAN  PRACTICE  OF  MEDICINE.     4th  ed.     8vo.,      300 

PHARMACEUTICAL. 

REESE'S   AMERICAN    MEDICAL   FORMULARY,  including  the   Medical 

Properties  and  Uses  of  Medicine.     Cloth,  $1  38.     Sheep,  .  .150 

BEASLEY'S  DRCGGIST'8  GENERAL  RECEIPT-BOOK  AND  VETERI- 
NARY FORMULARY  Cloth,  $1  38.  Sheep,  .  .  .  .  1  50 

BEASLEY'S  FORMULARY:  A  Companion  to  the  Druggist's  Receipt-Book 

and  Synopsis  of  the  British  and  Foreign  Pharmacopoeias.     Cloth,  .     1  38 

Ditto,  sheep,    .  .  .  .  .  .  .  .     1  60 

THE  PHYSICIAN'S  POCKET  PRESCRIPTION-BOOK,  containing  Lists  of 

Terms,  Phrases,  Abbreviations,  £c.,  &c.    Cloth,  63  cents     Ditto,  tucks,         80 

WYTHE'S  POCKET  DOSE  AND  SYMPTOM  BOOK.  Cloth,  63  cts    Do,  tucks,         80 

THE  AMERICAN  JOURNAL  OF  PHARMACY.     Published  by  authority  of 

the  Philadelphia  College  of  Pharmacy.     6  numbers.     Per  annum,          .     3  00 

PERIODICALS. 

BANKING'S  HALF-YEARLY  ABSTRACT  OF  THE  MEDICAL  SCIENCES. 

8  volumes,  sheep,  per  vol.,  $2  00.     16  numbers,  paper,  per  no.,  .         75 

Published  half-yearly,  in  February  and  August,  per  annum,       .  .     2  00 

To  mail  subscribers,  postage  prepaid,  when  paid  for  in  advance. 

THE    BRITISH    AND    FOREIGN    MEDICAL   REVIEW.     London   edition. 

Quarterly.     Per  annum,    .  .  .  .  .  .  .     5  00 

LINDSAY  &  BLAKISTON,  PUBLISHERS,  PHILADELPHIA. 


WILL  BE  SENT,   POSTAGE  FREE,  BT  MAIL. 


THE  MEDICAL  EXAMINER,  AND  RECORD  OF  MEDICAL  SCIENCE. 
Edited  by  Francis  Gurney  Smith,  M.D.,  and  J.  B.  Biddle,  M.D.  Pub- 
lished monthly.  Per  annum,  .  .  .  .  .  .  $3  00 


FOR  FAMILIES,  &c. 


SMITH'S  DOMESTIC  MEDICINE,  SURGERY,  AND  MATERIA  MEDICA. 

With  Rules  for  Diet,  Bathing,  the  Management  of  the  Sick-Room,  &c.,     1  25 
THE  FAMILY  AND  SHIP  MEDICINE  CHEST  COMPANION.     With  Rules 

for  the  Compounding  and  Administering  Medicines,  &c.,  &c.  Royal  12mo.,     1  60 
TILT'S    ELEMENTS    OF    HEALTH    AND    PRINCIPLES    OF    FEMALE 

HYGIENE.     1  vol.,  royal  12mo.,  .  .  .  .  .     1  25 

BULL  ON  THE  MATERNAL  MANAGEMENT  OF  CHILDREN  IN  HEALTH 

AND  DISEASE.     A  new  and  improved  edition.     12mo.,  cloth,  .  .     1  00 

MAYO'S  PHILOSOPHY  OF  LIVING.     From  the  3d  Lond.  ed.     12mo.,  cloth,         75 
This  is  the  most  thorough  treatise  on  the  various  temperaments,  food, 
drink,   exercise,  sleep,   bathing,  dress,  &c. ;   and  along  with  sound 
directions  for  preserving  physical  health  of  the  mind,  which  deserves 
especial  attention. 

DENTAL. 

HARRIS'S  DICTIONARY  OF  DENTAL  SURGERY  AND  MEDICAL  TER- 
MINOLOGY. A  royal  8vo.  volume,  sheep,  .  .  .  .  6  00 

HARRIS'S  PRINCIPLES  AND  PRACTICE  OF  DENTAL  SURGERY.  Fifth 

edition,  greatly  enlarged  and  improved,  with  over  200  illustrations.  8vo  ,  4  00 

JOURDAIN'S  DISEASES  AND  SURGICAL  OPERATIONS  OF  THE 

MOUTH.  With  illustrations.  8vo.,  sheep,  .  .  .  .  2  50 

BOND'S  PRACTICAL  TREATISE  ON  DENTAL  MEDICINE,  as  connected 

with  the  study  of  Dental  Surgery.  2d  edition,  enlarged  8vo.,  sheep,  .  2  50 

PIGGOTT'S  DENTAL  CHEMISTRY  AND  METALLURGY,  .  .     2  50 

FLAGG  ON  ETHER  AND  CHLOROFORM  IN  SURGERY,  DENTISTRY, 

MIDWIFERY,  THERAPEUTICS,  &c.,  &c.  12mo.,  cloth,  .  .  75 

ARTHUR'S  MANUAL  OF  DISEASES  OF  THE  TEETH.    With  illustrations,         50 

HORNER'S  STUDENTS'  GUIDE  IN  EXTRACTING  TEETH.     12mo.,  cloth,         50 

TOME'S  DENTAL  PHYSIOLOGY  AND  SURGERY.  With  illustrations. 

8vo  ,  cloth,  .  .  .  .  .  .  .  .  .  3  50 

THE  AMERICAN  JOURNAL  OF  DENTAL  SCIENCE.  Edited  by  C  A. 

Harris,  M.D.,  and  A.  A.  Blandy,  M.D.  Published  quarterly.  Per  annum,  5  00 

SCIENTIFIC. 

MORFIT'S    CHEMICAL    AND    PHARMACEUTICAL    MANIPULATIONS. 

With  423  illustrations.  8vo.,  cloth,  $1  75.  Ditto,  sheep,  .  .  2  00 

NOAD'S  CHEMICAL  ANALYSIS,  QUANTITATIVE  AND  QUALITATIVE. 

With  additions  by  Campbell  Morfit,  and  numerous  illustrations.     8vo., 

cloth,  $1    50.     Ditto,  sheep,  .  .  .  .  .  .     1  75 

WYTHE'S  MICROSCOPIST'S  MANUAL;  for  Students  and  Others.  With 

numerous  illustrations.  Second  edition,  enlarged,  .  .  .  1  25 

WYTHE'S  CURIOSITIES  OF  THE  MICROSCOPE.  Beautifully  illustrated 

with  colored  and  other  plates,        .  .  .  .  .  .     1  00 

DE  BOISMONT'S  RATIONAL  HISTORY  OF  HALLUCINATIONS,  APPA- 
RITIONS, VISIONS.  &c.  From  the  last  French  edition.  8vo.,  .  2  50 
MAYO'S  POPULAR  SUPERSTITIONS,  AND  THE  TRUTHS  CONTAINED 

THEREIN.  With  an  Account  of  Mesmerism.  12mo.,  cloth,  ,  .  75 

GOD  IN  DISEASE;  or  the  Manifestation  of  Design  in  Morbid  Phenomena. 

By  J.  F   Duncan.     12mo.,  cloth,   ......         76 

WALKER  ON  INTERMARRIAGE;  its  Influence  on  Beauty,  Health,  and 

Intellect  A  new  edition,  with  eight  illustrations.  J2mo.,  cloth,  .  75 

WRIGHT'S  AMERICAN  RECEIPT-BOOK;  containing  3000  Receipts  in  all 

the  Useful  and  Domestic  Arts  12mo  ,  cloth,  .  .  .  .100 

OVERMAN'S  PRACTICAL  MINERALOGY,  ASSAYING,  AND  MINING. 

12mo.,  cloth,  ........        76 

MANURES ;  their  Composition,  Preparation,  and  Action  upon  Soils.  18mo., 

doth,  .........         25 

DARLINGTON'S  FLORA  CESTRICA,  or,  Botanizing  Companion.  Royal 

12mo.,          .  -  .  .  .  .  .  .  .     2  00 

COULTAS'S  PRINCIPLES  OF  BOTANY,  AS  EXEMPLIFIED  IN  THE 

CRi'PTOGAMlA.     With  illustrations, 60 

GENERAL  CATALOGUES  SENT  GRATIS  BY  APPLICATION, 


. — % 

LINDSAY  AND  BLAKISTOft, 
PUBLISHERS   AND   BOOKSELLERS. 

No.  25  South  Sixth  Street,  above  Chestnut, 
Give  Special  Attention  to  the  MEDICAL  BRANCH  of  their  Business, 

KEEPING   ALWAYS    ON   HAND, 

IN  ADDITION  TO  THEIR  OWN  PUBLICATIONS, 

A  LARGE  AND  FULL  ASSORTMENT  OF 

MEDICAL,  SURGICAL,  DENTAL,  AND  SCIENTIFIC  BOOKS, 

INCLUDING  ALL  PUBLISHED  IN  THE  UNITED  STATES, 

Which  they  Sell  at  the  very  Lowest  Prices. 

ALSO, 

HAVING   AN   AGENCY  IN   LONDON, 
THEY    RECEIVE    MONTHLY    PACKAGES 

CONTAINING    ALL 

NEW  BOOKS  AND  PERIODICALS, 

AND  IMPORT  TO  ORDER  AT  THE  LOWEST  RATES 

ENGLISH,  FRENCH,  AND  GERMAN  WORKS. 

THEY   ALS(5  RECEIVE    SUBSCRIPTIONS    FOR 

ALL    AMERICAN    OR    FOREIGN 

MEDICAL    PERIODICALS. 

Particular  attention  will  he  given  to  the  faithful  execution  of  all  orders  intrusted 
to  them,  which  they  will  guarantee  shall  be  furnished  at  the  very  lowest  prices. 

All  of  the  Publications  of  H.  Bailliere,  of  London  and  New  York,  on  hand,  or 
furnished  at  his  prices. 

LINDSAY  &  BLAKISTON, 

PUBLISHERS,  BOOKSELLERS,  AND  BOOKBINDERS, 

No*  25  South  Sixth  Street,  above  Chestnut. 


A  TEXT  BOOK 


OP 


ANATOMY, 


AND 


GUIDE  IN  DISSECTIONS, 


FOR    THE    USE    OF 


STUDENTS  OF  MEDICINE  AND  DENTAL  SURGERY. 


BY 


WASHINGTON  K.  HANDY,  M.  D. 

PROFESSOR  OP  ANATOMY  AND  PHYSIOLOGY   IN  THE   BALTIMORE   COLLEGE    OF  DENTAL  8TTRG2RY  ;  LATE 
PROFESSOR  OF  ANATOMY  AND  OPERATIVE  SURGERY  IN  WASHINGTON  UNIVERSITY,  BA_LTIiIOKK.» 


WITH  TWO  HUNDRED  AND  SIXTY-FOUR  ILLUSTRATIONS. 


PHILADELPHIA: 
LINDSAY    &    BLAKISTON 

1854. 


30794 


Entered,  according  to  act  of  Corgress,  in  the  year  1853, 

BY  LINDSAY  AND  BLAKISTON, 
In  the  Clerk's  Office  of  the  District  Court  for  the  Eastern  District  of  Pennsylvania. 


fr«m 


SHEBWOOD  &  Co.,  PEINTERS, 

BALTIMORE. 


TO 

CHAPIN   A.    HARRIS,   M.D. 

PEOFESSOE  OF  THE  PBINCIPLES  OF  DENTAL  SUEGEEY  IN  THE  BALTIMORE  COLLEGE, 

AS     AN     ACKNOWLEDGMENT     FOR 
UNTIRING  DEVOTION  IN  THE  ADVANCEMENT  OF  DENTAL  SCIENCE, 

AND     AS     A 
TESTIMONIAL    OF    REGARD    FOR    GREAT    PRIVATE    WORTH, 

THIS   WORK 

IS  RESPECTFULLY  INSCRIBED, 

BY    HIS    GRATEFUL    FRIEND, 

THE    AUTHOR. 


PREFACE. 


THE  author  is  aware  of  the  many  valuable  works  on 
Anatomy  adapted  to  the  Student  and  Practitioner  of  Medi- 
cine; but  he  does  not  know  of  one  that  has  been  arranged 
with  a  view  also  to  the  claims  of  the  Student  and  Practi- 
tioner of  Dental  Surgery.  To  prepare  a  work,  therefore, 
adapted  alike  for  the  Dental  as  well  as  the  Medical  Stu- 
dent— one  which  directs  special  attention  to  the  Mouth, 
showing  step  by  step  the  important  anatomical  and  physi- 
ological relations  which  it  has  with  each  and  all  the 
organs  and  functions  of  the  general  system — forms  one  of 
the  leading  objects  of  the  present  undertaking. 

Dental  Students  are  slow  to  see  and  feel  the  necessity  of 
a  knowledge  of  any  more  of  Anatomy  than  so  far  as  the 
Teeth  and  their  immediate  connections  in  the  mouth  are 
concerned,  and  to  go  beyond  this  is  thought  rather  a  waste 
of  time,  and  entirely  foreign  to  the  practice  of  the  profes- 
sion they  design  to  pursue.  No  work  on  Anatomy  has 
taken  very  particular  pains  to  teach  them  any  better.  To 
correct  this  false  and  dangerous  sentiment,  and  to  demon- 
strate the  necessity  of  anatomical  knowledge  to  the  scien- 
tific, skillful,  and  successful  Dentist,  equally  with  that  of 
the  Physician,  forms  the  second  and  chief  reason  which 
has  induced  the  author  to  write  the  present  work. 

The  Plan  of  the  work,  after  giving  a  general  outline  of 
Organization,  divides  the  subject  into  four  parts: 

The  first  part  teaches  the  Alphabet  of  Anatomy,  or  the 
Elementary  Tissues  of  the  Body,  whose  varied  combina- 


VI  PREFACE. 

tion  constitutes  the  Anatomical  Language,  or  the  various 
organs  composing  the  General  System. 

The  second  part  begins  with  the  Head,  and  describes  its 
organs,  as  far  as  possible,  in  their  functional  order  and 
dependency;  thus  combining  the  Anatomy  and  Physiology 
of  the  several  organs,  however  various,  concerned  in  any 
particular  function — a  plan  found  to  be  most  interesting? 
and,  it  is  believed,  at  the  same  time  most  practical  and 
useful.  This  part  is  then  made  complete  by  showing  the 
Anatomical  and  Physiological  relations  of  the  Mouth  with 
the  different  parts  of  the  Head. 

The  third  part,,  embracing  the  Trunk,  is  examined  in 
the  same  physiological  order,  and  completed  in  the  same 
manner,  by  demonstrating  the  Eelations  of  the  Mouth  with 
its  several  organs,  viscera  and  functions. 

The  fourth  part  comprises  the  Extremities,  which  do  not 
admit  of  the  same  kind  of  arrangement  so  readily,  and  are 
demonstrated  in  the  ordinary  way. 

The  author  has  freely  consulted  the  best  sources  of 
authority,  and  here  desires  to  make  his  acknowledgments 
to  the  works  of  Wistar  by  Pancoast,  Homer,  Smith's  Ana- 
tomical Atlas,  Bell  by  Godman,  Quain,  Wilson,  Sharpy 
and  Quain  by  Leidy,  Cloquet,  Cruveilheir  by  Pattison,  Von 
Behr's  Hand  Book  of  Human  Anatomy,  The  Dublin  Dis- 
sector, Solly  on  the  Human  Brain,  Knox's  Manual  of 
Anatomy,  Holden's  Manual  of  Dissections,  Morton's  Hu- 
man Anatomy,  Nasmyth,  Goodsir,  Owen,  Harris,  Tomes, 
Carpenter's  Human  Physiology,  Carpenter's  Principles  of 
General  and  Comparative  Physiology,  Muller  by  Bell, 
Magendie;  and  most  especially  does  he  return  his  thanks 
to  Professors  Harris  and  Piggot  for  their  kind  assistance 
and  valuable  suggestions,  while  the  work  was  passing 
through  the  press. 


PREFACE.  VII 

The  Index,  it  will  be  perceived,  has  been  arranged  some- 
what differently  from  the  one  in  common  use,  that  is  to 
say,  instead  of  finding  all  the  bones  arranged  under  the 
one  head  of  bones,  muscles  under  the  one  head  of  muscles, 
arteries  under  the  one  head  of  arteries,  &c.,  each  bone, 
muscle,  artery,  &c.,  will  be  found  under  its  proper  alpha- 
betical head. 

W.  K.  HANDY. 

BALTIMORE,  OCT.  19,  1853. 


CONTENTS. 


INTRODUCTION. 

PAGB 

HISTORY  OF  ANATOMY,.-    > 33 

GENERAL  RULES  FOR  CONDUCTING  DISSECTIONS, 40 

ORGANIZATION, 41 

ANALYSIS  OF  ORGANIZATION — 

a  Organ— it3  Definition— Function,. 41 

6  Apparatus, 41 

c  System, 41 

d  Organization— how  defined, 41 

FUNDAMENTAL  ELEMENTS  FORMING  ORGANIZATION — 

1.  A  Definite  Origin  or  Generation, 42 

2.  A  Definite  Form, 43 

3.  A  Definite  Size, 43 

4.  A  Definite  and  Peculiar  Structure, 43 

5.  A  Nutritive  Fluid, 44 

6.  A  Definite  Nutrition, 44 

7.  A  Dependency  among  the  several  Organs,. 44 

8.  A  Limited  Duration, 45 

FUNDAMENTAL  ELEMENTS  PRESERVING  ORGANIZATION — 

1.  Atmospheric  Air, 45 

2.  Food 45 

3.  Water, 45 

4.  Heat, 45 

RELATIONS   BETWEEN  THE   ABOVE  CLASSES  OF  ELEMENTS   FIXED   AND 

DETERMINED, 46 

Obedience  to  which  being  rewarded  with  Health  and  Integrity  of 

Organization , 46 

Disobedience  with  Disease  and  Death, 46 

VARIETIES  IN  ORGANIZATION, 47 

Two  great  divisions—I.  Vegetable, 41 

2.  Animal 47 

VARIETIES  IN  ANIMAL  KINGDOM — 

1.  Radiata— Zoophytes, 47 

2.  Articulata — Worms,  Insects, 47 

3.  Mollusca— Shell  Fish, 47 

4.  Vertebrata, 48 

These  varieties  are  so  many  types  of  different  Organizations,  and  de- 
pend on  many  circumstances;  for  example,  the  Vertebrata  are 
formed  with  special  reference  to  one  or  more  of  the  fundamental 
elements  of  preservation;  as 

Fish  are  formed  with  reference  to  the  Water,  their  special  element,. .  48 
Birds  are  formed  with  reference  to  the  Air, 48 


X  CONTENTS. 

Reptiles  to  both  Air  and  Water. " 48 

Herbiverous  Animals  to  special  kinds  of  food;  as  Grass,  Grain,  Fruit,  &c.  49 

Carnivorous  Animals  to  Flesh, , 49 

SOME  ORGANIZATIONS  ARE  FORMED  WITH  REFERENCE  TO  CLIMATE;  as 

The  Polar  Bear  for  a  Cold  Climate, 49 

The  Ourang-Outang  for  a  WarmC'limate, 49 

This  preference  to  Climate,  and  to  one  or  more  of  the  fundamental  ele- 
ments, Air,  Water,  Food,  &c.,  constitutes  so  many  Special  Laws  of 
their  Being  and  Existence.         .-..  ,.  ,  , 
THE  LAST  VARIETY  OF  ORGANIZATION  is  MAN,  formed  with  reference  to 

his  Intellectual  and  Moral  Faculties, 50 

CONSTITUENTS  OF  HUMAN  ORGANIZATION, 50 

1.  Chemical, 50 

2.  Organic, 50 

Chemical— Oxygen,  Hydrogen,  Carbon,  Nitrogen, 50 

,  Phosphorus,  Lime,  &c., 50 

Organic — Protein,  Albumen,  Gelatin,  Fibrin,  Mucus,  &c., 52 

Union  of  these  Elements  constitutes  the  Solids  and  Fluids  of  the  Body. 
ALL  ORGANIZATIONS  FORMED  AND  COMPLEX,  in  proportion  to  the  num- 
ber and  variety  of  the  Powers,  Properties  and  Functions  they 

possess, 50 

Man  having  most  Functions,  consequently  most  complicated, 50 

DEVELOPMENT  OF  ORGANIZATION, 57 

By  Steps, , 57 

TABLE  OF  POINTS  OF  DIFFERENCE  BETWEEN  INORGANIC  AND  ORGANIC  BODIES, 

as  given  by  M.  Magendie, 57 

ANATOMY — its  Divisions, 58 

PART  FIRST. 

ALPHABET  OF  ANATOMY,  OR  ELEMENTARY  TISSUES, 61 

CHAPTER  FIRST. 

ORIGIN  OF  TISSUES, 63 

From  the  simple  Cell  or  Vesicle  discovered  by  Schwann  in  1838, ...  63 

Development  of  Tissues, 64 

PHYSICAL  PROPERTIES  OF  THE  TISSUES,..  , . . . . 65 

VITAL  PROPERTIES  OF  THE  TISSUES, 65 

NUMBER  OF  TISSUES, >. . . . f)6 

CHAPTF.R  SECOND. 
THE  BLOOD, 66 

CHAPTER  THIRD. 

THE  CELLULAR  TISSUE, 75 

Adipose, 79 

Serous, , 80 


•j      CONTENTS.  XI 

Synovial,.. ." 82 

Bursae  Mucosae,. 82 

CHAPTER  THIRD. 

THE  VASCULAR  TISSUE, 83 

Arterial, 94 

Venous, 99 

Lymphatic 105 

CHAPTER  FOURTH. 

THE  NERVOUS  TISSUE, 106 

Animal  Life, 106 

Organic  Life, 106 

CHAPTER  FIFTH. 
GLANDULAR  TISSUE, t 117 

CHAPTER  SIXTH. 

CUTANEOUS  TISSUE, 123 

External  or  Skin, 123 

Internal  or  Mucous  Membrane, 123 

CHAPTER  SEVENTH. 

MUSCULAR  TISSUE, 141 

Voluntary, 142 

Involuntary, 142 

CHAPTER  EIGHTH. 

FIBROUS  TISSUE, ; 148 

Ligaments, 150 

Tendons, 153 

Fibrous  Envelopes, 154 

CHAPTER  NINTH. 
CARTILAGINOUS  TISSUE, 156 

CHAPTER  TENTH. 
FIBRO-CAIITILAGINOUS  TISSUE, ~. 159 

CHAPTER  ELEVENTH. 
ERECTILE  TISSUE, 160 

CHAPTER  TWELFTH. 
OSSEOUS  TISSUE, 161 


XH  CONTENTS. 

PART    SECOND. 

THE    HEAD. 

CHAPTER  FIRST. 

PASSIVE  ORGANS  OF  THE  HEAD,  BONES — 

1 .  Cranium, 177 

2.  Face, 196 

SECTION  I. 
BONES  OF  CRANIUM — 

Frontal, 177 

Parietal, 180 

Occipital, 182 

Temporal , 184 

Ethmoid, 189 

Sphenoid, 192 

General  Remarks  on  the  Cranium, 195 

SECTION  II. 
BONES  OF  THE  FACE — 

Superior  Maxillary, , 196 

Palate 203 

Malar, 205 

Lachrymal, 206 

Nasal, 207 

Inferior  Turbinated, 208 

Vomer, 208 

Inferior  Maxillary, 209 

Articulation  of  the  Lower  Jaw, 213 

General  Remarks  on  the  Skull, 215 

CHAPTER  SECOND. 

ACTIVE  ORGANS  OF  THE  HEAD, 222 

1.  Organs  of  Digestion, 222 

2.  Organs  of  Expression  and  Speech, 222 

3.  Organs  of  Sense, 222 

External 331 

Internal, 386 

4.  Organs  of  Circulation 222 

5.  The  Fascia, 222 

'  ORGANS  OF  DIGESTION  include  those  of  Prehension,  Mastication,  Insaliva- 

tion  and  Deglutition,  and  belong  to  the  Jtfouth. 

SECTION  I. 

ORGANS  OF  PREHENSION — Mode  of  Dissection, 223 

Levator  Labii  Superioris  Alaeque  Nasi, 224 

Depressor  Labii  Superioris  Alaeque  Nasi, 224 

Levator  Anguli  Oris, 224 


CONTENTS. 

Depressor  Anguli  Oris,.. •  224 

Levator  Labii  Inferioris, 225 

Depressor  Labii  Inferioris, 225 

Zygomaticus  Major, 225 

Zygomaticus  Minor, 225 

Buccinator, 225 

Orbicularis  Oris, 226 

Combined  Action  of  Muscles, 226 

Blood  Vessels, 226 

Nerves,....* 227 

SECTION  II. 

ORGANS  OF  MASTICATION, 227 

PASSIVE  ORGANS  OF  MASTICATION — 

The  Teeth, 227 

Division  into  Temporary  and  Permanent, 228 

Classification, 228 

1.  Incisors, 229 

2.  Cuspid  or  Canine, 230 

3.  Bicuspid, 232 

4.  Molar, 232 

Description  general  of  a  Tooth, 229 

Description  of  each  Class  of  Teeth, 229 

Microscopic  Anatomy  of  the  Pulp, 236 

Eruption  of  Temporary  Teeth, ,  244 

Eruption  of  Permanent  Teeth, 245 

Differences  between  Temporary  and  Permanent  Teeth, 246 

Differences  between  the  Teeth  and  Bone, 247 

Irregularities  of  the  Teeth, 247 

SECTION  III. 

ORIGIN  AND  DEVELOPMENT  OF  THE  TEETH, 248 

FORMATION  OF  THE  ENAMEL, 253 

CHANGES  PRODUCED  IN  THE  UPPER  AND  LOWER  JAW,  OR  FACE,  FROM  DE- 
VELOPMENT OF  THE  TEETH, 255 

THE  FUNCTIONAL  RELATIONS  OF  THE  TEETH, 258 

VARIETIES  OF  TEETH, , 258 

SECTION  IV. 

BLOOD-VESSELS  OF  THE  TEETH, 259 

NERVES  OF  THE  TEETH 262 

SECTION  V. 

COMPARATIVE  ANATOMY  OF  THE  TEETH, 268 

EXTENT  OF  DENTAL  ORGANS  IN  ANIMAL  KINGDOM — GENERAL  REMARKS  ON 
DIFFERENT  CLASSES — 

First  Class— Mammalia, 270 

Quadrumana, 273 

Insectivora, 278 


XIV  CONTENTS. 

Cheiroptera, 279 

Carnivora, 280 

Marsupialia, 282 

Rodentia,.... 282 

Edentata, 283 

Pachydermata, 283 

Ruminantia, 288 

Cetacea, 289 

Second  Class— A ves, 289 

Third  Class— Reptilia, 290 

Fourth  Class— Pisces, 292 

Second  Division  of  Animal  Kingdom— The  Invertebrata, 293 

SECTION  VI. 

ACTIVE  ORGANS  OF  MASTICATION— Dissection,. 294 

Masseter  Muscle, 294 

Temporal, 295 

Pterygoideus  Externus 296 

Pterygoideus  Internus, 297 

Combined  Action  of  Muscles, 297 

Blood- Vessels, 298 

Nerves, 298 

SECTION  VII. 

ORGANS  OF  INSALIVATION, 298 

Dissection, 299 

Parotid  Gland, 299 

Sub-Maxillary  Gland 300 

Sub-Lingual  Gland, 301 

Blood-Vessels, 302 

Nerves 302 

SECTION  VIII. 

ORGANS  OF  DEGLUTITION, 303 

MUSCLES— Dissection, 303 

Digastricus, 304 

Mylo-Hyoideus, 304 

Genio-Hyoideus, 305 

Genio-Hyoglossus, 305 

Hyoglossus 306 

Styloglossus, 306 

Stylo- Hyoideus 306 

SOFT  PALATE— Velum  Pendulum  Palati 306 

Situation, 306 

Levator  Palati, 308 

Tensor  Palati,  or  Circumflexus, 308 

Constrictor  Isthmi  Faucium ,  or  Palato-Glossus, 309 

Palato-Pharyngeus, 309 

Azygos-Uvulae, 309 


CONTENTS.  XV 

Blood- Vessels, 309 

Nerves, 309 

THE  TONGUE, 310 

Papillae — Papillae  Maximse,  or  Circumvallatae, 311 

Papillae  Mediae,  or  Fungiformes, 311 

Papilla?  Villosse, 311 

Papilla  Filliformes, 311 

Styloglossus  Muscle, 306 

Hyoglossus, 306 

Genio-Hyoglossus, 305 

Lingualis, 313. 

Blood-Vessels  of  Tongue, 313 

Nerves  of  Tongue 314 

PHARYNX 314 

Situation , 314 

Dissection, .315 

Inferior  Constrictor, 316 

Middle  Constrictor, 316 

Superior  Constrictor  of  the  Pharynx, 316 

Stylo-Pharyngeus, 316 

Cavity  of  Pharynx, 317 

Blood- Vessels  of  Pharynx, 317 

Nerves  of  Pharynx, 318 

SECTION  IX. 

MOUTH, 318 

Cavity  of  Mouth — Boundaries, 318 

Organs  composing  it, 319 

Mucous  MEMBRANE  OF  MOUTH  AND  PHARYNX, 319 

THE  GUMS, 321 

ALVEOLO  DENTAL  PERIOSTEUM, 322 

BLOOD-VESSELS  OF  MOUTH  AND  PHARYNX, 323 

NERVES  OF  THE  MOUTH  AND  PHARYNX, 324 

CHAPTER  THIRD. 

ORGANS  OF  EXPRESSION, 324 

Dissection, 324 

Occipto-Frontalis  Muscle, 324 

Pyramidalis  Nasi, 325 

Corrugator  Supercilii, 325 

Compressor  Nasi, 325 

Orbicularis  Palpebrarum, 326 

Conjoint  Action  of  Muscles, 327 

Nerves— Portia-Dura  of  the  Seventh  Pair, 327 

Blood-Vessels, 330 

CHAPTER  FOURTH. 

ORGANS  OF  SENSE, 330 

External  or  Special  Sensation 331 


XVI  CONTENTS. 

The  Eye  for  seeing, 331 

The  Ear  for  hearing 331 

The  Tongue  for  tasting, 331 

The  Nose  for  smelling, 331 

The  Skin  for  touch, 331 

SECTION  I. 

THE  EYE, 331 

Division— 1.  Eye  proper,  or  Ball, 331 

2.  Appendages  of  the  Eye,  or  Tutamina  Oculi, 331 

Ball  of  the  Eye  consists  of  a  Membranous  Case  and  four  Refracting 

Media, 332 

MEMBRANES  OF  THE  EYE, 332 

1.  Sclerotic  Coat, 332 

2.  Choroid, 334 

3.  Retina, 339 

MEDIA  OF  THE  EYE, 340 

1.  Cornea, 340 

2.  Aqueous  Humor 342 

3.  Crystalline  Lens, 343 

4.  Vitreous  Humor, 345 

Summary  of  Blood-Vessels  and  Nerves  of  the  Ball  of  the  Eye,. . . .  346 

APPENDAGES  OF  THE  EYE, 349 

Muscles, 349 

Rectus  Superior, 349 

Rectus  Inferior, 350 

Rectus  Externus, 350 

Rectus  Internus, 350 

Obliquus  Superior, 350 

Obliquus  Inferior, 351 

Levator  Palpebrae  Superioris  and  Tensor  Tarsi, 351 

Nerves  of  the  Muscles  of  the  Eye, 352 

Eyebrows, 354 

Eyelids, 355 

Lachrymal  Apparatus, 358 

1.  Lachrymal  Gland, 358 

2.  Lachrymal  Ducts,...* 359 

3.  Lachrymal  Sac, 359 

BLOOD-VESSELS  OF  THE  EYE, 360 

NERVES  OF  THE  EYE, 360 

SECTION  II. 

THE  EAR, 360 

External, 361 

Middle, 361 

Internal  Ear, 361 

EXTERNAL  EAR, 361 

1.  Pinna, 361 

2.  Meatus  Externus, . .                                                              361 


CONTENTS.  XVII 

MIDDLE  EAR, 364 

1.  Membrana  Tympani, 364 

2.  Ossicula  Auditus,  or  Bones  of  the  Ear 368 

3.  Muscles  of  Tympanum 369 

INTERNAL  EAR,  OR  LABYRINTH. 370 

1 .  Vestibule, 370 

2.  Cochlea, 371 

3.  Semi-circular  Canals, 373 

Nerves  of  Ear, 375 

Blood-Vessels  of  Ear, 376 

General  Remarks, 377 

SECTION  III. 

THE  TONGUE,  Organ  of  Taste, 377 

Structure — see  Organs  of  Deglutition, 310 

Physiology  of  Taste, 379 

SECTION  IV. 
THE  NOSE,  Organ  of  Smell, 379 

1.  Cartilages, 380 

2.  Nasal  Fossae, 381 

3.  Pituitary  Membrane, 383 

4.  Blood-Vessels  of  Nose, 383 

5.  Nerves, 383 

SECTION  V. 

THE  SKIN,  Organ  of  Touch, 384 

Structure, 385 

Physiology  of  Touch, 386 

CHAPTER  FIFTH. 

INTERNAL  ORGANS  OF  SENSE, 386 

CEREBRO  SPINAL  Axis, 386 

Division — Dissection  from  below: 

1.  Spinal  Marrow, 387 

2.  Brain, 392 

SECTION  I. 

SPINAL  CORD, 387 

Situation, 387 

Membranes, 387 

Division  into  Rods  or  Columns, 390 

Nerves, 391 

SECTION  II. 

THE  BRAIN, 392 

Situation, 392 

Membranes,. 393 

2A 


CONTENTS. 


1.  Dura-Mater,  .............................................  393 

2.  Tunica  Arachnoidea,  .....................................  398 

3.  Pia  Mater,  .....................  .  ........................  399 

4.  Sinuses,  .................................................  396 

DIVISION  OF  THE  BRAIN,  ............................................  392 

1.  Medulla  Oblongata—  Situation,  .................................  400 

g  ....Divided  into—  Corpora  Pyramidalia,  ...........................  401 

Corpora  Olivaria,  ..............................  401 

Corpora  Restiformia,  ...........................  401 

Nerves,  ........................................  402 

2.  Pons  Varolii,  ................................................  402 

3.  Cerebellum,  .................................................  403 

Situation,  ................................................  403 

Surfaces,  ...................  .  .............................  404 

Structure,  ................................................  406 

4.  Cerebrum,  ...................................................  408 

Situation,  .................................................  408 

Surface,  ..................................................  408 

Divided  into  Hemispheres,  .................................  408 

Lobes,  ...................................................  408 

Nerves,  .......  .  ..........................................  420 

Blood-Vessels,  .............................................  425 

SECTION  III. 
BLOOD-VESSELS  OF  HEAD  IN  NUMERICAL  ORDER,  .........................  428 

SECTION  IV. 
TABLE  or  MUSCLES  OF  THE  HEAD,  ....................................  435 

CHAPTER  SIXTH. 

ANATOMICAL  AND  PHYSIOLOGICAL  RELATIONS  OF  THE  MOUTH  WITH  THE 
DIFFERENT  PARTS  or  THE  HEAD,  .......  .  ......................  ...  437 


PART  THIRD. 

THE  TRUNK— ITS  ORGANS,  ACTIVE  AND  PASSIVE. 

CHAPTER  FIRST. 

PASSIVE  ORGANS — THE  BONES, 443 

1.  Spine, 443 

2.  Thorax, 443 

3.  Pelvis, 443 

N. 

SECTION  I. 

SPINB,  OR  VERTEBRA, , 443 

1.  Cervical  Vertebrae, 446 

2.  Dorsal  Vertebra, 449 


CONTENTS. 

3.  Lumbar  Vertebra, 450 

4.  Pelvic  Vertebrae— Sacrum, 451 

Coccyx, 453 

5.  Ligaments  of  the  Spine 454 

SECTION  II. 
THORAX,  OR  CHEST, 460 

1.  Sternum, 460 

2.  Ribs, 463 

3.  Cartilages  of  Ribs, 465 

4.  Ligaments  of  the  Chest, 466 

5.  General  Remarks  upon  the  Chest, 468 

SECTION  III. 

PELVIS, 470 

Innominata, 470 

Ilium, 470 

Ischium, 472 

Pubis, 473 

Ligaments,.. 475 

Differences  between  Male  and  Female  Pelvis, 479 

CHAPTER  SECOND. 
ACTIVE  ORGANS  OF  THE  TRUNK, 481 

FIRST  DIVISION. 

ORGANS  BELONGING  TO  THE  NECK  AND  BACK, 481 

1.  The  Organs  of  Motion— Muscles, 481 

2.  Organs  of  Deglutition — CEsophagus, 481 

3.  Organs  of  Circulation— Blood-Vessels, 481 

4.  Organs  of  Innervation — The  Nerves, 481 

5.  Fascia  of  the  Neck, - 481 

6.  Lymphatic  Glands, 481 

7.  Thyroid  Gland, 481 

8.  Organ  of  Voice — Larynx, 481 

SECTION  I. 

ORGANS  OF  MOTION 481 

Muscles  of  the  Anterior  Neck, 481 

Dissection, 481 

Platisma  Myoides, 482 

Sterno  Clido  Mastoideus, 482 

Sterno  Hyoideus, 483 

Sterno  Thyroideus, 484 

Omo  Hyoideus, 484 

Triangles  of  the  Neck, 485 

Scalenus  Anticus, 486 

Scalenus  Medius, k 486 

Scalenus  Posticus, 486 


XX  CONTENTS. 

Longus  Colli f 487 

Rectus  Capitis  Anticus  Major, 487 

Rectus  Capitis  Anticus  Minor, 487 

Rectus  Capitis  Lateralis, 488 

SECTION  II. 

MUSCLEI    OF    THE   POSTERIOR    NECK   AND    BACK,.. 488 

Dissection, ' 488 

First  Layer, 488 

Trapezius, 488 

Latissimus  Dorsi, 489 

Second  Layer, 490 

Dissection, 490 

Rhomboideus  Minor, 490 

Rhomboideus  Major, 490 

Levator  Anguli  Scapulae, , 490 

Third  Layer, 491 

Dissection, 491 

Serratus  Posticus  Superior, 491 

Serratus  Posticus  Inferior, 492 

Splenius  Capitis  et  Colli, , 492 

Fourth  Layer, 492 

Dissection, 492 

Sacro  Lumbalis, 492 

Longissimus  Dorsi, 493 

Spinalis  Dorsi, 493 

Cervicalis  Ascendens, 493 

Transversalis  Colli, 494 

Trachelo  Mastoideus, 494 

Complexus, 494 

Fifth  Layer, 494 

Dissection, 494 

Rectus  Capitis  Posticus  Major, 494 

Rectus  Capitis  Posticus  Minor, 494 

Obliquus  Capitis  Superior, , 495 

Obliquus  Capitis  Inferior, 495 

Semi  Spinalis  Colli  et  Dorsi, 495 

Sixth  Layer, 496 

Dissection, 496 

Inter  Spinales, 496 

Inter  Transversales, 496 

Multifidus  Spinae, 496 

Levatores  Costarum 496 

Supra  Spinales, 496 

SECTION  III. 

ORGANS  OF  DEGLUTITION 497 

Oesophagus, 497 

Pneumogastric  Nerve,. 498 


CONTENTS.  XXI 


SECTION  IV. 

ORGANS  OF  CIRCULATION,  OR  THE  BLOOD-VESSELS  OF  THE  NECK 501 

Arteries — Common  Carotid, 501 

External  Carotid, 503 

Branches  of  External  Carotid, 503 

Superior  Thyroid, 503 

Facial, 504 

Occipital, 504 

Subclavian  Arteries,  at  the  Lower  Part  of  the  Neck, 504 

Branches  supplying  Neck — 

1.  Vertebral, 505 

2.  Thyroid  Axis, 506 

Inferior  Thyroid, 506 

Superior  Scapular, 506 

Posterior  Scapular, 507 

Cervicalis  Anterior, 507 

3.  Cervicalis  Posterior, or  Profunda  Cervicis,. 509 

Veins — The  Jugulars — 

External  Jugular ?V 507 

Internal  Jugular, 508 

Subclavian  Veins, 509 

SECTION  V. 

ORGANS  OF  INNERVATION,  OR  THE  NERVES  OF  THE  NECK, 509 

Par  Vagum, 509 

Spinal  Accessory, 509 

Lingual 510 

Facial 511 

Cervical  Plexus, 511 

Phrenic  Nerve, 512 

Brachial  Plexus, 513 

Sympathetic  and  its  Ganglia,... 514 

SECTION  VI. 

FASCIA  OF  THE  NECK, 522 

Lymphatic  Glands, 523 

Thyroid  Gland, 524 

SECTION  VII. 
ORGAN  OF  VOICE— The  Larynx, 525 

1.  Cartilages — 

Thyroid, 525 

Cricoid, 526 

Arytenoid, 526 

Epiglottis, 527 

2.  Ligaments, 527 

Muscles — Thyro  Hyoideus 529 

Crico  Thyroideus, 529 


XXH  CONTENTS. 

Thyro  Arytenoideus 530 

Crico  Arytenoideus  Posticus, 530 

Crico  Arytenoideus  Lateralis, 530 

Arytenoideus  Obliquus, 531 

Arytenoideus  Transversus, 531 

Thyro  Epiglottideus, 531 

Aryteno  Epiglottideus, 531 

Mucous  Membrane  of  Larynx  and  Glands 532 

Blood- Vessels  of  Larynx 533 

Relations  of  Larynx, 533 

Physical, 533 

Organic, 533 

Men  tal , 533 

Trachea, 534 

CHAPTER  THIRD. 

SECOND  DIVISION. 

ACTIVE  ORGANS  OP  TRUNK, 537 

ORGANS  OF  ABDOMEN, 537 

General  Observations, 537 

Boundaries  of  Abdomen, 537 

Regions  of  Abdomen, 537 

Organs  or  Viscera  in  each  region, 538 

Walls  of  Abdomen, 539 

SECTION  I. 

Dissection— Anterior  Walls— Obliquus  Externus, 539 

Obliquus  Internus, 542 

Transversalis, 543 

Rectus  Abdominis, 544 

Pyramidalis 545 

Posterior  Walls — Quadratus  Lumborum, 549 

Psoas  Muscles, 550 

Superior  Wall— Diaphragm, 551 

Inferior  Wall— Pelvis, 470 

SECTION  II.' 

ORGANS  OF  ABDOMINAL  DIGESTION, 554 

Organ  of  Chymification — The  Stomach 558 

Organs  of  Chylification— 1.  Membranous;  2.  Glandular- 
Membranous— Small  Intestine— Duodenum, 565 

Jejunum, 568 

Ilium, 568 

Organ  of  Faecation— Large  Intestine, 571 

1.  CoBcum, 572 

2.  Colon, 573 

3.  Rectum, 573 


CONTENTS.  XXIII 

Glandular  or  Assistant  Organs  of  Digestion, 576 

1.  Liver 576 

2.  Pancreas, 586 

3.  Spleen, 589 

SECTION  III. 
ORGANS  OF  ABSORPTION  OF  THE  TRUNK, 590 

CHAPTER  FOURTH. 

THIRD  DIVISION. 
ORGANS  OF  THE  CHEST, 596 

SECTION  I. 

MUSCLES  OF  THE  CHEST, 597 

Dissection, 597 

Pectoralis  Major, 597 

Pectoralis  Minor, 598 

Serratus  Major  Anticus, 598 

Intercostales,  External  and  Internal, 599 

Subclavius, 600 

Triangularis  Sterni, 600 

Pleura, 602 

SECTION  II. 

ORGANS  OF  RESPIRATION, 605 

Larynx, 605 

Trachea, 605 

Bronchi, 609 

Lungs, 605 

Thy mus  Gland, 613 

ORGANS  OF  CIRCULATION, 614 

Heart  and  Pericardium, 614 

Aorta  and  Branches, 626 

Vena  Cava,  Superior  and  Inferior, 627 

Vena  Azygos, 628 

Nerves  of  Thorax  and  Abdomen, 629 

CHAPTER  FIFTH. 

FOURTH  DIVISION. 

ACTIVE  ORGANS  OF  TRUNK, 637 

ORGANS  OF  URINATION, 637 

SECTION  I. 
KIDNETS, 637 

SECTION  II. 
URETERS, 643 

SECTION  III. 
BLADDER 643 


XXIV  CONTENTS. 


CHAPTER  SIXTH. 

FIFTH  DIVISION. 
ORGANS  OF  THE  PELVIS,  INCLUDING — 

1.  Male  Organs  of  Generation, 649 

2.  Female  Organs  of  Generation, 661 

SECTION  I. 
MALE  ORGANS — 

Testes, 649 

Vesiculoe  Seminales, 655 

Prostate  Gland, 655 

Penis, 656 

SECTION  II. 

FEMALE  ORGANS, 66 1 

External  Organs  of  Generation 661 

Vagina, 664 

Uterus, .-. 665 

Ovaries, 669 

SECTION  III. 

MUSCLES  OF  THE  PELVIS, 672 

Gluteii, 672 

Maximus, 672 

Medius, 673 

Minimus, 673 

Rotators — Pyriformis 674 

Gemini,  Superior  and  Inferior, 674 

Obturator  Internus, 674 

Obturator  Externus, 674 

Quadrator  Femoris, 675 

SECTION  IV. 
FASCIA  OP  PELVIS, 675 

SECTION  V. 

PERINEUM  OF  THE  MALE, 676 

Dissection, 676 

Muscles— Sphincter  Externus, 678 

Sphincter  Internus, 678 

Erector  Penis, 678 

Accelerator  Urinse, 679 

Transversus  Perinei, 679 

Coccygeus 679 

Levator  Ani, 679 

Blood-Vessels  and  Nerves, 680 

SUMMARY  OF  BLOOD-VESSELS  AND  NERVES  OF  TRUNK, 681 

SECTION  VI. 
ANATOMICAL  AND  PHYSIOLOGICAL  RELATIONS  OF  THE  MOUTH  WITH  THE 

DIFFERENT  ORGANS  OF  THE  TRUNK,  .  „ 684 


CONTENTS.  XXV 


PART  FOURTH. 
THE   EXTREMITIES. 

1.  SUPERIOR  EXTREMITY, 690 

2.  INFERIOR  EXTREMITY, * 742 

SUPERIOR   EXTREMITY. 

CHAPTER  FIRST. 

THE  PASSIVE  ORGANS — 

THE  BONES— 1.  Bones  of  the  Shoulder, 689 

2.  Arm, 692 

3.  Forearm, 694 

4.  Hand,.. 697 

SECTION  I. 

SHOULDER — 1.  Scapula, 689 

2.  Clavicle, 691 

SECTION  II. 
HUMERUS  OR  ARM  BONE, • 692 

SECTION  III. 
FOREARM,.. 694 

1.  Radius, 694 

2.  Ulna, 696 

SECTION  IV. 
HAND, 697 

1.  Carpus, 697 

2.  Metacarpus 699 

3.  Phalanges, 701 

SECTION  V. 
LIGAMENTS  OF  THE  SUPERIOR  EXTREMITY — 

Sterno  Clavicular  Articulation, 702 

Costo  Clavicular  Articulation, 703 

Scapulo  Clavicular  Articulation, 703 

Ligaments  of  the  Scapula, 703 

Arm, 704 

Forearm, » . . .  705 

Hand, 706 

Carpus, 706 

Metacarpus, 708 

Phalanges, 709 

2B 


XXVI  CONTENTS. 

CHAPTER  SECOND. 
ACTIVE  ORGANS  OF  THE  SUPERIOR  EXTREMITY, 709 

SECTION  I. 

MUSCLES  OF  THE  SUPERIOR  EXTREMITY, 709 

Of  the  Shoulder, 709 

Deltoid, 710 

Supra  Spinatus 710 

Infra  Spinatus, 710 

Teres  Minor, 711 

Teres  Major, 711 

Sub  Scapularis, 711 

Of  the  Arm, 712 

Biceps  Fiexor  Cubiti, 712 

Coraco  Brachialis 713 

Brachialis  Anticus, 713 

Triceps  Extensor  Cubiti, 713 

Anconeus, 714 

Of  the  Forearm, 714 

Pronator  Radii  Teres, 715 

Flexor  Carpi  Radialis, 715 

Palmaris  Longus, 715 

Flexor  Carpi  Ulnaris, 716 

Flexor  Digitorum  Sublimis  Perforatus, 716 

Flexor  Digitorum  Profundus  Perforans, 716 

Flexor  Longus  Pollicis, 717 

Pronator  Quadratus, 717 

Supinator  Radii  Longus, 717 

Extensor  Carpi  Radialis  Longior, 718 

Extensor  Carpi  Radialis  Brevior, 718 

Extensor  Digitorum  Communis, 719 

Extensor  Carpi  Ulnaris, 719 

Supinator  Radii*  Brevis, 719 

Extensor  Ossis  Metacarpi  Pollicis, 720 

Extensor  Major  Pollicis, 720 

Extensor  Minor  Pollicis, 720 

Indicator, 720 

Of  the  Hand, 722 

Abductor  Pollicis, 722 

Opponens  Pollicis, 722 

Flexor  Brevis  Pollicis, 722 

'     Adductor  Pollicis, 723 

Abductor  Indicis, 723 

Adductor  Minimi  Digiti, i 723 

Abductor  Minimi  Digiti, 723 

Flexor  Brevis  Minimi  Digiti, 723 

Palmaris  Brevis, 723 

Interosseous  Muscles, 724 


CONTENTS.  XXVH 


SECTION  II. 
FASCIA  OF  THE  SUPERIOR  EXTREMITY, 724 

SECTION  111. 

BLOOD-VESSELS  OF  THE  SUPERIOR  EXTREMITY, •• 726 

Arteries  of  the  Shoulder,. , 727 

Axillary  Artery, 727 

Branches — Thoracica  Acroraialis, 728 

Inferior  Thoracic, 728 

Thoracica  Axillaris, 728 

Subscapular  Artery, 728 

Anterior  Circumflex, 728 

Posterior  Circumflex, 729 

Arteries  of  the  Arm, 729 

Brachial  Artery, 729 

Profunda  Superior, 729 

Profunda  Inferior, 730 

Anastomotica  Magna, 730 

Muscular  Branches, 730 

Arteries  of  the  Forearm, 731 

Radial  Artery, 731 

Branches — Recurrens  Radialis, 731 

Muscular  Branches, 731 

Superficial  Volas, 731 

Dorsalis  Carpi, 731 

Radialis  Indicis, 731 

Magna  Pollicis, 731 

Ulnar  Artery 732 

Branches — Recurrens  Ulnaris, 732 

Interosseous  Artery, 733 

Anterior  Interosseal  Artery, 733 

Posterior  Interosseal  Artery, „ . . .  733 

Dorsalis  Carpi  Ulnaris, 733 

Arteries  of  the  Hand, 733 

Arcus  Superficial, 733 

Digital  Arteries, 733 

Arcus  Profundus 734 

Veins  of  the  Superior  Extremity — Cephalic  Vein, 735 

Basilic, 735 

Median  Vein, 736 

Axillary  Vein,. . 736 

NERVES  OF  THE  SUPERIOR  EXTREMITY, 736 

Axillary  Plexus, 736 

Branches— Thoracic  Nerves, 737 

Supra  Scapular, 737 

Sub  Scapular, 737 

Internal  Cutaneous, 738 

External  Cutaneous, 739 

Circumflex. .  739 


XXVm  CONTENTS. 

Median, 739 

Ulnar 740 

Radial  Nerves, 740 

Intercosto-humeral  Nerves, 741 

SUMMARY  OF  THE  MUSCLES  OF  THE  SUPERIOR  EXTREMITIES, 741 

INFERIOR    EXTREMITY. 

CHAPTER  FIRST. 
BONES  AND  LIGAMENTS, 742 

SECTION  I. 

BONE  OF  THE  THIGH, «... 742 

Os  Femoris, 742 

SECTION  II. 

BONES  OF  THE  LEG, 745 

Tibia, 745 

Fibula, 746 

Patella, 747 

SECTION  III. 

BONES  OF  THE  FOOT, 748 

Tarsus, 748 

Metatarsus, 750 

Phalanges, 751 

SECTION  IV. 

LIGAMENTS  OF  THE  INFERIOR  EXTREMITIES, 751 

Ligaments  of  the  Hip  Joint, 751 

Ligaments  of  the  Knee  Joint, 752 

Ligaments  of  the  Ankle  Joint, 755 

Ligaments  of  the  Foot, 756 

CHAPTER  SECOND. 
ACTIVE  ORGANS  OF  THE  INFERIOR  EXTREMITIES, 757 

SECTION  I. 

MUSCLES  OF  THE  INFERIOR  EXTREMITIES, 757 

Muscles  of  the  Thigh, 757 

Anterior  and  Inner  Thigh — 

Sartorius, 758 

M  ;.- 1    Rectus  Femoris, 758 

Vastus  Externus, 759 

Vastus  Internus 759 

Cruraeus, 759 

G racilis, 759 

Pectineus 760 

Adductor  Longus, 760 


CONTENTS.  XXIX 

Adductor  Brevis, 760 

Adductor  Magnus, 760 

Outer  Thigh— Tensor  Vaginae  Femoris, < 758 

Posterior  Thigh — Biceps  Flexor  Cruris, 761 

Semitendinosus, •  761 

Semimembranosus , 671 

Muscles  of  the  Leg, 762 

Anterior  and  Outer  Leg — 

Tibialis  Anticus, 762 

Extensor  Communis  Digitorum  Pedis, 762 

Extensor  Proprius  Pollicis, 763 

Peroneus  Longus, 763 

Peroneous  Brevis, 763 

Peroneus  Tertius 764 

Posterior  Leg — Gastrocnemius 764 

Plantaris, 765 

Popliteus, 765 

Flexor  Communis  Digitorum  Pedis, 765 

Flexor  Longus  Pollicis, 766 

Tibialis  Posticus, 766 

Muscles  of  the  Foot, 766 

First  Layer— Abductor  Pollicis  Pedis, 766 

Abductor  Minimi  Digiti 767 

Flexor  Brevis  Digitorum, 767 

Second  Layer — Flexor  Accessorius, 767 

Lumbricales  Pedis, 767 

Third  Layer— Flexor  Brevis  Pollicis, 768 

Adductor  Pollicis, 768 

Flexor  Brevis  Minimi  Digiti, 768 

Transversalis  Pedis, 768 

Fourth  Layer— Interosseii  Plantares, 769 

Dorsum  of  Foot— Interosseii  Dorsales, •  •  •  • 769 

Extensor  Brevis  Digitorum  Pedis, 766 

SECTION  II. 

FASCIA  OF  THE  INFERIOR  EXTREMITY, 769 

Superficial  Fascia, 769 

Fascia  Lata, 769 

SECTION  III. 

BLOOD-VESSELS  OF  THE  INFERIOR  EXTREMITIES, 772 

Arteries.— Femoral  Artery, 772 

Branches— Superficial  Epigastric, 773 

Superficial  Circumflexa  Ilii, 773 

External  Pudic 773 

Profunda  Femoris, 773 

External  Circumflex, 773 

Internal  Circumflex, ; . . .  774 

Perforating  Arteries, 774 

Anastomotica  Magna, 774 


XXX  CONTENTS. 

Popliteal  Artery, 774 

Branches— Muscular  Branches, 775 

Superior  Articular, 775 

External, 775 

Internal, 775 

Inferior  Articular, 775 

External, 775 

Internal 775 

Middle  Articular, 775 

Gastrocnemial  Branches, 775 

Anterior  Tibial  Artery,- 775 

Branches — Recurrent  Tibial, 776 

Muscular  Branches 776 

Malleolar, 776 

Internal, 776 

External, 776 

Metatarsal, 776 

Arteria  Pollicis, 776 

Communicans, 776 

Posterior  Tibial  Artery, 776 

Branches — Peroneal  Artery, 776 

Muscular  Branches, 777 

Nutritious  Artery, 777 

Plantar  Arteries, 777 

Internal, 777 

External, 777 

Digital  Arteries, 777 

Veins  of  the  Inperior  extremity, 778 

Saphena  Vein — Internal, 778 

External 778 

Tibial  Veins— Anterior, 778 

Posterior, 778 

Peroneal  Veins, 778 

Popliteal  Vein, 778 

Femoral  Vein 778 

SECTION  IV. 

NERVES  OF  THE  INFERIOR  EXTREMITY, 779 

Anterior  Crural  Nerve— Muscular  Branches, 779 

Internal  Saphenus, 779 

Sacral  Plexus — Branches— Lesser  Sciatic  Nerve, 780 

Cutaneous  Branches 780 

Gluteal, 781 

Great  Sciatic, 781 

Popliteal  Nerve, 781 

Posterior  Tibial, 782 

Peroneal 783 

SUMMARY  OF  THE  MUSCLES  OF  THE  INFERIOR   EXTREMITIES, 784 

ANATOMICAL  AND  PHYSIOLOGICAL   RELATIONS  OF  THE  MOUTH  WITH  THE 

EXTREMITIES, 785 


LIST    OF    ILLUSTKATIONS. 


no.  PAGE 

1  Nucleated  cell,  ......................    63 

2  Blood  corpuscle,  .....................     71 

8  Cellular  tissue,  ......................    76 

4  Adipose  tissue,  ......................    79 

5  Capillary  tissue,  ......................    84 

6  Portal  circulation,  ....................    87 

7  General  circulation,  ..................    89 

8  Distribution  of  the  arteries,  ...........    95 

9  Venous  circulation,  ..................  100 

10  Heart,  ...............................  102 

11  Double  heart,  ........................  103 

12  Foetal  circulation,  ....................  105 

3  Minute  structure  of  nerve,  ............  108 

14  Spinal  marrow,  ......................  112 

15  Spinal  marrow,  section  of,  ...........  113 

16  Brain,  ...............................  114 

17  Mammary  gland,  ....................  118 

18  Thoracic  duct,  .......................  121 

19  Skin,  structure  of,  ....................  125 

20  Epithelium  scales,  ...................  135 

21  Columnar  epithelium,  ................  136 

22  Ciliated  epithelium,  ..................  136 

23  Gastric  pits,  .....  .7  ..................  138 

24  Brunner's  glands  ....................  138 

25  Peyer's  glands,  ......................  138 

26  Muscular  fibre  of  animal  and  organic 

life,  ..............................  144 

27  Attachment  of  tendon  to  muscular  fibre,  147 
23  White  and  yellow  fibrous  tissue,  ......  149 

29  Cartilage  corpuscles,  ................  153 

30  Texture  of  bone,...?  .................  16? 

oo  Concentric  Lamella}  of  bone,  .........  168 

62,  Haversian  canals,  ....................  169 

Frontal  bone,  front  view,  .............  ITS 

»4  S  rontal  bone,  inner  view,  ............  178 

b5  J  rontal  bone,  lower  portion,  ..........  179 

)  1  arietal  bone,  outer  surface,  ..........  ISO 

.  1  arietal  bone,  inner  surface,  ..........  181 

W  Occipital  bone,  outer  surface,  .........  182 

Occipital  bone,  inner  surface,  .........  183 

10  iemporal  bone,  outer  surface,  ........  185 

L  Iemporal  bone,  inner  surface,  ........  186 

Jkthmoid  bone,  .......................  189 

43  Sphenoid  bone,  ...............  *  191 


Malar  bones,'.  .....  V.  .V.V.  .V.V.V.V  '.V.  2 

Lachrymal  bones,  (os  unguis,)  .......  206 

Nasal  bones,  ...........  ........  207 

Inferior  turbinated  bones,  .......  '.'.'.'.".  208 

v  omer,  .......................  208 

Inferior  maxillary  bone,."..".'.'."  "  209 

ArHCaiat|on  of  lower  juw,  .....  21o 

Sutures  of  the  cranium,..'  ....... 

Base  of  the  cranium'. 

Muscles  of  the  face,  .'......          .......  |l| 

Articu'ation  of  the  teeth,  ...... 

Incisor  teeth,  .......... 

Cuspidali......  ..............  5 

Bi-cuspidati,  ......  '.  ............  90 

Molars,....  '.........  .................  |fj 

Structure  and  pulp  cavities  of  teeth,'.!'.  285 
Blood-vessels  of  pulp,.  .  .  .  oo,5 

Nerves  of  pulp,  .  ..  .  J  )  .....  / 

Cellular  arrangement  of  the  pulp  "  !. 
Baccated  view  :  of  the  dentine,....  .....  237 

Blood.-vessels  of  dentine,  ......  .     240 

Dentine  according  to  Mr.  Tomes,  .....  242 


FIG. 

68  Enamel  fibres,  ...................... 

69  Temporary  teeth,  ................... 

70  The  two  sets  of  teeth,  ................ 

71  Origin  and  progress  of  the  teeth,  ..... 

72  Different  structures  of  a  toolh,  ........ 

73  Arteries  of  the  face,  ................. 

74  Fifth  pair  of  nerves,  ................. 

75  Dental  arch  of  Chimpanzee,  ......... 

76  Deciduous  and  permanent  teeth  of  the 

dog,  ............................. 

77  Deciduous  and  permanent  teeth  of  the 

bear,  ............................. 

78  Deciduous  and  permanent  teeth  of  the 

hog,  ..........  •  ................... 

79  Section  of  the  incisor  of  a  horse,  ...... 

80  Poison  fangs  of  serpents,  ............ 

81  Teeth  of  the  rock  fish,  ............... 

82  Muscles  of  the  face,  ................ 

83  Temporal  muscle,  ................... 

84  Pterygoid  muscles,  .................. 

85  Salivary  glands,  ..................... 

86  Muscles  of  the  lower  jaw,  ............ 

87  A  side  view  of  the  tongue,  ........... 

88  Muscles  of  the  soft  palate,  ........... 

89  The  tongue,  ........................ 

90  Papillae  of  the  tongue,  ............... 

91  Nerves  of  the  tongue,  ............... 

92  The  pharynx,  ..................... 

93  Cavity  of  the  mouth,  ................ 

94  Glands  of  the  lips,  .................. 

95  Vascularity  of  the  lips,  ............. 

96  Papilla?  of  the  gums,  ................ 

97  Facial  nerve,  .......  ................ 

98  The  eye......  ..................  .... 

99  The  eye—  transverse  section,  ........ 

100  The  retina,  ................  .  ........ 

101  Nerves  of  the  eyeball,  ............... 

102  Muscles  of  the  eyeball,  ............... 

103  Meibomian  glands,  .................. 

104  Lachrymal  apparatus,  ............... 

105  The  external  ear,  ................... 

106  External,  middle,  and  internal  ear,.  .  . 

107  Little  bones  of  the  ear,  .............. 

108  Labyrinth  of  the  ear,  ................ 

1  09  Labyrinth  of  the  ear,  ,  ............... 

110  Olfactory  nerves,  ................... 

111  Nasal  Fossae,  ....................... 

1  12  Sinuses  of  the  dura  mater,  ........... 

113  Cerebellum,  ....................... 

114  Arbor  vibe,  ......................... 

115  Convolutions  of  cerebrum,  ........... 

116  Longitudinal  section  of  the  brain,  ____ 

117  Horizontal  section  of  the  brain,  ....... 

118  Optic  nerves  ........................ 

119  Circle  of  Willis,  ..................... 

120  Branches  of  external  carotid,  ........ 

121  Internal  maxillary  artery,  ........... 

122  Spinal  column,  .  ..  .....  ...  ...... 

123  A  lumbar  vertebra,  ................  . 

124  Cervical  vertebne,  ....... 

125  The  atlas,  .......  !  ....... 

126  Thedentata,  ....................... 

1  27  Seventh  cervical  vertebrae  ........ 

128  A  dorsal  vertebra,  .......  .    ......... 

129  A  lumbar  vertebra,  ................. 

180  Sacrum,  ....... 

131  Coccyx,  .................  '.".'.".".V.V..".'.' 

132  Anterior  vertebral  ligament,  ......... 


243 
244 
245 
249 
254 
260 
263 
274 

280 
281 

235 

28T 
091 

292 
294 
295 
ong 

299 

304 

305 

QAT 

310 

312 

014 

£} 

313 

3^9 

320 

321 


339 
345 
349 
357 
353 
361 


371 
875 
380 
882 
39T 
404 
405 
409 
413 
415 
401 
4|g 
423 
400 

! 

443 
443 
450 
451 
2w 
454 
455 


XXXH 


LIST  OP  ILLUSTRATIONS. 


183  Posterior  vertebral  ligament, •  455 

134  Yellow  ligaments, 456 

185  Ligaments  of  atlas  and  dentata, 458 

136  Ligaments  of  atlas  and  dentata, 459 

137  Sternum  and  ribs, 461 

138  Ribs, 463 

139  First  rib, 464 

140  Ligaments  of  the  ribs, 467 

141  Ligaments  of  sternum  and  ribs, 467 

142  Os  innominatum, 470 

148  Ligaments  of  the  pelvis, 476 

144  Ligaments  of  the  pelvis, 477 

145  Diameters  of  the  pelvis, 480 

146  Superficial  muscles  of  the  neck, 481 

147  Muscles  of  the  neck, 483 

148  Deep  muscles  of  the  neck, 486 

149  Muscles  of  the  neck  and  back, 489 

150  Muscles  of  the  back, 491 

151  Muscles  ot  the  back, 493 

152  The  eighth  pair  of  nerves, 498 

153  Blood-vessels  and  nerves  of  anterior 

neck,..." 502 

154  Veins  of  the  neck 508 

155  Sympathetic  nerve, 515 

156  Cranial  ganglia, 517 

157  Orig  n  of  sympathetic  nerve, 519 

158  Thyroid  cartilage, 525 

159  Cricoid  Cartilage, 526 

160  Arytenoid  cartilages, 526 

161  Epiglottis, 527 

162  Muse  es  of  the  larynx, 529 

163  Muscles  of  the  larynx, 530 

164  Muscles  of  the  larynx, 530 

165  The  trachea, 535 

166  Eegions  of  the  abdomen, 538 

167  Muscles  of  the  abdomen, 540 

168  Inguinal  Hernia, 541 

169  Transversalis  muscle, 544 

170  Internal  abdominal  ring, 547 

171  Blood- vessels  of  ant'r  abdominal  wall,  548 

172  Muscles  of  posterior  abdominal  wall, .  549 
178  The  diaphragm, 552 

174  Reflections  of  the  peritoneum, 555 

175  Stomach  and  intestines, 559 

176  Coats  of  the  stomach, 560 

177  Interior  of  the  stomach, 561 

178  Gastric  favuli, S62 

179  Gastric  glands, 562 

180  Arteries  of  stomach, 564 

181  Duodenum, 565 

182  Lacteal  tube, 567 

183  Glands  of  Brunner, 568 

184  Ilium,  colon  and  mesentery, 569 

185  Large  intestine, 571 

186  Anus,  section  of, .     575 

187  The  liver, 576 

188  Venaporta, 580 

189  Lobules  of  the  liver, 583 

190  Lobules  of  the  liver, 684 

191  The  pancreas, 586 

192  The  spleen, 589 

193  Serratus  major  anticus, 599 

194  Lactiferous  ducts, 602 

195  The  pleura, ..  603 

196  The  lungs, 606 

197  The  lungs  and  heart, 608 

198  Cavities  of  the  heart;. 616 


199  Right  heart, 617 

200  Left  ventricle, 621 

201  Muscular  fibres  of  the  heart, 622 

202  Connection  of  sympathetic  with  spinal 

nerve, 680 

203  Plexuses  of  sympathetic  nerves, 632 

204  Lumbar  and  ischiatic  plexuses, 634 

205  Urinary  apparatus, 638 

206  Section  of  kidney, 639 

207  Urinary  bladder, 644 

208  Testicle,  transverse  section  of, 650 

209  Testicle,  structure  of, 652 

210  Penis  and  bladder, 65T 

211  Female  organs  of  generation, 664 

212  Muscles  of  the  pelvis, 672 

213  Male  perineum, 677 

214  Blood-vessels  of  the  trunk, 688 

215  The  scapula, 690 

216  The  clavicle, 691 

217  The  humerus, 693 

218  Radius,  ulna, 695 

219  The  carpus, 698 

220  Metacarpus,  phalanges, 700 

221  Ligaments  of  shoulder  joint, 704 

222  Elbowjoint, 706 

223  Wrist  joint, 707 

224  Muscles  of  the  shoulder, 711 

225  Muscles  of  the  arm, 712 

226  Triceps  muscle, 714 

227  Muscles  of  the  forearm, 715 

228  Muscles  of  the  forearm, 71T 

229  Muscles  of  the  forearm, 718 

230  Muscles  of  the  forearm, 720 

231  Extensor  accessorius  indicis, 721 

232  Muscles  of  the  hand, 722 

233  Axillary  artery  and  nerves, 727 

234  Brachial  artery  and  nerves, 730 

235  Radial  and  ulnar  arteries, 732 

236  Arteries  of  the  hand, 734 

287  Veins  of  superior  extremity, 735 

288  Nerves  of  superior  extremity, 737 

239  Cutaneous  nerves  of  elbow  joint, 738 

240  Os  Femoris, 743 

241  Tibia  and  Fibula, 745 

242  The  patella, 747 

243  Bones  of  the  foot, 748 

244  Ligaments  of  hip  joint, 752 

245  Ligaments  of  knee  joint, 753 

246  Ligaments  of  knee  joint, 754 

247  Ligaments  of  ankle  joint, 755 

248  Ligaments  of  foot, 756 

249  Muscles  of  thigh, 758 

250  Muscles  of  thigh, 761 

251  Muscles  of  leg, 762 

252  Muscles  of  leg, 764 

253  Muscles  of  leg, 765 

254  Muscles  of  foot, 767 

255  Muscles  of  foot, 768 

256  Muscles  of  foot, 769 

257  Femoral  artery, 773 

258  Popliteal  artery, 774 

259  Anterior  tibial  artery, 775 

260  Arteries  of  the  foot, 777 

261  Saphena  vein, 778 

262  A  nterior  crural  nerve, 780 

268  Sacral  plexus, 781 

264  Plantar  nerves, 783 


Errata. — A  few  typographical  errors  have  occurred  in  the  printing  of  the 
work,  which  the  attentive  reader  will  be  able  to  correct. 


INTRODUCTION , 


HISTORY  OF  ANATOMY. 

ALL  that  we  propose,  under  the  present  head,  is  simply 
to  give  a  very  brief  outline  of  the  Art  of  Dissection,  for 
the  purpose  of  showing,  by  way  of  contrast,  its  past  and 
present  state. 

The  Art  of  Dissection  appears  to  be  of  great  antiquity,  it 
being  the  custom  to  sacrifice  animals  to  the  Deity,  some 
parts  being  set  aside  for  the  sacrifice,  and  others  for  the  use 
of  the  priests.  It  hence  became  necessary  to  discriminate, 
or  distinguish  the  one  from  the  other.  This  kind  of  know- 
ledge, however,  belonged  to  Comparative  Anatomy,  and  at 
that  day  was  mostly  confined  to  the  butchers. 

It  is  supposed  that  the  cruel  custom  of  human  sacrifices 
originated  the  first  information  we  have  of  the  human  body; 
for  in  such  cases  it  was  necessary  that  some  knowledge  of 
the  internal  structure  of  the  human  frame  should  be  ac- 
quired by  the  priests,  that  they  might  properly  conduct 
such  ceremony. 

The  first  attempt  at  making  Anatomy  a  science,  is  ascribed 
to  Pythagoras,  and  Tholes  of  Miletum,  about  700  years  before 
Christ,  who,  we  are  told,  made  it  a  part  of  their  studies. 
Empedocles,  about  100  years  after  this,  showed  considerable 
Anatomical  knowledge,  especially  in  reference  to  the  coddea 
and  tube  of  the  ear. 

The  first  who  dissected  animals,  with  a  view  to  learning 
their  internal  structure,  was  Alcmeeon,  a  disciple  of  Py- 
3 


34  INTRODUCTION. 

thagoras.  But  it  is  to  Hippocrates,  who  is  styled  the  father 
of  medicine,  that  we  are  directed  to  look,  as  being  the  pos- 
sessor of  all  the  Anatomy  known  in  his  day,  which  was 
about  500  years  before  Christ.  This  knowledge,  if  such 
it  may  be  called,  though  it  abounded  in  errors,  and  in  a 
great  measure  necessarily  so,  from  the  dissections  being 
mostly  confined  to  inferior  animals,  and  from  the  supersti- 
tions of  the  age,  and  insuperable  obstacles  constantly  oppo- 
sing human  dissections :  we  say,  in  view  of  all  this,  we 
cannot  refrain  uniting  in  the  language  of  an  author,  "that 
the  perseverance  and  acquirements  of  this  great  man,  the 
ornament  of  the  medical  profession,  cannot  be  sufficiently 
admired."  A  few  specimens  of  his  Anatomical  knowledge 
will  here  suffice.  The  left  ventricle  of  the  heart  he  supposed 
the  seat  of  the  soul.  The  arteries  he  thought  conducted 
the  spirits.  The  liver  he  believed  to  be  the  fountain  of 
the  blood,  and  the  root  of  the  veins.  The  heart  and  lungs 
he  supposed  received  part  of  our  drink.  The  auricles  were 
believed  to  serve  the  purpose  of  a  fan;  and  no  distinction 
was  made  between  arteries,  veins,  nerves  and  tendons. 

After  Hippocrates,  the  study  of  Anatomy  seemed  to  be 
chiefly  confined  to  the  two  schools  of  Athens  and  Alexandria. 
To  the  former  belong  the  names  of  Socrates,  Plato,  Xeno- 
phon,  Aristotle  and  Theophrastus.  And  although  their 
attention  was  principally  directed  to  the  study  of  Philosophy, 
yet  a  knowledge  of  Anatomy  was  not  overlooked,  though 
the  examination  of  bodies  was  very  much  restricted. 

In  the  Alexandrian  school,  however,  Anatomy  greatly 
flourished.  It  received  the  protection,  favor,  and  presence 
of  the  Ptolemies.  Anatomy  was  here  publicly  taught. 
Dissections  of  human  bodies  were  made,  and  we  are  in- 
formed that  kings  were  sometimes  present  at  them.  Hero- 
philus  and  Erasistratus  were  the  distinguished  masters  of 
Anatomy  in  this  school.  We  are  told  that  they  dissected 
several  hundred  bodies,  and  were  especially  famous  for 
their  productions  in  Neurology. 

From  Herophilus  and  Erasistratus,  to  Galen,  embracing  a 


INTRODUCTION.  35 

period  of  500  years,  trie  names  of  Asdepiades,  Eufus  Ephese- 
uSj  and  Celsus,  stand  most  prominent.  The  two  latter  gave 
the  names  and  localities  to  many  parts  of  the  body.  Clau- 
dius Galenus  or  Galen  appeared  and  flourished  about  the 
close  of  the  second  century.  He  was  considered  one  of  the 
most  remarkable  and  learned  men  that  ever  lived.  He 
applied  himself  especially  to  the  investigation  of  Anatomy, 
but,  unfortunately,  his  descriptions  were  mostly  taken  from 
the  brute  creation.  In  his  works,  Anatomy  is  made  to 
occupy  a  prominent  and  methodical  place,  and  for  1500 
years  his  name  and  influence  reigned  supreme,  in  spite  of 
all  his  errors;  so  much  so,  that  it  was  considered  the  very 
height  of  medical  folly  even  to  suspect,  and  a  far  more 
unpardonable  presumption  to  call  in  question  and  attempt 
to  correct  any  of  his  opinions. 

A  treatise  "on  the  nature  of  man,"  is  recorded  as  being 
the  production  of  Nemesius,  Bishop  of  Emissa,  who  wrote 
about  the  end  of  the  fourth  century,  his  most  prominent 
Anatomical  claim  being  the  discovery  of  the  use  of  the  bile. 
From  the  period  of  Galen  to  the  16th  century,  Anatomy, 
with  every  other  kind  of  learning,  was  on  the  decline.  Du- 
ring this  long  lapse  of  what  has  been  very  significantly 
styled  the  Dark  Ages,  very  little  or  no  improvement  was 
made.  After  the  destruction  of  Alexandria,  learning,  as 
much  as  was  left,  was  introduced  among  the  Arabians,  and 
they  applied  themselves  to  the  study  of  "physic;"  but,  as 
their  law,  like  that  of  the  Jew,  prohibited  dissections,  of 
course  they  could  make  but  little  improvement. 

In  the  llth  century,  the  school  of  Salernum,  in  Sicily, 
was  established,  and  obtained  considerable  reputation.  But 
owing  to  the  ignorance  and  superstition  of  the  times,  and 
from  its  being  viewed  as  a  "crime"  to  dissect  a  human  body, 
this  school  did  little  more  than  teach  the  dogmas  of  the 
Arabian  doctors. 

About  the  close  of  the  12th  century,  Abdollalliph  distin- 
guished himself  in  osteology,  by  exposing  many  of  the 
errors  of  Galen  in  this  department. 


36  INTRODUCTION. 

In  the  commencement  of  the  14th  century,  Mundinus  is 
represented  as  the  first  European  author  who  insisted  upon 
dissections,  and  whose  system  of  instruction  was  of  so  high 
repute,  as  to  be  taught  for  years  in  the  schools.  Even 
in  the  University  of  Padua,  the  Professors  were  obliged, 
by  a  law  of  the  College,  to  make  this  system  their  text- 
book. 

Towards  the  close  of  the  15th  century,  Jacobus  Beren- 
garius  Carpus  revived  dissections,  and  published  two  Ana- 
tomical works,  one  of  which  was  simply  a  commentary  on 
Mundinus. 

The  16th  century  teems  with  improvements  and  discov- 
eries in  anatomy,  from  men  of  the  most  exalted  talent, 
untiring  industry,  and  self-sacrificing  devotion  to  this,  their 
favorite  pursuit.  Italy  for  a  long  time  seemed  ttf  be  the 
sole  theatre  of  Anatomical  knowledge.  About  the  year 
1536,  however,  John  Gruinterius,  who  had  been  a  teacher 
of  Anatomy  for  several  years  in  Paris,  published  a  work 
entitled  "Anatomicse  Institutiones,"  in  which,  it  is  said,  he 
has  given  a  pretty  full  and  accurate  description  of  the 
muscles. 

But  it  is  most  especially  to  that  great  man,  Andreas  Vesa- 
UuSj  of  Brussels,  that  we  are  to  look  for  the  restoration  of 
Anatomy.  He  was  the  real  and  true  reformer,  the  bold 
and  unflinching  Luther  in  practical  Anatomy,  the  untiring 
zealot  in  dissections,  and  the  prompt  and  fearless  exposer 
of  error.  Hence,  he  very  soon  brought  himself  into  trouble, 
by  daring  to  expose  the  numerous  errors  of  Galen  and 
others,  of  the  existence  of  which  his  dissections  at  every  step 
clearly  convinced  him.  He  published  his  Anatomy  in  1543, 
and  his  descriptions  of  the  bones  and  muscles  are  stated  to 
be  very  minute,  and  not  much  surpassed  even  by  modern  au- 
thors. His  figures  are  described  as  master-pieces  of  paint- 
ing. Vesalius  attended  Lectures  in  Paris,  to  which  he  had 
been  invited  by  the  Professors  of  the  University.  He  devo- 
ted himself  to  dissections,  by  clandestinely  procuring  bodies 
for  that  purpose,  and  in  the  proportion  that  he  discovered 


INTRODUCTION.  37 

Galen's  errors  in  Anatomy,  in  the  same  proportion  did  his 
veneration  for  that  great  man  diminish,  and  this  he  did 
not  fail  openly  to  avow  and  publish.  Immediately  he  had 
a  host  of  enemies  to  encounter,  and  so  hot  was  the  opposi- 
tion, that  he  was  obliged  to  leave  Paris.  His  criticisms  on 
Galen  were  published  when  he  was  only  28  years  of  age, 
in  consequence  of  which  daring  and  impious  opposition,  as 
it  was  supposed,  to  the  infallible  Galen,  all  Europe  seemed 
in  arms  against  Yesalius.  And  what  was  most  trying,  his 
Preceptor,  Sylvius ,  at  Paris,  was  the  most  bitter  among 
his  opponents.  Sylvius  changed  the  name  of  Yesalius  to 
that  of  Vesanu§  or  madman.  In  defiance  of  all  opposition, 
however,  his  reputation  increased,  and  he  was  appointed 
Professor  of  Anatomy  in  the  University  of  Padua,  by  the 
Eepublic  of  Venice,  which  chair  he  filled  for  seven  years. 
He  was  also  first  Physician  to  the  Emperor,  Charles  Y,  who 
kept  him  constantly  at  court. 

Vesalius'  work,  "De  structura  corporis  Humani"  is  said  to 
have  been  published  when  he  was  but  about  25  years  of  age. 
In  1561,,  Gabriel  Fallopius,  a  pupil  of  Vesalius,  distinguished 
himself.  He  was  Professor  of  Anatomy  in  the  University 
of  Padua,  and  also  author  of  an  anatomical  treatise  under 
the  title  of  " Observations  Anatomicce" 

It  was  intended  more  as  a  supplement  to  the  work  of 
Vesalius,  many  of  whose  descriptions  he  corrects,  which 
Vesalius  it  seems  did  not  much  like,  and  in  consequence 
replied  to  his  pupil. 

In  1563,  Bartliolomcms  Eustachius  published  at  Venice  a 
work  called  " Opuscula  Anatomicce"  which  is  highly  spoken 
of.  He  is  distinguished  for  his  Anatomical  pursuits  and 
discoveries. 

The  Ifah  century  opens  with  the  brilliant  discovery  of  the 
circulation  of  the  blood,  by  Dr.  Wm.  Harvey,  in  1628. 

The  previous  discoveries  of  Fabricius  on  the  valves  in  the 
veins — and  those  of  Servitus,  Columbus  and  Caesalpinus,  on 
the  circulation  through  the  lungs,  were  very  important  links 
to  Harvey  in  making  his  immortal  discovery.  He  met  with 


38  INTRODUCTION. 

much,  opposition  at  the  time,  hut  lived  to  see  his  doctrine 
universally  embraced.  In  1642,  Wirtsungius  discovered  the 
pancreatic  duct.  Aselius,  an  Italian,  discovered  the  lacteals, 
which  Pecquet  in  1651  traced  to  the  thoracic  duct,  and  on  to 
the  suhclavian  vein.  In  this  same  year  Thos.  Bartholine 
has  the  credit  of  discovering  the  lymphatic  vessels — though 
a  Swede  by  the  name  of  Olaus  Rudbeck,  and  Jolivius  an  Eng- 
lishman, both  put  in  their  claims  for  priority  of  discovery. 

In  1660,  Marcellus  MalpJiigius  became  eminent  for  the 
accuracy  of  his  descriptions,  and  for  his  discoveries  of  new 
structures. 

About  this  period,  Johannes  Swammerdam  made  some 
Anatomical  publications,  and  was  particularly  celebrated 
for  his  manner  of  preserving  different  portions  of  bodies  by 
injecting  their  vessels. 

In  1665,  Frederic  Ruysch,  the  great  Dutch  Anatomist, 
made  his  first  Anatomical  publication,  which  he  continued 
for  a  period  of  65  years,  being  universally  celebrated  for  his 
minute  injections,  and  for  preserving  every  part  of  the  body 
in  its  natural  color,  and  with  all  its  original  freshness  and 
beauty. 

In  1683,  Gothofridus  Bidloiv,  Professor  of.  Anatomy  at 
Leyden,  published  his  "AnatomiacorporisHumani"  where- 
in it  is  said  the  several  parts  are  represented  in  plates  as 
large  as  life.  The  plates  are  supposed  to  be  those  of  Swam- 
merdam, which  had  never  before  been  made  public. 

Shortly  after  this,  Diembroeck,  Professor  of  Anatomy  at 
Utrecht,  prepared  a  work  which  became  the  standard  work 
among  students. 

Antonius  Leuwenhoeck  about  this  time  also  distinguished 
himself  by  the  use  of  the  microscope. 

The  names  of  Albinus,  Winslow,  and  Cheselden,  with 
many  others,  are  all  famous  in  this  century  for  their  ana- 
tomical knowledge. 

The  18th  century  presents  the  brilliant  names  of  Bichatj 
the  father  of  General  Anatomy,  Morgagni,  Scarpa,  Soemmer- 
mg,  the  Monros,  the  Hunters,  and  a  host  of  others. 


INTRODUCTION.  39 

The  19th  century  is  no  less  remarkable  for  its  onward 
march  and  progressive  improvement  in  Anatomy.  Every 
nation  seems  to  be  vying  with  every  other  in  that  most 
honorable  and  useful  of  all  species  of  rivalries,  a  more  com- 
plete— yea,  the  most  perfect  knowledge  of  the  structure  of 
the  body  possible — with  the  view  of  more  fully  preserving 
health  and  prolonging  life ;  and  the  kind  of  Anatomical  dis- 
covery and  improvement  which  characterizes  the  present 
period,  may  be  designated  by  the  term  Microscopic  Anatomy. 
In  this  department  figure  the  names  of  Schwann,  Muller, 
Andral,  Magendie,  Carpenter,  Nasmyth,  Goodsir — and  in 
our  own  country,  the  names  of  Wistar,  Godman,  Homer  and 
Leidy,  may  be  mentioned — the  two  former  being  more  par- 
ticularly distinguished  for  their  observations  in  the  ordi- 
nary mode  of  dissections,  while  the  latter  have  directed 
special  attention  to  microscopic  Anatomy.  Numerous  oth- 
ers equally  eminent  and  indefatigable  in  our  own  and 
every  other  country,  might  be  mentioned,  who  are  now  un- 
ceasingly engaged  both  in  microscopic,  and  all  other  species 
of  Anatomical  analysis  and  research,  which  can  by  any  pos- 
sibility shed  a  more  perfect  light  and  thorough  knowledge 
upon  the  wonderful  minuteness,  complexity,  and  harmony 
in  the  structure  of  the  human  frame. 

Every  portion  of  the  body,  whether  solid  or  fluid,  is  being 
subjected  to  the  magnifying  power  of  the  microscope,  and 
the  most  interesting  discoveries  are  being  made  in  each. 
The  various  fluids,  comprising  the  blood,  chyme,  chyle,  and 
the  different  secretions  and  excretions,  have  all  been  subjected 
to  this  mode  of  examination,  and  the  globules  whose  shape 
and  appearance,  with  other  characteristic  properties  of  the 
fluids,  were  hitherto  doubtful  and  disputed,  are  now  settled 
with  precision  and  accuracy. 

The  cell  of  Schwann,  and  epithelia,  which  are  likewise 
found  to  be  cells,  are  now  known  after  this  method,  to  exist 
upon  all  free  membranes,  mucous  and  serous,  as  well  as 
cuticular. 

All  these  details  of  modern  discoveries  are,  however, 


40  INTRODUCTION. 

noticed  in  their  appropriate  places  throughout  the  present 
work,  so  that  it  is  unnecessary  to  make  further  remarks  in 
this  place,  or  pursue  the  history  of  Anatomy  in  any  greater 
detail  at  present. 


RULES  FOR  DISSECTION  IN  GENERAL. 

1.  Let  each  student  supply  himself  with  an  apron,  made 
either  of  glazed  muslin  or  gum  elastic,  furnished  with 
sleeves,  and  reaching  from  the  neck  to  the  ankles. 

2.  He  should  provide  himself  with  a  dissecting  case,  in 
which  he  should  see  that  there  are  also  two  or  more  crooked 
needles,  for  sewing  up  the  parts  after  dissection.     He  should 
also  have  a  sponge,  as  cleanliness  is  of  the  utmost  import- 
ance to  neatness  of  dissection. 

3.  No  more  integument  should  he  turned  down  than  is 
necessary  to  fairly  expose  the  part  or  parts  under  exam- 
ination, as  the  dissection  is  liable  soon  to  become  dry  or 
putrefy — hence  it  is  always  necessary  to  replace  the  skin, 
or  cover  the  parts  with  a  cloth  of  several  thicknesses,  dipped 
in  water,  after  dissection. 

4.  The  knife  should  not  only  be  sharp,  but  be  in  the  best 
order  possible,  and  always  be  kept  so;  for  we  are  convinced, 
from  much  observation,  that  most  of  the  failures,  to  the 
making  a  neat  and  satisfactory  dissection,  arise  from  hav- 
ing dull  knives,  and  the  consequence  is  disappointment 
and  ultimate  dislike,  if  not   disgust,  for   any  dissection 
whatever — hence  we  .would  urge  each  student  to  furnish 
himself  with  a  "razor-strop  and  Arkansas  stone. 

5.  Hold  the  knife  as  you  would  a  writing  pen,  and  with 
the  other  hand  keep  the  skin  tense.     We  say  with  the 
other  hand,  for  the  fingers  are  always  to  be  preferred, 
when  you  can  use  them,  to  the  forceps.     The  skin  is  made 
tense,  or  put  on  the  stretch,  so  that  the  cellular  tissue  be- 


INTRODUCTION.  41 

neath  it,  and  covering  the  muscle,  shall  likewise  he  put  on 
the  stretch — then,  with  a  light  and  steady  stroke  of  the 
knife,  cut  in  the  direction  of  the  muscular  fihres,  and  close 
to  them,  so  as  to  he  sure  that  all  cellular  tissue  is  removed, 
and  the  muscle  thus  fairly  exposed.  Indeed,  if  the  student 
will  simply  recollect  to  keep  his  knives  in  first-rate  order, 
hold  the  integument  tense,  and  always  cut  in  the  course  of 
and  close  to  the  fihres  of  the  muscle,  he  cannot  fail  to  make 
a  neat  dissection. 


ORGANIZATION. 

The  structure  and  functions  of  the  organs  belonging  to 
living  beings  constitute  the  science  of  organization. 

The  vegetable  and  animal  creation  compose  its  two  great 
divisions. 

It  is  the  animal  organization  which  claims  our  attention. 

An  organ  is  regarded  to  be  any  portion  of  a  living  body 
capable  of  performing  a  complete  act  or  operation,  and  this 
act  of  the  organ  is  styled  its  function — thus  the  eye  is  the 
organ  of  sight— the  ear,  the  organ  of  sound  and  hearing,  &c. 

A  number  of  organs,  of  different  kinds,  conspiring  to  one 
end,  or  to  bring  about  one  result,  constitute  an  apparatus, 
as  the  apparatus  of  digestion,  the  lachrymal  apparatus,  &c. 

Organs  of  the  same  kind  form  a  system,  as  the  muscular, 
osseous  and  nervous  systems — and 

The  organs  collectively  have  been  styled  the  organism. 

A  variety  of  definitions  have  been  given  as  to  the  essen- 
tial nature  of  organization.  One  physiologist  defines  it 
to  be  the  "process  by  which  an  organized  being  is  formed, 
and  organism  the  result  of  such  process." 

By  another,  organization  is  made  to  consist  in  a  "pecu- 
liar form  and  structure,  containing  liquids  of  the  same 
nature  as  itself." 


42  INTRODUCTION. 

By  others  organization  is  considered  as  the  result  of 
life;  while  some  again  view  life  as  the  result  of  organiza- 
tion, each  alternately  being  made  cause  and  effect. 

The  celebrated  Bichat  describes  life  to  be  "the  sum  of 
the  functions  by  which  death  is  resisted." 

Another  physiologist  makes  life  to  consist  in  "the  phe- 
nomena peculiar  to  organized  bodies,  taken  as  a  whole." 

M.  Beclard  asserts  that  life  consists  essentially  in  one 
fact,  "that  all  organized  bodies,  during  a  determined  pe- 
riod, are  centres  penetrated  by  foreign  substances,  which 
they  appropriate  to  themselves,  and  from  which  issue  others 
that  become  foreign  to  them;  and  in  this  movement  of 
momentary  formation  the  matter  of  the  body  changes  con- 
tinually, but  its  form  still  remains."  He  adds,  that  life 
does  not  consist  in  a  re-union  of  molecules,  which  were 
before  separated,  as  occurs  in  the  case  of  chemical  attraction, 
nor  simply  in  an  expulsion  of  the  elements  previously  com- 
bined, as  in  that  which  is  produced  by  the  expulsive  action 
of  caloric,  but  in  a  movement  of  temporary  formation,  in 
which  some  elements  remain  united,  which  would  separate 
should  life  cease,  and  in  which  the  elementary  parts  are 
separated  without  the  action  of  caloric,  and  this  vital  ac- 
tion exists  only  in  organized  bodies ;  and  it  is  in  this 
"close  and  reciprocal  connection  of  organization  and  life 
that  is  to  be  found  the  reason  why  they  have  by  turns 
been  considered  the  cause  and  effect  of  each  other." 

M.  Beclard  very  justly  remarks  that  organization  and 
life  are  a  complex  idea — are  inseparable  in  their  connec- 
tion, and  that  life  is  "organization  in  action." 

Without  entering  into  the  abstract  question  of  what  is 
life? — a  very  unprofitable  and,  we  think,  useless  specula- 
tion— we  will  at  once  proceed  to  consider  the  fundamental 
elements  of  organization,  whose  analysis  is  its  only  correct 
definition. 

The  first  element  we  notice  as  fundamental  and  essential 
to  organization,  is  that  the  organized  body  shall  have  a 
definite  living  origin;  that  it  shall  be  born  of  a  parent  like 


INTRODUCTION.  43 

itself— grow,  attain  maturity,  decay  and  die,  after  the 
manner  of  the  heing  it  represents. 

Inorganic  bodies,  or  those  destitute  of  life,  on  the  con- 
trary, are  not  horn,  hut  simply  owe  their  origin  to  what 
are  termed  the  "general  forces  of  matter."  They  do  not 
grow,  hut  owe  their  increase  to  accident,  which  occurs 
whenever  particles,  for  which  there  is  an  affinity,  come 
within  the  sphere  of  their  attraction. 

Neither  do  they  attain  maturity,  decay,  or  die,  as  they 
are  destitute  both  of  a  living  birth  and  growth. 

The  second  fundamental  element  of  organization  is  a 
special  and  definite  form. 

This  we  see  every  where  throughout  the  vegetable  and 
animal  kingdoms.  Every  plant  and  flower — every  tree 
and  fruit — every  animal — every  genus  and  species,  each 
after  its  own  kind,  has  this  special  and  determinate  form, 
by  which  it  is  readily  distinguished  from  every  other 
form. 

Inorganic  bodies,  on  the  other  hand,  have  no  fixed  and 
determinate  form. 

The  third  element  is  a  definite  size. 

This  is  equally  true,  as  of  the  form,  in  all  the  individual 
genera  and  species,  both  vegetable  and  animal. 

We  see  them  all  to  have  a  special  and  determinate  size, 
and  though  there  may  be  occasional  dwarfs,  these  are  but 
exceptions,  which,  instead  of  overthrowing,  rather  confirm 
the  general  law. 

Inorganic  bodies,  it  is  well  known,  have  no  fixed  size, 
but  may  be  large  or  small,  and  constantly  changing,  just 
as  accident  makes  them. 

The  fourth  element  essential  to  organization  is  a  definite 
and  peculiar  structure,  or  a  regular  and  determinate  ar- 
rangement of  fibres,  forming  cells  or  areolae,  and  consti- 
tuting the  cellular,  areolar  or  spongy  tissue. 

This  peculiar  structure,  which  does  not  belong  to  the 
inorganic  body,  constitutes  the  principal  basis  of  all  or- 
ganization; it  is  viewed  as  the  primitive,  original  and 


44  INTRODUCTION. 

forming  part,  entering  into  the  whole  organization,  and 
constituting  its  most  extensive  and  universal  elementary 
solid. 

The  fifth  element  is  the  nutritive  fluid. 

This,  called  the  sap  in  the  vegetable,  is  the  white  or  red 
blood  in  the  animal. 

The  relative  proportion  of  this  fluid  varies  in  the  two 
kingdoms;  it  is  greater  in  the  animal  than  in  the  vegeta- 
ble, and  greater  in  youth  than  in  old  age. 

The  sixth  element  is  nutrition. 

This  belongs  to  the  whole  organic  world — from  the  blade 
of  grass  to  the  towering  oak — or  from  the  simple  worm  to 
the  huge  elephant — the  forms  of  nutrition  infinitely  vary- 
ing, but  the  result  the  same  in  all,  to  wit,  the  appropria- 
tion of  material  for  organization  and  its  preservation. 

It  is  -upon  this  universal  function  that  the  growth  of  all 
organic  bodies  depends — the  material  of  supply  being  from 
within  the  body. 

Now  nothing  like  nutrition  is  seen  in  the  inorganic  be- 
ing, for  when  it  grows  it  is  not  from  within  itself,  and  by 
a  complicated  process  of  action  as  occurs  in  the  organic 
body,  but  simply  by  the  addition  of  particle  to  particle  of 
similar  nature  from  without,  and  upon  its  superficies. 

A  seventh  element  is  the  complete  dependency  of  all  the 
parts  composing  every  organic  body,  and  this  is  most  es- 
pecially true  of  those  which  are  high  in  the  scale  of  animal 
formation. 

For  here  it  is  certain  death  to  any  part  to  be  separated 
from  the  body  of  which  it  forms  a  portion,  while  the  body 
itself  suffers,  in  turn,  in  proportion  to  the  importance  of 
the  part  it  has  lost,  and  if  it  be  any  of  the  essential  organs 
of  life,  death  is  as  instant  to  the  whole  body  as  to  these 
parts. 

It  is  true  some  animals,  very  low  in  the  scale,  as  the 
polypus,  may  be  separated  into  pieces,  and  each  piece  not 
only  has  the  power  to  live,  but  still  further  to  recreate 
itself  into  a  perfect  animal. 


INTRODUCTION.  45 

In  this  case  each  fragment  seems  to  possess  all  the  parts 
of  the  whole  animal,  each  having  the  generative  and  nu- 
tritive power  perfect;  there  then  seems  to  be  no  necessity 
that  any  of  these  parts  should  die. 

But  let  a  section  be  made  in  what  is  called  the  eye  or 
germ  of  these  animals,  and  death  is  as  certain  as  in  the 
higher  order;  for  here  the  chain  of  dependency  among  the 
several  parts,  making  each  fragment,  as  it  were,  complete 
in  itself,  is  broken,  and  this  essential  element  to  organic 
existence  as  certainly  destroyed. 

In  the  inorganic  body  we  observe  no  such  dependency 
among  its  several  parts.  Each  can  preserve  its  existence 
as  well  when  separated  from  all  the  other  parts  and  from 
the  whole  body  as  when  united. 

The  eighth  element  of  organization  is  a  limited  duration. 

Death  is  the  eternal  fiat  stamped  upon  all  living,  or- 
ganic bodies — they  carry  on  their  functions  for  a  definite 
period  of  existence  only,  during  the  active  and  early  exer- 
cise of  which,  the  body  grows,  attains  maturity,  and  then 
begins  to  languish,  decay  and  die. 

Inorganic  bodies,  on  the  other  hand,  have  no  fixed  pe- 
riod of  duration — their  existence  can  be  terminated  at  any 
moment,  either  by  mechanical  violence  breaking  down  their 
several  parts,  or  by  the  play  of  chemical  affinity  destroy- 
ing their  nature,  or  if  none  of  these  circumstances  operate, 
their  duration  may  be  unlimited. 

These  are  the  different  elements  which  are  regarded  as 
the  most  essential  in  forming  organization. 

We  now  proceed  to  notice  the  principal  of  those  most  es- 
sential in  preserving  organization — which  consist  of, 

1.  Atmospheric  air.  3.  Water. 

2.  Food.  4.  Heat. 

These  elements  are  the  vital  stimuli,  whose  presence  is 
indispensable  to  the  existence  of  all  kinds  of  organization, 
whether  animal  or  vegetable. 

In  the  higher  order  of  animals,  the  necessity  of  breath- 


46  INTRODUCTION. 

ing,  taking  food  and  drink,  and  having  a  proper  tempera- 
ture, is  plainly  manifest. 

Though  there  are  some,  it  is  true,  which  have  the  power 
of  apparently  suspending  their  functions  for  a  while  and 
entering  into  a  torpid  state — and  consequently,  remaining 
in  a  great  measure  without  the  influence  of  the  vital  stim- 
uli; they  nevertheless  exist,  and  again  revive  in  their 
former  activity. 

This,  however,  by  no  means  subverts  the  general  law  of 
the  necessity  of  the  presence  of  the  vital  stimuli  to  organic 
existence — for  atmospheric  air  and  a  certain  amount  of  tem- 
perature is  present  in  sufficient  quantity  to  account  for  the 
remaining  vitality  which  is  found  to  have  been  present,  and 
again  to  revive  on  the  re-application  of  the  balance  of  the 
vital  stimuli. 

Now,  between  these  two  series  of  elements — the  one  for 
forming  and  the  other  for  preserving  organization,  nature 
has  established  the  most  intimate  relations — relations  close, 
fixed  and  determinate — constituting  so  many  laws  which 
are  essential  to  be  obeyed  for  preserving  the  integrity  of 
organization. 

These  relations  or  laws  consist  essentially  in  the  nice 
adaptation  of  the  one  class  of  these  elements  to  the  other, 
when  in  their  natural  state  of  integrity. 

Examples  of  violation  of  these  relations  are  seen  when 
carbonic  acid  gas,  sulphuretted  hydrogen,  or  any  other  nox- 
ious gas  is  taken  for  atmospheric  air,  or  when  putrid  food 
and  alcohol  are  taken  in  the  place  of  bread  and  water. 

The  result  of  these  violations,  in  destroying  organiza- 
tion, health  and  life,  is  familiar  to  all,  and  therefore  it  is 
unnecessary  to  enter  into  any  detail. 


INTRODUCTION.  47 


VARIETIES  OF  ANIMAL  ORGANIZATION. 

Nature  it  seems  has  constructed  the  animal  kingdom  upon 
four  great  models  or  types. 

1.  The  Kadiata — forming  the  zoophytes. 

2.  The  Articulata — worms,  insects,  &c. 

3.  The  Mollusca — shell-fish,  &c. 

4.  The  Vertehrata — having  a  spine. 

The  Eadiata,  so  called  from  their  resemblance  to  a  ra- 
diated flower  or  star,  are  of  simple  structure,  and  described 
as  having  no  distinct  nervous  system,  TIO  organs  of  sense, 
no  heart,  and  having  white  blood. 

This  class  includes  the  polypus,  hydratid,  coral,  sponge, 
star-fish,  infusoria,  &c. 

The  Articulata  are  a  step  higher  in  organization,  for  here 
are  found  nervous  ganglia,  forming  a  longitudinal  chain 
along  the  median  line  of  the  body.  The  body  itself  is  di- 
vided into  rings,  which  feature  gives  the  name  to  the  Class, 
and  has  a  protection  or  kind  of  skeleton  exteriorly  of  hard- 
ened skin,  or  horny  covering,  as  seen  in  the  insect  and  lob- 
ster. The  blood  is  also  generally  white,  and  there  is  no 
heart,  but  simply  a  vessel  running  along  the  back  called 
the  dorsal  vessel.  There  are  senses,  but  they  are  more  or 
less  incomplete. 

This  Class  includes  the  Crustacea,  as  the  Crab,  &c.,  the 
Arachnides  or  Spiders,  the  Annelides  or  Worms,  and  In- 
sects. 

The  Mollusca,  as  their  name  implies,  have  the  body  soft, 
and  like  the  Articulata,  have  nervous  ganglia ;  but,  instead 
of  being  united,  these  are  found  scattered  throughout  the 
body,  and  not  in  a  chain  along  the  middle  line.  The  senses 
are  also  incomplete,  the  blood,  white;  but  here  we  find  a 
heart. 

There  are  no  rings,  no  external  skeleton,  but  simply  a 
stony  crust  or  covering  constituting  the  shell. 


48  INTRODUCTION. 

The  Snail,  Oyster,  Nautilus,  &c.,  are  specimens  of  this 
Class. 

The  Vertebrata  form  the  next  and  highest  step  in  the 
animal  kingdom. 

This  Class,  deriving  its  name  from  all  its  members  having 
vertebras  or  a  spine,  is  principally  characterized  by  the 
body  being  symmetrical,  the  nervous  system  being  composed 
of  a  brain  and  spinal  marrow,  as  well  as  nervous  ganglia, 
by  the  blood  being  red  and  warm,  and  there  being  a  heart 
and  five  senses. 

These  four  divisions,  constituting  the  four  great  varieties 
of  animal  organization,  have  each  many  subdivisions  into 
the  different  orders,  genera  and  species. 

Each  of  these  varieties,  with  its  various  subdivisions, 
as  already  stated  in  reference  to  organization  in  general, 
owes  its  existence  and  preservation  entirely  to  the  fixed 
relation  established  between  its  peculiar  structure  and  one 
or  more  of  the  fundamental  elements  of  preservation. 

We  shall  take  the  division  of  the  vertebrata  by  way  of 
illustration. 

The  vertebrated  Class  has  four  principal  branches — 
Fishes,  Keptiles,  Birds,  and  Mammalia. 

Now  the  organization  of  Fishes  is  constructed  with  special 
reference  to  the  element,  water — the  whole  exterior  and 
interior  form,  as  the  fins,  gills,  air-bladder,  &c.,  all  clearly 
show  that  water  is  their  natural  element — and  that  not- 
withstanding they  require  air  and  food,  and  have  more  or 
less  relation  with  these  principles,  yet  the  great  and  prom- 
inent relation  is  with  water,  without  which  the  whole 
variety  would  soon  cease  to  live,  though  there  might  be 
free  supply  of  both  air  and  food. 

Eeptiles  have  a  modification  of  structure  which  adapts 
them  to  both  water  and  air,  in  each  of  which  some  of  them 
alternately  live,  as  in  the  cases  of  the  turtle,  crocodile, 
frog,  &c. 

Birds  being  made  for  flight,  have  their  special  relations 
with  the  atmosphere.  This  is  their  essential  and  peculiar 


INTRODUCTION.  49 

element,  as  their  whole  organization  shows.  For  we  find 
the  exterior  of  the  body  covered  with  feathers— the  remark- 
ahle  property  of  which  is  lightness — nicely  adapted  for 
sustaining  them  in  the  air.  The  lungs  occupy  the  abdom- 
inal as  well  as  thoracic  cavity,  there  being  no  diaphragm, 
and  thus,  extending  the  almost  entire  length  of  the  trunk, 
form  as  it  were  so  many  bladders,  which  being  filled  with 
air,  give  the  body  the  same  specific  gravity  with  this  fluid — 
consequently  placing  the  animal  in  the  most  perfect  rela- 
tion for  moving  and  living  in  this  element.  The  skele- 
ton likewise  receives  air,  thus  rendering  the  body  still 
lighter — and  so  with  every  other  part,  each  being  adapted 
the  one  to  the  other,  and  the  whole  specially  to  the  atmos- 
phere, the  fundamental  element  of  this  variety  of  organi- 
zation— for  a  bird  can  no  more  live  under  water,  than  a 
fish  can  in  the  air. 

The  class  mammalia,  divided  into  the  carnivorous  and 
herbivorous  animals,  have  organizations  formed  with  spe- 
cial reference  to  food — the  one  of  these  living  on  flesh — 
the  other  on  grass,  fruits  and  grain,  and  the  structure  in 
each,  as  most  distinctly  seen  in  that  of  the  teeth,  stomach 
and  alimentary  tubes,  corresponds  to  the  particular  kind 
of  food  on  which  they  respectively  subsist — and  so  fixed  is 
this  relation  between  the  kind  of  food  and  the  organization 
adapted  to  it,  that  to  change  the  food  of  the  one  class  for 
that  of  the  other,  would  be  death  to  both. 

The  same  may  be  said  in  reference  to  climate.  The  polar 
bear  could  no  more  live  under  the  equator,  than  the  ourang- 
outang  could  under  the  north  pole — each  having  its  organ- 
ization made  with  special  reference  to  temperature. 

Now,  in  all  these  instances  we  find  the  variety  of  or- 
ganization depends  upon  fixed  relations — established  more 
particularly  with  one  of  the  fundamental  elements  than 
another — which  particular  relationship  constitutes  so  many 
special  laws  for  each  variety — violation  of  which  in  each 
case  is  destructive  to  organization,  and  that  just  in  propor- 
tion to  the  offence.  But  these  special  laws  by  no  means 
4 


50  INTRODUCTION. 

conflict  with  or  exempt  from  the  operation  of  the  general 
laws  to  which  all  organization  is  subject. 

The  last  example  of  variety  we  have  to  offer,  is  the 
organization  of  man. 

Man,  it  is  well  known,  stands  at  the  top  of  the  animal 
scale — forms  the  highest  and  most  perfect  link — is  the  most 
complex  and  varied — has  the  most  extensive  and  multi- 
plied relations,  and  the  greatest  number  of  properties  and 
powers.  And  as  organization  differs  and  becomes  complex 
in  proportion  to  the  number  and  variety  of  its  properties 
and  relations,  we  find  in  man's  formation  a  miniature  rep- 
resentation of  all  we  see  in  the  inferior  animal  world — 
with  the  addition  of  his  own  distinguishing  and  surpassing 
structure,  adapted  to  his  intellectual  and  moral  powers. 

CONSTITUENTS   OF  HUMAN  ORGANIZATION. 

Analysis  resolves  the  constituents  of  human  organization 
into, 

1.  Chemical. 

2.  Organic  elements. 

The  chemical  consist  of  oxygen,  hydrogen,  carbon,  nitro- 
gen, sulphur,  phosphorus,  chlorine,  fluorine,  potassium, 
aluminum,  calcium,  sodium,  magnesium,  silicium,  iron, 
manganese,  to  which  some  have  added  titanium,  lead, 
copper,  iodine  and  bromine. 

Of  these,  nitrogen  and  oxygen  are  found  in  a  simple, 
pure  state — both  in  the  blood,  and  nitrogen  in  the  intesti- 
nal gases. 

The  rest  exist  as  binary,  ternary,  or  quartenary  com- 
pounds. The  binary  are  inorganic  compounds,  and  con- 
sist of, 

1.  Water,  composing  the  largest  portion  of  the  fluids  of 
the  body,  entering  into  the  solids  and  producing  the  differ- 
ent degrees  of  softness. 

2.  Carbonic  acid,  found  in  the  blood,  exhaled  from  the 
lungs,  skin,  urine — as  well  as  united  with  lime,  potash, 


INTRODUCTION.  51 

soda,  forming  the  carbonate  of  lime  in  the  teeth,  bones, 
cartilage,  &c. 

Carbonate  of  potass  a  in  the  serum. 

Carbonate  of  soda  in  the  serum,  hile,  saliva,  tears,  sweat, 
mucus,  teeth,  hone,  cartilage,  &c. 

There  are  also  carbonates  of  ammonia  in  the  urine,  and 
of  magnesia  in  the  grease  of  the  skin. 

3.  The  union  of  phosphoric  acid  with  lime,  soda,  ammo- 
nia, &c.,  as,  for  example,  the  phosphate  of  lime  composing 
by  far  the  greater  bulk  of  the  bones,  and  also  existing  in 
the  teeth,  cartilages,  and  pineal  gland. 

The  phosphates  of  soda  and  ammonia  are  seen  in  the 
urine,  the  blood,  saliva,  tears,  &c. 

4.  The  compounds  of  Chlorine,  as  those  with  hydrogen 
sodium,  potassium,  ammonium,  and  calcium,  forming  chlo- 
rides of  these  bodies,  are  seen  in  the  gastric  juice,  blood, 
brain,   muscle,   bone,   cartilage,   dentine,   pigment,   milk, 
saliva,  sweat,  &c. 

5.  Sulphates  -of  potash,  soda  and  lime,  are  seen  in  the 
cartilage,  gastric  juice,  urine,  bile,  sweat,  hair,  cuticle,  saliva. 
And  other  binary  compounds  are  also  discovered  to  exist, 
as  the  fluoride  of  calcium  and  alumina,  in  enamel  of  the 
teeth,  silica  and  oxide  of  manganese  in  the  hair,  oxide  of 
iron,  in  hematine  and  black  pigment,  oxide  of  titanium, 
and  sulpho-cyanide  of  potassium  in  the  saliva. 

The  ternary  and  quarternary  compounds  include  the 
Organic  Elements,  whose  distinguishing  feature  is,  that 
they  are  only  found  in  living  bodies,  whether  animal  or 
vegetable,  and  that  the  most  prominent  of  them  possess  an 
additional  element,  not  found  in  the  inorganic,  which  is 
nitrogen,  upon  whose  presence  depends  the  rapidity  with 
which  some  structures  become  putrid,  or  pass  into  decom- 
position. This  remark  refers  more  particularly  to  the  ani- 
mal compounds — the  vegetable  products,  with  very  few 
exceptions,  are  deficient  in  nitrogen.  The  Organic  Elements 
having  nitrogen  are, 


52  INTRODUCTION. 

1.  Protein,  6.  Globulin, 

2.  Albumen,  7.  Spermatin, 

3.  Fibrin,  8.  Mucus, 

4.  Casein,  9.  Lachrymal  matter,        41 

5.  Pepsin,  10.  Keratin. 

Protein  is  regarded  as  the  basis  of  all  the  other  elements, 
is  found  in  every  animal,  and  it  is  said  that  no  tissue  or 
organ  is  destitute  of  its  presence. 

It  can  be  obtained  by  boiling  albumen  in  a  weak  so- 
lution of  caustic  potass,  and  then  precipitating  with  an 
acid. 

The  gluten  of  wheat-flour,  after  the  starch  is  washed 
away,  and  treated  in  the  same  manner,  also  yields  protein. 

Thus  obtained,  in  the  moist  state  it  is  gelatinous,  without 
smell  or  taste,  insoluble  in  water,  ether  or  alcohol,  but 
soluble  in  dilute  acid.  When  dry,  it  is  hard,  brown,  and 
brittle. 

According  to  Mulder,  its  discoverer,  it  is  chemically 
composed  in  atomic  weights,  of  carbon  40,  hydrogen  31, 
nitrogen  5,  oxygen  12. 

Albumen  is  found  in  the  serum  of  the  blood,  lymph,  chyle, 
&nd  a  beautiful  specimen  is  seen  in  the  white  of  the  egg. 
It  is  one  of  the  special  elements  of  the  brain,  and  exists 
also  in  pus,  and  many  of  the  secretions. 

It  is  yellow  and  .brittle  when  dry,  coagulates  by  heat, 
creosote,  spirits  of  wine,  and  some  acids;  is  soluble  in 
water,  and  forms  an  insoluble  compound  with  corrosive 
sublimate,  sugar  of  lead,  alum,  nitric  and  tannic  acids. 

It  is  composed,  according  to  Gay  Lussac  and  Thenard,  of 

Nitrogen,  15.705, 

Carbon,  52.883, 
Hydrogen,         *7.540, 

Oxygen,  23.8*72,  in  an  hundred  parts. 

Fibrine  constitutes  the  basis  of  the  muscular  system, 
exists  in  the  blood,  chyle,  lymph,  and  in  abundance  upon 


INTRODUCTION.  53 

inflamed  surfaces,  is  soluble  in  the  blood,  from  which  when 
drawn  it  readily  coagulates. 

It  can  be  obtained  from  the  blood,  by  stirring  it  briskly 
with  a  rough  stick,  when  it  will  appear  in  the  form  of  fibres 
or  threads.  Vegetable  acids,  their  salts,  and  caustic  alkalies 
prevent  coagulation. 

Its  chemical  elements  are 

Nitrogen,  19.934, 

Carbon,  53.360, 
Hydrogen,     V.021, 

Oxygen,  19.685,  in  the  hundred  parts. 

Casein  exists  most  abundantly  in  milk,  but  is  also  found 
in  the  blood,  saliva,  bile,  pancreatic  fluid,  lens,  and  else- 
where. In  solution  it  is  of  a  pale  yellow,  coagulates  by 
heat,  acids,  alcohol,  and  rennet. 

It  is  soluble  in  water,  and  in  this  state  has  the  consist- 
ence of  mucilage. 

When  dried  it  is  of  an  amber  color,  and  very  friable. 

Cheese  is  composed  of  dried  casein  and  butter.  Accord- 
ing to  Mulder  its  chemical  elements  are  in  one  hundred 
parts — 

Nitrogen,     15.95,  Hydrogen,      6.9T, 

Carbon,        55.10,  Oxygen,         21.62. 

These  four  organic  elements  constitute  the  great  proxi- 
mate principles  of  animal  formation. 

And  the  albumen,  fibrin,  and  casein,  seem  to  be  formed 
from  the  protein,  or  more  properly  speaking,  only  differ 
from  it  by  having  in  addition  a  little  sulphur  and  phos- 
phorus in  combination. 

Protein,  it  has  been  stated,  is  always  found  in  the  albu- 
minous vegetables,  and  has  the  same  constitution  in  them 
as  in  the  animal  frame.  Hence,  we  can  readily  under- 
stand how  and  why  it  is,  that  vegetable  matter  is  so  read- 
ily converted  into  animal,  and  so  important  in  sustaining 
life. 


54  INTRODUCTION. 

The  other  elements  not  so  extensively  diffused,  we  will 
briefly  notice.  They  are  as  follows : 

Pepsin  was  discovered  by  Schwann  in  the  gastric  juice, 
the  parietes  of  the  follicles  and  glands  of  the  stomach,  and 
may  be  obtained  by  macerating  the  stomach  of  an  animal. 
"With  an  acid  it  readily  dissolves  albumen  and  fibrin — 
resembles  very  much  albumen — and  is  considered  the  ac- 
tive agent  in  digestion,  the  prime  element  in  converting 
the  food  into  chyme. 

Chemical  Analysis  makes  Pepsin  consist  of  Oxygen  10, 
Hydrogen  32,  Nitrogen  8,  Carbon  48. 

Globulin  exists  in  the  envelopes  of  the  blood  corpuscles, 
and  resembles  albumen.  Simon  regards  it  as  casein  united 
with  hgematin. 

Spermatin  is  found  in  the  seminal  fluid,  and  looked  upon 
as  probably  only  fibrin. 

Mucus  is  furnished  by  the  mucous  glands.  It  is  insoluble 
in  water,  transparent  when  evaporated  to  dryness,  is  soluble 
in  acids,  does  not  coagulate  by  heat,  is  precipitated  by 
tannin,  and  is  always  found  united  with  the  cast-off  epithe- 
lium and  pus. 

Lachrymal  matter.  This  is  found  in  the  tears  after  evap- 
oration, and  is  regarded  as  insoluble  mucus. 

Keratin  is  so  named  from  being  found  in  the  nails,  hair, 
and  cuticle,  though  its  character  is  not  yet  fully  determined. 

EXTRACTIVE  ELEMENTS. 

When  protein  and  the  salts  are  removed  from  animal 
matter,  what  is  left  is  called  Extractive  matter. 

This  is  found  pretty  generally  diffused  through  the  body, 
but  most  abundant  in  muscle. 

The  dried  extract  of  flesh,  if  treated  with  water,  diluted 
alcohol,  or  pure  alcohol,  forms  either  a  water  extract,  spirit 
extract,  or  alcoholic  extract. 

The  spirit  extract  is  termed  ozmasome,  (from  o<y^,  smell, 
and  ^ajuof,  soup,)  because  it  gives  the  flavor  to  soups. 


INTRODUCTION.  55 

Ptyalin  or  Salivin,  is  a  substance  found  in  saliva,  and 
Kreatin  in  the  fluids  of  meat. 

Gelatin — colla  or  glue — abounds  in  the  cellular  tissue, 
bones,  cartilages,  tendons  and  ligaments. 

It  is  obtained  by  boiling,  by  which  means  it  is  soluble, 
and  on  cooling  becomes  a  jelly. 

Its  chemical  elements,  according  to  Mulder,  are  in  one 
hundred  parts,  Nitrogen  18.350,  Carbon  50.548,  Hydrogen 
6.477,  Oxygen  25.125. 

Chondrin  forms  the  basis  of  the  cartilages;  it  resem- 
bles gelatin,  and  exists  in  the  cartilages  of  the  ear,  nose, 
ribs,  &c. 

Its  chemical  composition  is  made  to  consist  of  Nitrogen 
14.44,  Carbon  49.56,  Hydrogen  6.63,  Oxygen  28.59,  Sulphur 
0.38. 

Both  Chondrin  and  Gelatin  also  contain  phosphate  of 
lime. 

Hcematin  forms  the  coloring  matter  of  the  blood,  and  is 
found  in  the  envelopes  of  the  colored  globules.  It  con- 
tains iron,  and  is  soluble  in  alkalies.  When  dry  it  is  dark 
brown,  and  without  taste  or  smell. 

Pyin,  as  its  name  implies,  is  found  in  pus,  and  resembles 
gelatin. 

Bile. — The  essential  principle  of  bile,  according  to  Berze- 
lius,  is  bilin,  which,  when  dry  and  in  a  pure  state,  is  with- 
out color,  transparent,  very  soluble  in  water,  bitter  in 
taste,  not  crystallizable,  and  decomposable  by  acids.  It 
forms,  with  acids  and  bases,  soluble  compounds,  and  shows 
neither  acid  nor  alkaline  reaction. 

It  is  regarded  as  resinous,  and  contains  a  biliary  sugar. 

Urea  is  found  chiefly  in  the  urine.  It  is  also  discovered 
in  the  blood  and  its  secretions,  when  there  is  disease  of  the 
kidneys.  It  is  obtained  by  adding  nitric  acid  to  the  urine 
after  its  evaporation  to  the  consistence  of  sirup,  when 
there  is  produced  the  nitrate  of  urea.  The  nitric  acid  is  re- 
moved by  the  carbonate  of  barytes,  and  the  urea  dissolved 
in  alcohol,  which  latter  is  driven  off  by  evaporation. 


56  INTRODUCTION. 

Urea  is  described  as  colorless,  and  presenting  four-sided 
prisms,  or  long,  "  silky,  shining  needles."  It  is  without 
smell  and  has  neither  acid  nor  alkaline  reaction. 

Uric  add  is  found  mostly  in  the  urine  of  carnivorous 
animals  or  those  which  feed  on  flesh,  and  is  also  seen  in 
urinary  calculi,  and  gouty  concretions.  The  excrements  of 
birds  consist  almost  entirely  of  this  acid,  united  with  am- 
monia, constituting  the  guano  of  commerce.  It  is  precip- 
itated at  a  low  temperature,  aiid  the  precipitate  is  at  first 
grey,  then  a  pale  rose  color — on  drying  it  assumes  the  form 
of  scales — this  acid  readily  dissolves  urea. 

Animal  matters  which  are  destitute  of  nitrogen.  These 
consist, 

1.  Sugar  of  milk. 

2.  Lactic  acid. 

3.  Fats. 

Sugar  of  milk,  according  to  chemistry,  composes  two- 
fifths  of  the  solid  constituents  of  human  milk.  It  is  ob- 
tained from  the  whey  by  evaporation  and  crystallization, 
after  removing  the  casein  and  fat. 

It  is  easily  soluble  in  water — harder  than  cane-sugar, 
and  slightly  sweet.  Its  specific  gravity  is  1.  543.  Its  crys- 
tals form  four-sided  prisms. 

Liebig  makes  its  elements  consist  of  carbon,  12  atoms, 
hydrogen  24,  oxygen  2. 

Lactic  acid  is  found  in  all  the  fluids  and  secretions  of  the 
body.  It  exists  in  a  free  state  in  the  milk,  sweat,  urine, 
and  muscles,  and  in  combination  with  lime,  potash,  soda 
and  magnesia — holds  phospate  of  lime  in  solution,  and  is 
supposed  to  predominate  when  this  element  is  deficient  in 
the  bones.  It  is  a  strong  acid,  without  smell  or -color,  co- 
agulates albumen  and  casein,  and  is  decomposed  by  heat. 
Its  salts  are  soluble  in  water,  and  crystallizable. 

Fats  are  found  free  in  the  cellular  tissue  and  medulla 
of  bones,  or  in  combination  with  other  substances,  as  in  the 
milk,  brain,  hair,  wax  of  the  ear,  pus,  &c. 


INTRODUCTION.  57 

They  are  insoluble  in  water — but  soluble  in  hot  alcohol 
and  ether,  forming  compounds  of  carburetted  hydrogen, 
with  some  oxygen. 

Some  of  them  by  combining  with  an  alkali,  form  soap — 
and  with  the  oxyds  of  lead,  plasters. 

This  is  effected  by  the  acids  they  contain  uniting  with 
the  base  and  forming  salts. 

Of  the  saponifiable  fats,  there  are  three  substances  re- 
cognized as  forming  a  base. 

1.  Glycerin.  2.  Oxyd  of  Cetyl.  3.  Cerin. 

The  first  is  the  base  of  human  fat,  and  is  extensively 
diffused  among  animals — the  second  belongs  to  spermaceti 
and  the  third  to  wax. 

Glycerin  is  obtained  by  boiling  fat  with  oxyd  of  lead.  It 
is  said  to  be  sweet,  yellow,  without  odor,  soluble  in  water, 
but  not  soluble  in  ether. 

The  acids  combining  with  this  base  are  the  stearic,  mar- 
garic  and  oleic — forming  stearin,  margarin  and  olein,  sub- 
stances known  familiarly  as  suet,  lard  and  oil. 

The  union  of  these  two  classes  of  elements  in  varied  pro- 
portions, constitutes  the  solids  and  fluids  of  the  body. 

DEVELOPMENT  OF   ORGANIZATION. 

Organization,  consisting  as  it  does  of  a  variety  of  parts, 
we  will  briefly  remark,  advances  by  a  series  of  steps — not 
simultaneously,  but  in  a  regular  and  definite  succession,  at 
regular  and  definite  periods — after  a  regular  and  estab- 
lished form — and  in  obedience  to  established  fundamental 
laws. 

Special  ^development  will  be  noticed  in  the  examination 
of  individual  organs. 

Table  of  differences  betiveen  dead  inorganic,  and  living  or- 
ganized bodies,  as  given  by  M.  Magendie. 

These  differences  consist  in  the  form,  composition  and 
laws  which  govern  them. 


58 


INTRODUCTION. 


Inorganic  bodies. 
Living  bodies. 


FORM. 

[  Form  angular. 

[  Volume  indeterminate. 

]  Form  rounded. 

1  Volume  determinate. 


COMPOSITION. 


INORGANIC    BODIES. 


L1TING    BODIES. 


Sometimes  simple. 

Karely  formed  of  more  than 
three  elements. 

Constant. 

Each  part  can  exist  inde- 
pendent of  the  rest. 

Capable  of  being  decomposed 
and  restored. 


Never  simple. 

Having  at  least  four  elements, 
often  eight  or  ten. 

Variable. 

Each  part  more  or  less  de- 
pendent on  the  rest. 

Capable  of  being  decomposed, 
but  not  of  being  restored. 


LAWS  WHICH  GOVERN  THEM. 

INORGANIC    BODIES.  LIVING    BODIES. 


Entirely  submissive  to  the 
laws  of  attraction  and 
chemical  affinity. 


Partly  submissive  to  attrac- 
tion and  chemical  affinity. 

Partly  governed  by  an  un- 
known power. 


ANATOMY, 


to  dissect.) 


Divisions.—  The  world  of  life  being  divided  into  two 
great  departments,  vegetable  and  animal,  the  beings  of 
each,  when  examined  by  dissection,  cause  the  division  of 
Anatomy  into 

1.  Vegetable  Anatomy,  or  Phytotomy. 

2.  Animal  Anatomy  or  Zootomy. 

Animal  Anatomy  is  divided  into 

1.  Human  Anatomy. 

2.  Comparative  Anatomy. 


INTRODUCTION.  59 

The  former  treats  of  the  organs  of  the  human  body — 
the  latter  of  those  of  the  inferior  animals. 
Human  Anatomy  is  divided  into 

1.  General  Anatomy,  which  takes  up  the  same  tissue, 
and  follows  it  throughout  the  system,  into  every  organ, 
and  examines  it  in  all  its  relations  and  properties,  physical, 
organic,  and  vital.     The  celebrated  Bichat  is  the  founder 
of  General  Anatomy. 

2.  Special  Anatomy,  which  takes  up  each  organ,  one  by 
one,  and  minutely  examines   all   the  different  tissues  of 
which  it  is  composed  at  the  same  time,  showing  the  situa- 
tion of  each  organ,  its  form,  size,  interior  structure  and 
relations. 

The  difference  between  these  two  kinds  of  Anatomy  is 
thus  explained  by  Bichat  : 

Chemistry,  says  he,  has  its  simple  bodies,  as  heat,  light, 
oxygen,  hydrogen,  carbon,  &c.,  whose  various  combina- 
tions form  all  the  bodies  we  see  on  the  face  of  the  earth. 
So  Anatomy  has  its  simple  tissues,  by  whose  varied  combi- 
nations all  the  different  organs  of  animals,  as  well  as  the 
human  body,  are  formed. 

There  are  other  divisions  of  Anatomy,  as 

Surgical  Anatomy,  which  treats  of  those  portions  of  the 
body  having  special  reference  to  the  treatment  of  Surgical 
diseases. 

Eegional  or  Topographical  Anatomy,  when  all  the  organs 
in  any  particular  region  or  section,  are  examined  collec- 
tively; and 

Pathological  Anatomy,  when  the  organs  are  examined  in 
a  state  of  disease. 


PART  FIRST. 


THE  ALPHABET  OF  ANATOMY, 

OK 

ELEMENTARY  TISSUES  OF  THE  BODY. 


PART   FIRST. 

^ 

CHAPTER  I. 

ORIGIN    OF   THE  TISSUES. 

TISSUE  is  a  phrase  applied  to  an  elementary  part,  or 
structure  of  the  body,  and  consists  in  a  peculiar  arrange- 
ment of  fibres. 

An  Organ  is  composed  of  several  Tissues. 

The  Nucleated  Cell,  (fig.  !_,)  from  observations 

Owith  the  microscope,  first  announced  by  Schwann 
in  1838,  is  now  generally  received   as  the  ele- 
^       •    mentary,  or  first  form,  in  which  animal  matter  is 
™  developed,  and  from  which,  as  the  basis,  all  or- 

ganic structures,  whether  vegetable  or  animal,  are  formed. 
This  cell  is  described  as  a  vesicle  of  delicate  membrane, 
containing  a  fluid,  and  a  minute  dark  nucleus,  called  Cyto- 
blast,  or  Cell-germ  (from  xutoj,  cell,,  and  pKwtos,  germ,)  and 
is  surrounded  by  an  amorphous  substance,  either  solid  or 
fluid,  called  blastema  or  cytoblastema,  from  which  the  cell 
itself  springs. 

The  Nucleus  presents  a  round  or  oval  shape,  somewhat 
flattened,  its  surface  smooth  or  granular,  of  a  yellowish 
red,  or  without  color,  and  having  a  diameter  from  the  four- 
thousandth  to  the  two-thousandth  part  of  a  line. 

FIG.  1.  Represents  the  Cell  with  its  contained  Nucleus,  and  the  Nucleus 
without  any  Cell. 


64  ORIGIN  OF  THE  TISSUES. 

It  arises,  as  is  supposed,  by  the  blending  together  of  the 
granules  about  a  central  point,  as  they  are  being  deposited 
from  the  amorphous  mass — their  common  birth-place  and 
origin. 

This  mode  of  origin  and  development  has  been  observed 
in  the  egg  of  animals  and  germ  of  plants. 

The  Nucleated  Cell,  thus  formed,  multiplies  in  number, 
and  blends  and  coalesces  with  the  newly  formed  cells,  and 
by  various  metamorphoses  ultimately  forms  all  the  different 
tissues  of  which  the  body  is  composed. 

The  cells  increase,  either  by  the  origin  of  new  ones,  singly 
— and  independently  the  one  of  the  other — or  by  the  pri- 
mary cell  developing  within  itself  a  series  of  new  secondary 
Cells,  which,  in  their  turn,  give  origin  to  others,  and  so 
on,  successively. 

The  Hair,  Nails,  and  inflammatory  exudation,  are  cited 
as  examples  of  the  first  mode  of  increase — and  the  Liver, 
and  pathological  growths,  as  scirrhus,  as  specimens  of  the 
second. 

The  Cells,  as  they  are  passing  through  their  various 
stages  of  development,  to  the  formation  of  the  different 
tissues,  necessarily  change  their  shape,  position,  contents, 
and  relations;  as,  for  instance,  in  some  Tissues  they  pre- 
serve their  independence,  and,  by  being  situated  the  one 
upon  the  other,  become  thereby  flattened,  or  pointed  and 
elongated:  others  increase  in  size,  as  the  fat  Cells,  or  di- 
minish in  size,  as  the  lymph  corpuscles  when  changed  into 
blood  corpuscles;  or  lose  their  Nucleus,  as  in  the  mature 
blood-corpuscle;  or  have  their  parietes  thickened,  as  the 
Cartilage  Cells. 

The  Cells,  in  most  of  the  Tissues,  come  together  and  coa- 
lesce. By  this  process  the  cavities  of  the  Cells  present  two 
conditions;  in  the  one  case  they  remain  open,  in  the  other 
they  disappear. 

Examples  of  the  remaining  Cell  cavity  are  seen  in  true 
Cartilage  and  Osseous  Tissue,  where  the  thickened  cell  walls 
are  blended  together,  or  their  parietes,  in  contact  with  one 


PROPERTIES  OP  THE  TISSUES.  65 

another,  give  way  and  form  continuous  tubes,  as  those  of  the 
renal  and  seminal  tubuli. 

In  the  second  case,  where  the  Cell  cavity  disappears,  the 
parietes  of  the  Cells  lie  flat  together,  forming  solid  laminae, 
as  in  membrane. 

The  Nuclei  of  the  Cells  elongate  and  coalesce,  and  form 
nucleus  fibres,  which  differ  from  the  Cell  fibres  by  being 
insoluble  in  acetic  acid. 

PHYSICAL  PROPERTIES  OF  THE  TISSUES. 

The  different  Tissues  possess  the  properties  of  density, 
color  and  consistency,  as  matter  in  general:  some  of  them 
also  have  elasticity  and  pliability,  properties  which  are  due 
to  the  presence  of  water. 

VITAL  PROPERTIES   OF  THE  TISSUES. 

The  vital  properties  are  termed  Contractility,  Sensibility, 
and  what  is  called  the  Formative  force.  Contractility  mani- 
fests itself  in  the  shortening  of  living  tissues  under  the 
influence  of  mechanical  or  chemical  stimuli,  or  the  stimu- 
lus from  the  nerves,  as  seen  in  the  muscles.  Voluntary 
contractility  belongs  to  the  muscles  of  locomotion,  which 
contract  through  the  agency  of  the  brain.  There  is  another 
kind  of  contraction,  permanent  in  its  character,  arising  from 
a  great  degree  of  heat,  and  is  a  sort  of  crisping  not  to  be 
confounded  with  vital  contraction. 

Sensibility  of  the  tissues  is  due  to  the  nerves  and  their 
connection  with  the  brain,  and  the  amount  of  sensibility 
which  any  tissue  may  possess  is  measured  by  the  number  of 
its  sentient  nerve  fibres. 

The  Formative  force,  called  also  the  Plastic  or  Assimila- 
tive force,  is  that  power  in  the  different  tissues  to  form  them- 
selves out  of  materials  altogether  unlike  those  of  which  they 
are  severally  composed;  and  formation,  assimilation,  and 
nutritious  processes  are  terms  applied  to  the  working  of  this 
power. 
5 


66 


THE  BLOOD. 


THE  NUMBER   OF   TISSUES. 


1.  The  Blood. 

2.  Cellular  Tissue,  comprising 

a.  Adipose, 

b.  Serous, 

c.  Synovial, 

d.  Bursas  Mucosae. 

3.  Vascular — 

a.  Arterial, 

b.  Venous, 

c.  Lymphatic. 

4.  Nervous — 

a.  Animal, 

b.  Organic  Life. 

5.  Glandular. 


6.  Cutaneous — 

a.  External  or  Skin, 

b.  Internal  or  Mucous  mem- 

brane. 
T.  Muscular — 

a.  Animal, 

b.  Organic. 

8.  Fibrous — 

a.  Ligament, 

b.  Aponeurosis. 

9.  Cartilaginous. 

10.  Fibro-cartilaginous. 

11.  Erectile. 

12.  Osseous. 


•    Anatomists  differ  as  to  the  number  of  Tissues — Bichat 
makes  21,  Homer  18,  Dupuytran  and  Kicherand  11. 


CHAPTER  II. 

THE    BLOOD.* 

THE  Blood  being  the  fountain  for  the  growth  and  susten- 
tation  of  the  whole  body — the  source  of  supply  for  the  de- 
velopment and  preservation  of  every  part — and  the  ways  and 
tneans  for  supplying  all  the  waste  places  of  the  economy, 

*M.  Magendie,  in  his  work  on  the  Blood,  says  all  its  constituents  have  "spe- 
cial functions" — a  prominent  character  of  the  Tissues — and  so  far  may  claim 
consideration  in  common  with  the  Tissues.  But  an  additional  reason  for  pla- 
cing it  among  the  Tissues,  is  first,  that  it  is  the  source  of  all  the  Tissues, 
furnishing  the  materials  for  all  the  organs,  and  is  also  the  matrix  for  the  mature 
cell,"  and  being  thus  fundamental  to  the -whole,  seems  naturally  to  demand 
examination  first. 


THE  BLOOD.  67 

has  in  the  first  place  vast  importance,  and  in  the  second  a 
fundamental  position  in  relation  to  all  other  parts. 

With  this  view  of  the  subject,  we  have  been  in  the  habit, 
and  have  found  it  a  most  profitable  one  to  commence  our 
investigations  in  Anatomy,  by  first  making  a  brief  examin- 
ation of  this  fluid  as  containing  the  primitive  a'nd  formative 
element  of  the  whole  body. 

All  the  prominent  and  most  important  facts  in  relation 
to  the  blood,  of  which  we  only  propose  to  give  as  concise  a 
statement  as  possible,  may  be  arranged  under  four  heads: 

1st.  The  physical  properties  and  relations  of  the  blood. 
2d.  Its  chemical  properties  and  relations. 
3d.  Its  microscopic  properties  and  relations. 
4th.  Its  vital  properties  and  relations. 

When  blood  is  drawn,  we  find  it  naturally  separating  into 
two  parts — the  one  thick,  called  the  crassamentum  or  clot — 
the  other  thin  and  fluid,  the  serum. 

The  proportion  which  these  bear  to  each  other,  is  stated 
to  be  four-fifths  of  clot,  to  one-fifth  of  serum. 

The  crassamentum  is  the  portion  which  forms  the  firm 
solid  mass  by  coagulation,  and  is  colored,  from  containing 
the  red  globules. 

The  serum  is  the  yellowish,  transparent,  watery  part  in 
which  the  clot  is  seen  to  float. 

The  blood,  while  circulating  in  the  body,  consists  also  of 
two  portions — a  solid  and  fluid — the  solid  being  the  glob- 
ules, while  the  fluid  is  called  the  liquor  sanguinis,  which 
holds  both  crassamentum  and  serum  in  solution. 

The  Liquor  sanguinis,  or  plasma,  is  described  as  a  pale 
and  clear  fluid,  containing  the  corpuscles,  and  when  drawn, 
presents  as  its  striking  characteristic,  a  disposition  to  co- 
agulate. 

During  coagulation,  the  corpuscles  are  retained,  but  can 
be  separated  by  the  filter,  as  recommended  by  Muller. 

In  inflammatory  diseases  the  red  corpuscles  subside  before 
coagulation  occurs,  leaving  the  upper  portion  of  the  blood 


68  THE  BLOOD. 

a  clear  liquid.  The  liquor  sanguinis  has,  however,  the  pale 
corpuscles  mixed  with  it,  which  are  found  to  collect  at  the 
top,  and  this  clear  liquid  which  is  found  at  the  top  after  co- 
agulation, when  inflammation  has  been  present,  is  styled 
the  bujfy  coat,  and  is  found  to  separate  into  fibrin  and  serum. 

The  liquor  sanguinis  shows  under  the  microscope  numer- 
ous fine  filaments  variously  interwoven. 

The  fibrin  may  be  separated  from  the  blood  by  stirring  it 
with  a  stick  roughly  notched,  and  its  proportion  is  supposed 
not  to  exceed  two  and  one-half  parts  in  the  thousand.  Its 
quantity  is  regarded  as  greater  in  arterial  than  venous  blood. 

The  color  of  the  blood  is  the  first  physical  property  we 
notice.  This  is  a  beautiful  red  or  vermilion  in  the  arteries, 
modena  or  purple  in  the  veins,  and  still  darker  in  the  vena 
portae. 

Its  quantity  has  been  variously  estimated  by  differe'nt 
physiologists — the  extremes  being  8  pounds  for  the  lowest 
and  100  pounds  for  the  highest. 

The  calculations  of  Hoffman  and  Valentin  are  regarded  as  / 
coming  nearest  the  truth.     Hoffman  makes  the  weight  of 
the  blood  to  the  whole  body  as  1  to  5 — hence,  an  individual 
weighing  150  pounds,  has  30  pounds  of  blood  or  nearly  4 
gallons. 

Its  smell  is  faint  and  peculiar,  and  has  been  compared  to  a 
fragrant  garlic  odor. 

The  taste  is  slightly  saline  and  peculiar. 

To  the  touch  it  is  viscid.  It  is  also  coagulable,  has  a  tem- 
perature of  about  98°  or  100°  Fahrenheit,  and  a  specific 
gravity,  when  compared  with  water,  of  1.0527  to  1.0800. 

In  reference  to  the  property  of  coagulation  in  the  blood, 
M.  Magendie  remarks  that  it  is  a  "  fundamental  point  in 
the  theory  of  the  blood,  that  in  order  to  support  life  it  must 
be  coagulable/7  and  that  where  it  loses  this  property,  life 
must  cease  and  death  is  inevitable;  and  this  is  what  is 
believed  to  occur  in  all  those  destructive  epidemics,  as  the 
cholera,  plague,  and  yellow  fever,  the  blood  in  each  being 
in  a  fluid  state  and  not  capable  of  coagulation. 

A  variety  of  agents  are  found  to  destroy  this  property  in 


THE  BLOOD. 


69 


the  blood.  The  lancet  in  frequent  bleedings,  putrid  water, 
the  poison  of  the  viper,  fumes  of  charcoal,  bicarb,  sodae, 
nitre,  digitalis,  with  many  others,  have  this  agency. 

But  there  are  fortunately  other  agents  which  have  a  ten- 
dency to  promote  coagulation,  and  to  arrest  the  disposition 
to  its  destruction.  Among  these  stands  at  the  head  of  the 
list  water,  then  sulphate  of  magnesia,  nitrate  of  silver,  &c. 

This  property  of  ihe  blood  being  of  such  great  import- 
ance in  the  preservation  of  health  and  life,  we  deem  it  not 
out  of  place  here  to  give  a  brief  summary,  from  the  ex- 
periments of  M.  Magendie,  of  all  those  agents  which  he 
found  to  aid  or  promote  this  principle  of  coagulation,  and 
all  those  which  destroyed  it. 

Under  the  first  head  of  agents  promoting  coagulation, 
are  arranged: 


Water, 

Sugared  Water, 

Hydrochlorate  Sodae, 

Potassas, 

Ammonia, 

Baryta, 

Serum  of  Ascites, 

Boracic  Acid, 

Borax, 

Nitrate  of  Silver, 

Hydrosulphates  of  Potassa 
and  Ammonia 


Seltzer  Water, 
Vichy  Water, 
Seidlitz  Water, 
loduret  of  Potass, 
Tart.  Ant.  and  Potass, 
Sulphat.  Magnesia, 
Alcohol, 
Cyanuret  of  Gold, 

"  Mercury, 

Hydrochlorate  and  Mannite 
of  Morphia. 


Second  doss,  or  agents  which  destroy  coagulation. 


Sulphuric, 

Hydrochloric, 

Nitric, 

Tartaric, 

Oxalic, 

Citric, 

Acetic, 

Tannic, 

Hydrocyanic, 

Lactic, 

Soda, 


Acids. 


Potassa, 

Lime, 

Ammonia, 

Sodaa, 

Potassas, 

Ammoniae, 

PotassaB, 

Lime, 

Strychniaa,  ) 

Sulphate  Morphia, 

Nicotine. 


Carbonates. 


Nitrates. 


The  gases  and  wines  also  modify  this  property. 


70  THE  BLOOD. 

Viscidity  is  another  property  of  the  blood  equally  im- 
portant with  its  coagulation ;  for  the  same  authority  asserts 
that  the  circulation  is  due  to  this  property,  and  if  lost  or 
taken  away;  the  blood  is  arrested  in  its  course. 

He  states  the  remarkable  fact  that  if  we  attempt  to  in- 
troduce water  into  a  tube  of  extremely  small  diameter,  it 
will  not  enter,  no  matter  what  force  be  employed;  but  sim-- 
ply  add  a  certain  quantity  of  gum,  gelatine  or  any  mucila- 
ginous substance,  and  the  attempt  becomes  "immediately 
successful." 

The  blood,  however,  on  the  other  hand,  can  be  too  viscid, 
and  by  adhering  to  the  sides  of  the  vessels  mechanically 
obstruct  the  circulation. 

The  force  with  which  the  blood  presses  against  the  ar- 
teries, by  the  experiments  of  M.  Poiseuille,  is  nearly  the 
same  in  every  part  of  the  body. 

The  rapidity  of  the  blood  is  estimated  at  149.2  feet  per 
minute;  going  the  whole  round  of  the  circulation  in  about 
three  minutes;  requiring  in  this  time  about  240  beats  of 
the  heart,  each  beat  sending  forward  2  oz.  of  blood,  and  in 
one  hour  20  times  the  whole  weight  of  blood  in  the  body. 

There  are  other  physical  properties  of  the  blood,  as  elas- 
ticity, density,  cohesion,  &c.,  all  of  which  modify  its  char- 
acter, and  through  it,  to  a  greater  or  less  extent,  the  differ- 
ent organs. 

Now  all  the  properties  just  enumerated  owe  their  exist- 
ence and  value  to  the  unalterable  relations  which  nature 
has  established  between  the  blood  on  the  one  hand,  and 
the  external  bodies  of  food,  atmospheric  air,  water  and 
temperature  on  the  other — which  relations,  if  we  violate, 
will  be  vindicated  by  a  proportionate  alteration  or  destruc- 
tion of  the  physical  properties  of  the  blood,  and  a  conse- 
quent proportionate  impairment  of  the  health  of  the  body. 

The  chemical  properties  of  the  blood  are  thus  given  by 
M.  Lecanu,  whose  analysis  is  regarded  as  among  the  most 
.accurate.  He  makes  25  distinct  substances,  to  wit: 


MICROSCOPIC  EXAMINATION  OP  THE  BLOOD. 

Free  Oxygen,          Nitrogen,  Carbonic  Acid, 

Extractive,  PhosphurettedFat,  Cholesterin, 

Seroline,  Free  Oxalic  Acid, 

Margaric  Acid,         Carbonate  Sodae,      Albumen, 
Hydrochlor.  Potass,  Carbonate  Lime,      Water, 


Hydrochlor.  Sodae,    Carbonate  Magnes.  Fibrin, 
Hydrochlor.  Am'a,  Lactate  Sodas,          Haematosin, 
Sulphate  Potass,      Fatty  Acid  Salt,      Globules, 
Yellow  Col.  Matter. 


>  Clot 


Of  these  substances  the  serum  contains  the  water,  albu- 
men and  salts,  the  analysis  of  which  by  the  same  chemist 
is  in  1000  parts:  Water,  906;  Albumen,  *78;  Animal  Matter, 
soluble  in  Water  and  Alcohol,  1.69;  Albumen,  combined 
with  Soda,  2.10;  Crystallizable  Fatty  Matter,  1.20;  Oily 
Matter,  1;  Hydrochlorate  Soda  and  Potassa,  6;  Sub.  Carb., 
Phosphat.  Sodae  and  Sulphat.  Potassae,  2.10;  Phosphate  of 
Lime,  Magnesia,  2 ;  Iron,  Sub.  Carb.  Lime,  2 ;  Magnesia, 
0.91;  loss,  1. 

The  Crassamentum  contains  the  fibrin  and  coloring  mat- 
ter. Fibrin,  known  by  the  names  of  coagulable  lymph  and 
fibre  of  the  blood,  is  the  basis  of  muscle,  and,  according  to 
Berzelius,  in  100  parts,  has  Carbon,  53.360;  Oxygen,  19.666; 
Hydrogen,  7.021;  Nitrogen,  19.934.  The  coloring  matter 
contains  iron,  which  is  found  in  the  red  globules. 

MICROSCOPIC  EXAMINATION  OF  THE    BLOOD. 

FIG.  2.  Under  the  microscope,  nu- 

merous little  red  particles, 
termed  globules,  or  corpus- 
cula,  are  observed. 

The  form  of  the  globules 
varies  in  different  animals; 
in  man  and  all  the  mammalia 
it  is  circular  and  flattened, 

with  a  cup-like  depression  on  both  surfaces,  while  in  birds, 

reptiles  and  fishes  the  form  is  elliptical. 

FIGURE  2.  b  represents  the  blood  corpuscle  as  seen  within  the  focus  of  the 
microscope ;  a  shows  it  when  beyond  the  focus.  Magnified  400  diameters. 


72  MICROSCOPIC  EXAMINATION  OF  THE  BLOOD. 

The  size  varies  equally  with  the  form.  In  amphibia  they 
are  regarded  as  the  largest;  in  birds  and  fishes  next  in 
size,  and  in  mammalia  smallest.  The  human  globules  are 
about  one-fourth  the  size  of  those  of  the  frog.  They  are 
larger  in  the  embryo  than  the  adult,  and  are  made  to 
measure  from  the  1-5000  to  the  1-3000  of  an  inch,  though 
the  size  often  varies.  The  globules  or  corpuscles  of  the 
frog  show,  under  the  microscope,  that  their  structure  con- 
sists of  a  membranous  envelope — thin,  transparent  and 
vesicular — enclosing  a  nucleus,  seemingly  solid,  and  having 
the  colored  matter  surrounding  this  nucleus  and  placed 
between  it  and  the  envelope.  The  nucleus  is  regarded  as 
about  one-third  of  the  length  of  the  corpuscle.  The  envel- 
ope is  found  to  be  highly  elastic,  and  both  it  and  the  col- 
oring matter  are  considered  to  be  quite  soft  and  yielding  in 
their  nature. 

The  structure  of  the  human  globule  is  believed  by  some 
to  have  a  similar  envelope,  nucleus  and  coloring  substance, 
as  in  the  frog,  though  others  consider  it  extremely  ques- 
tionable whether  the  blood  corpuscle  in  man,  or  any  of  the 
mammalia,  have  any  nucleus  at  all,  and  are  therefore  dis- 
posed to  deny  its  existence  in  these  animals.  The  nucleus 
is  generally  seen  in  the  centre  of  the  corpuscle.  Besides  the 
red  corpuscle,  there  is  another  kind  called  the  pale  or  color- 
less corpuscle.  These  are  found  to  be  fewer  in  number, 
larger,  and  to  vary  less  in  size  and  shape  than  the  red.  As 
their  name  implies,  they  are  destitute  of  color  and  specifi- 
cally lighter  than  the  red. 

The  globules  are  suspended  in  the  liquor  sanguinis,  their 
natural  fluid,  without  alteration.  Water  dissolves  the  col- 
oring matter,  leaving  the  nucleus;  acetic  acid  changes  the 
form  as  well  as  dissolves  the  coloring  matter;  and  liquor 
potassse  dissolves  both  coloring  matter  and  nucleus. 

Thus  the  blood  is  seen  to  consist  of  many  chemical  and 
microscopical  elements,  each  and  all  of  which  are  adapted 
the  one  to  the  other,  in  precise  and  definite  proportions,  to 
constitute  health ;  and  to  add  to,  abstract  from  or  alter  in 
any  way  the  natural  relation  between  any  two  or  more, 


VITAL  PROPERTIES  AND  RELATIONS  OF  THE  BLOOD. 

would  be  to  produce  disorder  and  disease,  primarily  in  the 
blood  itself,  and  secondarily  in  the  organs. 

VITAL  PROPERTIES  AND   RELATIONS  OP   THE   BLOOD. 

Dr.  John  Hunter  stands  prominent  in  demonstrating 
the  vitality  of  the  blood.  The  analogy  of  the  fresh  egg 
furnished  one  of  his  strongest  proofs,  showing  that  vitality 
can  be  connected  with  the  fluids  where  there  is  no  visible 
organization  present. 

The  fresh  egg  may  be  exposed  for  weeks  with  impunity 
to  a  temperature  that  would  certainly  putrify  the  stale 
egg.  The  hen,  whose  period  of  incubation  is  three  weeks, 
keeps  her  eggs  at  a  temperature,  it  is  said,  of  105  degrees, 
yet  when  the  chick  is  hatched  the  yolk  is  perfectly  sweet. 

This  remarkable  power  of  resistance  to  heat  in  the  fluid 
of  the  egg,  could  be  attributed  to  nothing  but  its  vitality. 
Its  power  of  resisting  cold  is  equally  great.  Mr.  Hunter 
exposed  an  egg  to  1*7°  and  15°  of  Fahrenheit,  and  found  it 
took  half  an  hour  to  freeze  it.  When  thawed  and  again 
exposed  to  a  temperature  of  25°  it  froze  in  one  half  the  time. 

A  fresh  egg,  and  one  previously  frozen  and  again  thawed, 
were  placed  in  a  cold  mixture  of  25°  Fahrenheit:  the  egg 
that  had  been  frozen  was  again  frozen  25  minutes  sooner 
than  the  fresh. 

Fresh  drawn  blood,  and  blood  that  had  been  frozen  and 
then  thawed,  by  similar  experiments,  showed  the  same  re- 
sults— all  leading  to  the  same  inference  of  the  blood's 
vitality. 

Another  proof  of  the  blood's  vitality,  is  its  preserving 
the  fluid  state  while  circulating  in  the  vessels;  for,  on  be- 
ing removed  from  the  body,  coagulation,  it  is  well  known, 
very  soon  occurs.  And  it  occurs,  not  because  the  blood  is 
at  rest  and  ceases  to  circulate,  for  experiment  shows  that 
if  it  be  kept  at  the  same  temperature;  and  have  the  same 
rapidity  in  a  dead  tube  as  in  the  living,  it  will  still  become 
solid,  proving  that  its  fluidity  in  the  body  must  be  owing 
to  vital  agency. 


74     VITAL  PROPERTIES  AND  RELATIONS  OF  THE  BLOOD. 

Coagulation  of  the  blood  itself  has  been  brought  forward 
as  a  proof  of  its  vitality;  for  from  the  experiments  of  Hunter 
and  Magendie,  neither  cold  nor  heat,  rest  nor  motion,  nor 
any  other  known  agency,  seems  to  prevent  the  blood  from 
coagulating.  This  process  is  therefore  regarded  as  vital. 

The  Automatic  motion,  observed  among  the  blood  corpus- 
cles, is  thought  to  be  further  proof  of  the  blood's  vitality. 
This  motion,  however,  by  others  is  considered  a  delusion. 

The  last  proof  we  shall  here  present  of  the  blood's  vitality, 
is  its  vivifying  influence  on  the  whole  body,  which  point 
illustrates  its  vital  relations. 

There  is  no  part  of  the  body  where  the  blood  does  not 
circulate,  and  in  which  it  is  not  distributed ;  hence  every 
portion  must  be  directly  related  with  it.  And  so  close  is 
this  relation  and  dependency,  that  if,  by  ligature,  ampu- 
tation, or  any  other  cause,  the  blood  be  prevented  from 
reaching  any  organ  or  part,  that  organ  or  part  will  inevi- 
tably die.  But  allow  the  blood  to  circulate  in  and  through 
it,  and  it  becomes  refreshed,  and  exhibits  again  all  the 
sensible  proofs  of  vitality. 

Hence  the  necessary  inference,  that  vitality  must  be  con- 
nected with  the  blood — that  this  vitality  is  conveyed  in  the 
round  of  the  circulation  to  every  portion  of  the  body — and 
further,  that  all  the  solids  themselves  owe  the  existence 
and  continuance  of  their  own  vitality  to  the  supply  of  this 
fluid. 

The  Formation  of  the  Blood  is  the  last  point  we  propose 
to  notice: 

The  Chyle  and  Lymph  are  the  great  sources  from  whence 
the  materials  for  the  formation  of  blood  are  derived. 

The  Chyle,  formed  from  our  food  and  drinks  by  the  process 
of  digestion,  and  found  in  the  upper  part  of  the  small  intes- 
tine, is  taken  from  thence  by  the  Lacteals,  and,  through  the 
thoracic  duct,  conveyed  into  the  circulation,  and  thence  on 
to  the  Lungs,  where  its  formation  into  blood  is  finally 
effected. 

Organs  are  regarded  as  the  special  instruments  or  means 
for  the  formation  of  blood  in  the  higher  order  of  animals. 


THE  CELLULAR  TISSUE. 

As,  for  instance,  the  Lungs  give  the  blood  its  color — here 
elements  are  thrown  off  and  others  received.  The  digestive 
tube,  as  already  mentioned,  performs  the  initiatory  steps 
in  its  formation — and  the  organs  of  excretion  are  so  many 
purificators  in  the  process. 

But  we  have  blood  formed  where  there  is  no  organ  or  set 
of  organs  to  account  for  it — as  in  the  egg.  All  we  see  is 
the  germinal  membrane,  which  has  the  power  of  assimila- 
ting the  fluids  of  the  egg  to  itself,  and  converting  them 
both  into  blood  and  organized  vessels. 

"This  fact,"  says  Professor  Muller,  "teaches  us  that  we 
must  not  expect  to  discover  the  process  of  the  formation  of 
the  blood  and  red  particles  in  any  special  organ  of  the 
adult."  "Indeed,"  he  continues,  "it  is  very  probable  that 
in  the  adult  the  chyle  is  converted  into  blood  under  the 
same  general  vital  conditions  which  are  in  action  in  the 
incubated  egg."  From  this  it  would  seem  that  nature  has 
not  assigned  the  formation  of  the  blood  solely  to  any  par- 
ticular part  or  organ  of  the  body.  But,  in  the  language 
of  Dr.  Stevens,  "when  more  agents  than  one  are  concerned. 
in  the  production  of  certain  effects,  we  ought  not  to  con- 
sider any  one  link  in  the  chain  as  the  sole  cause,  for  all 
the  animal  functions  act  in  a  circle,  and  are  mutually 
dependent  upon  each  other." 


CHAPTER  III. 

THE    CELLULAR    TISSUE. 

ANALYSIS. 

STRUCTURE,    EXTENT,    FORM,    QUANTITY,    CONSISTENCY,    CONTINUITY — EXTERNAL 
AND    INTERNAL    CELLULAR    TISSUE RELATIONS,    USES,    DEVELOPMENT. 

CELLULAR  Tissue  (called  also  Areolar  and  uniting  Tissue) 
consists  of  filaments  of  white,  soft  layers,  intermixed  and 
interwoven  in  different  ways,  so  as  to  form  an  arrangement 


THE  CELLULAR  TISSUE. 


of  cells — hence  the  name  Cellular — these  cells  are  of  varied 
size  and  shape,  and  all  communicate. 

The  most  beautiful  specimen  of 
this  tissue  is  seen  in  the  anterior 
mediastinum  after  throwing  back 
the  sternum.  Here 
the  cells  are  very  dis- 
tinct, though  in  other 
places  they  are  so 
compact  as  to  appear 
membranous.  The 
extent  of  the  cellular 
tissue  is  commensurate  with  that  of  the  entire  body  and  its 
various  organs.  It  is  found  beneath  the  common  integu- 
ments, as  extensive  as  the  skin  itself,  forming  a  general 
external  layer,  called  the  subcutaneous  cellular  tissue.  It 
likewise  surrounds  every  organ,  and  every  part  and  fibre 
belonging  to  each  organ.  In  a  word,  there  is  no  part 
where  it  is  not  to  be  seen;  and  it  may  very  properly  be 
termed  the  matrix  or  soil  in  which  germinate  and  expand 
all  the  other  structures. 

Bordeu,  in  consequence  of  its  peculiar  connections,  styles 
it  a  Cellular  atmosphere. 

The/orm  of  this  Tissue,  as  just  stated,  is  Cellular,  but  in 
addition  to  this  special  form,  it  has  another  and  more  varied 
one,  which  it  derives  from  its  intimate  relationship  with 
the  whole  body  and  its  different  parts,  so  that  if  this  Tis- 
sue could  be  separated  entire  from  every  part  and  organ,  it 
would  present  a  perfect  outline  of  the  whole  system.  It 
would  then  be  seen  to  form  a  series  of  moulds  or  chambers, 
each  varying  in  size,  and  adapting  itself  to  the  organ  to  be 
accommodated. 

Around  the  fasciculi  of  muscle,  it  takes  the  form  of  little 
tubes,  as  numerous  as  the  muscular  fibres  themselves — con- 
nected with  hollow  organs,  it  puts  on  the  form  of  a  mem- 

FIG.  3.  a  Arrangement  of  fibres  in  Areolar  Tissue— magnified  135  diameters. 
b  Cells  being  developed  into  Cellular  Tissue. 


THE   CELLULAR  TISSUE. 

branous  cavity — and  around  glands  and  their  granules,  it 
is  more  or  less  round. 

The  quantity  of  this  tissue  varies  according  to  its  situation 
in  the  body,  and  the  period  of  life  in  which  it  is  examined. 

In  the  cranium  and  spinal  cavity,  there  is  very  little;  on 
the  surface  of  the  head  and  face  and  in  the  orbits,  there  is 
more;  about  the  trunk,  both  externally  and  internally,  it 
is  abundant,  and  particularly  in  the  mediastinum,  within 
the  thorax,  around  the  kidneys  and  rectum,  and  within 
the  abdomen  and  pelvis.  In  the  extremities  it  is  also 
abundant,  particularly  in  the  axilla  and  groin. 

The  quantity  seems  to  be  regulated  as  a  general  rule,  ac- 
cording to  the  motion  of  the  part — the  greater  the  motion, 
the  more  of  this  tissue  is  present;  the  kidneys,  rectum  and 
some  other  parts,  it  is  true,  are  exceptions. 

The  quantity  in  infancy  is  greater  than  in  the  adult — it  is 
also  more  abundant  in  women  than  in  men — and  in  the 
lymphatic  than  in  the  bilious  temperament. 

The  consistency  equally  varies  with  the  quantity — but  the 
firmness  is  not  found  in  a  ratio  with  the  quantity — as  in  the 
mediastinum  and  around  the  kidneys,  where  it  exists  in  large 
quantities,  it  is  exceedingly  fine,  delicate,  easily  torn,  and 
having  but  a  slight  degree  of  consistence;  whereas,  in  the 
fascia  lata  of  the  thigh,  the  palmar  and  plantar  fascia  of 
the  hand  and  foot,  it  presents  an  extraordinary  firmness 
and  degree  of  strength. 

The  continuity  of  the  cellular  tissue  can  be  traced  through- 
out the  body.  The  foramina  of  the  cranium  are  the  means 
of  communication  between  the  internal  and  external  por- 
tions of  the  head  and  face — from  the  face  it  is  continued 
down  the  neck  upon  the  external  surface  of  the  chest — then 
through  the  upper  opening  in  the  thorax,  it  enters  this  cavi- 
ty, covering  its  different  viscera;  from  this  it  descends  along 
the  oesophagus  and  through  the  openings  in  the  diaphragm, 
into  the  abdomen  and  pelvis,  from  whence  it  is  traced  under 
the  crural  arch  and  foramina  of  the  pelvis,  continuous  with 
that  belonging  to  the  extremities. 

It  has  been  divided  into  the  external  and  internal  cellu- 


8  THE  CELLULAR  TISSUE. 

lar  tissue,  the  former  giving  the  general  covering  to  the 
body,  surrounding,  separating  and  connecting  its  different 
parts,  while  the  latter  enters  into  and  forms  an  essential 
part  of  their  structure. 

The  relations  of  the  cellular  tissue  are  of  two  kinds — the 
one  with  organs,  one  of  whose  surfaces  is  free,  as  the  skin, 
serous  and  mucous  structures,  and  the  other  with  organs 
where  the  attachment  is  all  around. 

The  adhesion  of  this  tissue  varies  in  different  parts.  Be- 
neath the  hairy  scalp,  it  is  with  difficulty  separated  from 
the  aponeurosis  and  muscles  below — and  along  the  middle 
line  of  the  body,  as  upon  the  nose,  the  lips,  linea-alba,  and 
spinous  processes,  it  is  considered  more  adherent  than  at 
any  other  points — while  in  the  face,  trunk  and  extremities 
it  is  quite  free  and  loose. 

The  cellular  tissue  allows,  by  its  properties  of  elasticity 
and  flexibility,  the  movements  of  the  several  parts  to  be  per- 
formed readily,  the  one  upon  the  other — which  properties 
themselves  are  preseryed  by  the  presence  of  the  serum 
within  its  substance. 

In  addition  to  its  mobility,  this  tissue  has  other  uses. 
The  mucous  membrane,  as  that  of  the  stomach,  intestines 
and  bladder,  connects  with  the  muscular  fibres  that  sur- 
round it — and  in  the  serous  membranes  it  permits  that 
expansion  and  easy  motion  we  observe  in  many  of  the 
viscera. 

The  organic  element  of  cellular  tissue,  is  mostly  gelatin. 
Its  development,  from  microscopic  observations,  commences 
with  the  nucleated  cell,  which  becomes  transformed  and 
elongated  into  fibres,  and  finally  into  a  fasciculus  of  ex- 
tremely delicate  fibres. 

It  is  readily  regenerated  when  destroyed. 


FIG.  4. 


ADISPOSE  TISSUE.  7» 

ADIPOSE   TISSUE. 

The  fat  was  formerly  supposed  to 
be  a  secretion  from  the  cellula*r  tis- 
sue, and  that  its  cells  were  the  places 
of  deposit.  The  opinion  of  Hunter 
and  Beclard,  that  there  was  a  dis- 
tinct apparatus  for  this  secretion, 
the  microscope  now  proves  to  be 
correct. 

It  reveals  the  vesicles  or  cells  (fig. 
4)  entirely  distinct  from  those  of 
the  cellular  tissue,  in  having  no  com- 
munication, and  by  retaining  the  fat 
in  their  sac-like  shape,  so  as  to  com- 
pletely prevent  its  changing  its  place,  as  is  the  case  in  the 
fluids  of  the  cellular  tissue. 

The  fat  cells  are  found  scattered  at  wide  intervals,  in  the 
cellular  tissue,  and  also  collected  in  clusters  at  different 
points  in  this  same  structure. 

Indeed  they  are  almost  commensurate  with  the  cellular 
tissue,  if  we  except  the  interior  of  the  cranium,  the  ball  of 
the  eye,  the  ear,  the  nose,  the  penis,  the  eyelids,  and  the 
substance  of  glands,  where  they  are  wanting. 

The  parietes  of  the  fat  vesicle  are  very  delicate  and  sur- 
rounded with  blood  vessels,  forming  a  net  work,  from  which 
is  secreted  the  fat  deposited  in  the  cell. 

The  fat  exhibits  striking  differences  at  different  periods 
of  life.  In  the  foetus  and  infancy,  it  is  more  liquid  and 
transparent  than  in  the  adult,  when  we  find  it  more  firm 
and  of  a  yellowish  color. 

Its  quantity,  as  regards  position,  is  just  the  reverse  in 
certain  organs  in  youth  and  adult  age. 

The  skin  of  the  infant  abounds  with  fat,  causing  the 
roundness  and  plumpness  so  constant  at  this  period — while 
observations  show  there  is  very  little  about  the  heart, 
kidneys,  omentum,  rectum,  and  other  internal  parts. 


,    FIG.  4.  Exhibits  the  cells  of  adipose  tissue— magnified  135  diameters. 


80  THE  SEROUS   TISSUE. 

In  the  adult,  on  the  contrary,  the  fat  lessens  in  quantity 
and  in  many  instances  entirely  disappears  from  beneath  the 
skin — while  it  collects  in  large  quantities  about  the  heart, 
kidneys,  omentum,  &c. 

The  uses  of  the  fat  vary  with  its  situation.  Beneath  the 
skin,  it  covers  the  projections  of  bones,  thereby  increasing 
the  rotundity  and  adding  beauty  to  the  form.  In  the  or- 
bits it  serves  as  an  elastic  cushion  for  the  eye  to  roll  upon. 
In  the  palms  of  the  hands  and  soles  of  the  feet,  it  prevents 
injury  to  the  skin  from  pressure — and  in  being  a  bad  con- 
ductor of  caloric,  it  assists  in  preserving  the  body  of  uniform 
temperature,  while  in  nutrition,  it  is  regarded  as  the  great 
store-house  of  supply,  during  the  wasting  process  of  pro- 
tracted disease. 


THE    SEROUS    TISSUE. 

ANALYSIS. 

IDENTITY  WITH   CELLULAR    TISSUE,    FORM,   DIVISIONS,    REFLECTIONS,    STRUCTURE, 

FUNCTIONS. 

The  serous  tissue  has  been  brought  under  the  same  head 
with  the  cellular,  being  regarded  by  the  highest  authorities 
as  a  -modification  of  the  same. 

The  inflation  of  the  subjacent  cellular  texture  with  air, 
reduces  the  serous  membrane  to  the  same  form — protracted 
maceration  has  the  same  effect  with  greater  certainty : 
when  the  cellular  tissue  is  inflated,  the  parietes  of  the  cell 
strongly  resemble  the  finest  parts  of  the  serous  tissue — as 
seen  in  the  arachnoid  membrane. 

There  is  a  further  identity  of  functions  and  affections — 
exhalation  and  absorption  being  performed  in  each,  and 
dropsy  passing,  it  is  said,  readily  from  the  one  to  the 
other. 

The  form  of  the  serous  tissue  is  that  of  a  shut  sack.  It 
is  divided  into — 

1st.  The  serous  tissue  proper,  as  the  peritoneum,  plura, 
tunica  arachnoids,  and  tunica,  vaginalis,  situated  in  the 
abdomen,  thorax,  cranium,  and  upon  the  testicle. 


THE  SEROUS  TISSUE.  81 

2d.  The  synovial  membranes. 

3d.  The  bursae  mucosae. 

The  form  of  the  serous  tissue  has  been  stated  to  be  that 
of  shut  sacs — this  is  true  of  all  except  the  peritoneum  of  the 
female,  which  is  open  at  the  extremity  of  the  fallopian  tubes. 
These  sacs  all  line  the  various  cavities  in  which  they  are 
found,  and  are  thence  reflected  upon  the  various  organs 
and  viscera.  These  reflections  have  different  names,  ac- 
cording to  their  situation,  uses,  attachments,  &c.,  as  the 
omentum  gastro-hepaticum  or  minus,  omentum  gastro- 
colicum  or  majus,  gastro-splenicum,  mesentery,  meso-colon, 
meso-rectum,  the  ligaments  of  the  liver,  the  broad  liga- 
ments of  the  uterus,  the  ligaments  of  the  bladder,  &c.,  all 
of  which  are  the  names  of  so  many  reflections  of  perito- 
neum, illustrating  its  position  and  connection  with  the 
stomach,  liver,  intestines  and  other  organs. 

The  serous  tissue,  with  some  few  exceptions,  forms  a 
complete  investment  to  all  the  organs  and  parietes  of  cavities 
with  which  it  is  connected ;  that  portion  surrounding  the 
walls  is  the.  parietal,  that  covering  the  several  organs  is 
the  visceral  layer.  Its  continuity  as  one  unbroken  mem- 
brane, except  the  female  peritoneum,  is  admitted  by  all 
anatomists,  and  it  is  said  to  have  been  successfully  dis- 
sected, entire  and  complete,  without  the  slightest  rupture, 
from  the  abdominal  cavity  and  its  various  organs,  by  one 
Nicholas  Massa. 

How  the  peritoneum,  pleura,  &c.,  shall  cover  the  several 
viscera,  and  yet  these  same  viscera  be  upon  the  outside  of 
its  cavity,  is  often  a  difficulty  with  the  young  beginner  in 
anatomy.  The  comparison  with  the  double  night-cap,  is 
used  as  an  easy  and  familiar  illustration.  That  part  of 
the  cap  which  covers  and  fits  close  to  the  head,  represents 
the  peritoneum  covering  the  different  organs,  while  the  por- 
tion that  floats  loose  above  the  head,  and  is  external,  repre- 
sents the  peritoneum  lining  the  interior  abdominal  walls. 
Now  it  is  plain  that  the  head,  though  covered  by  the  cap, 
is  not  in  its  proper  cavity,  but  on  the  outside.  And  so  with 
the  peritoneal  sac,  all  the  organs  are  upon  the  outside,  and 
6 


82  THE  SEROUS  TISSUE. 

obtain   a   covering  by  protruding   into   or  pushing   this 
membrane  before  them  into  its  cavity. 

The  structure  of  the  serous  tissue  consists  of  thin,  white, 
transparent  membranes,  composed,  according  to  Muller,  of 
fibres,  like  the  cellular  tissue,  collected  into  bundles,  and 
forming  a  membrane.  It  has  two  surfaces,  the  one  at- 
tached, the  other  free.  The  free  surface  is  smooth,  pol- 
ished, and  constantly  lubricated  by  an  albuminous  fluid, 
which  thus  allows  the  free  motion  of  the  several  organs 
upon  each  other;  and  the  microscope  shows  that  this  free 
surface  is  covered  by  an  epithelium,  formed  of  flattened 
scale-like  cells,  as  the  epidermis — polygonal  or  tesselated, 
and  having  each  a  nucleus  in  its  centre.  Some  of  these 
cells  are  seen  to  elongate  into  hair-like  filaments  called 
cilia,  which  are  in  constant  vibration,  and,  as  supposed, 
intended  to  prevent  stagnation  of  the  fluids  with  which 
they  are  in  contact. 

The  Synovia!  Membranes  are  simply  serous  sacs  of  smaller 
size  found  about  the  different  joints.  They  line  the  in- 
ternal surface  of  the  capsular  ligaments,  and  are  thence 
reflected  upon  the  cartilages  covering  the  articular  ends  of 
the  bones.  They  are  also  seen  under  the  annular  liga- 
ments, around  tendons  and  beneath  fasciae.  The  synovial 
fluid  differs  from  the  serous  in  being  more  viscid. 

The  Bursce  Mucosce  forms  the  third  division  of  the  serous 
system,  and  are  also  modifications  of  the  cellular  tissue. 
They  consist  of  serous  sacs,  most  generally  placed  between 
muscles  and  tendons  and  bones,  and  in  connection  with 
articular  cavities  and  ligaments.  They  secrete  a  fluid 
for  lubricating  the  parts  with  which  they  are  in  contact. 
Mr.  Hooper  enumerates  the  following:  The  head  has  4; 
the  shoulder  joint  11;  elbow  joint  4;  wrist  and  hands  15; 
hip  joint  12;  knee  joint  6;  the  foot  10 — making  62  bur- 
see  mucosse  to  the  whole  body,  besides  others  more  irregular 
in  their  distribution. 

The  functions  of  the  serous  tissue  are  those  of  secre- 
tion, exhalation,  and  absorption.  The  fluid  secreted  is 
designed  to  allow  free  and  easy  motion  among  the  several 


THE  VASCULAR  TISSUE.  83 

viscera,  between  the  tendons  and  bones,  and  at  the  several 
joints.  Morbid  accumulations  of  this  fluid  constitute  sev- 
eral varieties  of  dropsy — as  ascites  in  the  peritoneum, 
hydrothorax  in  the  pleura,  hydrocele  in  the  tunica  vaginis 
testis,  &c, 

A  variety  of  opinions  have  been  entertained  as  to  the 
uses  of  the  different  peritoneal  reflections,  particularly  the 
omentum  majus.  But  as  they  are  mostly  fanciful,  we  will 
only  mention  one,  which  seems  to  be  the  most  rational 
explanation,  and  that  is,  that  they  allow  of  the  free  ex- 
pansion of  the  organs  with  which  they  are  connected — as 
the  omentum  majus,  during  the  reception  of  food,  permits 
the  safe  enlargement  of  the  stomach,  and  the  broad  liga- 
ments, during  gestation,  that  of  the  uterus. 

The  sensibility  of  this  tissue  is  remarkably  obtuse  in  the 
healthy  state,  but  when  inflamed  causes  the  most  acute 
pain. 


CHAPTEK  HI 

THE  VASCULAR   TISSUE. 

ANALYSIS. 

OBJECT,    DEFINITION    OP     CIRCULATION,   DIVISION,    SITUATION,    FORM,    ANASTOMO- 
SES,   DISTRIBUTION,    RELATIONS,    DEVELOPMENT. 

THE  great  object  of  the  vascular  tissue  is  to  convey  the 
nutritive  fluid  to  every  part  of  the  body,  to  supply  the  ma- 
terials of  its  growth  and  renovation,  as  well  as  to  remove 
those  of  its  decomposition  and  waste.  The  performance  of 
this  duty  is  styled  circulation,  from  the  fact  that  the  blood 
beginning  at  the  heart  and  going  to  every  portion  of  the 
system,  and  then  back  again  to  the  heart,  moves  as  it  were 
in  a  circle;  hence  it  is  said  to  circulate;  and  the  function 
itself,  as  just  stated,  is  called  the  circulation. 

The  heart,  arteries  and  veins  constitute  the  parts  be- 
longing to  the  circulation  proper — the  first  being  the  cen- 


84 


THE  CAPILLARY  TISSUE. 


tral  organ  for  propelling  the  blood,  the  second  conveying 
it  to  every  part  of  the  system,  while  the  third  returns  it 
back  again  to  the  heart. 

Besides  this  general  circulation,  there  is  also  distin- 
guished the  pulmonary,  the  portal,  the  capillary  and  the 
lymphatic  circulations. 

The  vascular  tissue  belonging  to  each  of  these  circula- 
tions will  be  examined  in  the  order  of  their  development, 
which  physiology  shows  to  be — 

1.  The  Capillary. 

2.  The  Portal. 

3.  The  General. 

4.  The  Pulmonary. 

5.  The  Lymphatic,  an  appendage  to  the  blood  circulation. 

THE  CAPILLARY  TISSUE. 
FIG.  5. 


The  capillary  tissue  (from  capillus,  a  hair,)  is  situated 
between  the  arteries  and  the  veins,  at  the  termination  of 
the  one  and  the  commencement  of  the  other. 

FIG.  5  shows  the  capillaries  between  the  termination  of  the  arteries  and  the 
commencement  of  the  veins  in  a  frog's  foot.  Magnified  three  diameters,  aa 
the  veins ;  66  the  arteries. 


THE  CAPILLARY  TISSUE.  85 

The  precise  point  of  separation  is  not  determined;  hence 
this  tissue  is  viewed  as  a  system  of  vessels  belonging  neither 
to  the  arteries  nor  the  veins,  "but  one  sui-generis,  and,  ac- 
cording to  Bichat,  independent  in  its  action. 

The  microscope  reveals  the  capillary  tissue  to  consist 
of  a  multitude  of  very  minute,  hair-like  vessels,  having 
distinct  parieties,  and  assuming  the  form  of  a  net-work. 
Though  this  is  the  general  form,  there  is  found  to  be  some 
variation  from  the  different  sizes  of  the  meshes,  and  from 
their  being  elongated  or  not.  The  capillary  arrangement 
in  the  small  intestines,  according  to  Soemmering,  is  arbor- 
escent; in  the  muscles  a  bunch  of  twigs;  in  the  tongue  a 
hair  pencil;  in  the  liver  a  star;  in  the  schneiderian  mem- 
brane a  trellis-work;  in  the  choroid  plexus  of  the  brain, 
and  testicle,  a  lock  of  hair;  in  the  kidneys  glomerulate. 
The  capillaries  are  the  minutest  tubes  in  the  body,  con- 
sisting, says  Beclard,  of  thin,  soft,  transparent  walls;  and, 
according  to  Muller,  having  a  mean  diameter  of  1.3700  to 
1.1850  of  an  inch,  allowing  sufficient  space  for  the  free 
passage  of  the  blood  globules,  which  are  only  from  the 
1.5000  to  the  1.3000  of  an  inch. 

The  structure  of  the  capillaries  is  regarded  by  Schwann 
as  fibrous,  the  same  as  the  larger  vessels,  and  their  con- 
tractile power  experiments  demonstrate  to  be  far  greater. 

The  capillaries  are  not  equally  abundant  in  every  por- 
tion of  the  body.  The  quantity  is  estimated  by  injections, 
congestions  and  inflammations.  An  opinion  prevailed  that 
the  whole  body  was  made  up  of  blood-vessels,  from  the  very 
minute  injections  of  the  celebrated  Ruysch.  The  micro- 
scope, however,  shows  that  various  parts  of  the  body  are 
more  vascular  than  others,  and  that  there  are  some  en- 
tirely destitute  of  any  vessels  whatever.  The  mesentery, 
or  the  web  of  the  frog's  foot  under  the  microscope,  pre- 
sents its  most  minute  capillaries,  those  admitting  but  one 
globule,  as  separated  by  a  considerable  space,  while  in  the 
mucous  membrane,  belonging  to  the  organs  of  respiration, 
in  the  same  animal,  it  has  been  observed  to  be  impossible 
to  stick  a  very  fine  needle  without  opening  several  of  these 


86  THE  CAPILLARY  TISSUE. 

vessels.  The  skin  of  man  also  shows  that  there  is  no  point 
on  its  surface  that  can  be  pricked  without  drawing  blood. 
The  mucous  membranes  are  as  abundantly,  if  not  more  so, 
supplied  with  capillary  vessels  than  the  skin.  The  cartil- 
ages, epidermis  and  hair  are  not  penetrated  by  injection, 
and  show  no  blood-vessels  whatever.  The  ligamentous 
structure,  the  dura-mater,  periosteum,  &c.,  have  few  blood- 
vessels. 

The  question  here  arises,  if  these  parts  have  few  or  no 
blood-vessels,  how  do  they  grow  and  how  are  they  nour- 
ished? The  answer  to  this  question  led  Bichat  to  believe 
and  assert  that  there  was  another  kind  of  capillaries  be- 
sides the  sanguineous,  which  carried  the  serous  or  colorless 
portions  of  the  blood  to  the  white  structures,  and  which 
he  called  exhalants.  The  existence  of  exhalant  vessels  has 
never  been  satisfactorily  demonstrated,  though  admitted 
by  many  to  exist.  The  lymphatic  capillaries  come  under 
the  same  head,  both  of  them  being  considered  equally  ne- 
cessary for  development  and  support  to  the  white  organs, 
as  the  sanguineous  capillaries  are  to  all  other  parts. 

Various  agents  are  capable  of  acting  on  the  capillaries, 
producing  contraction  and  dilatation,  and  these  may  be 
mechanical,  chemical  or  mental. 

The  principal  functions  of  the  capillaries  are  those  of 
nutrition  and  secretion,  and  their  independent  action,  ac- 
cording to  Bichat,  that  of  carrying  on  their  own  circula- 
tion without  the  heart,  and  also  of  giving  the  impulsive 
power  to  the  veins. 

This  independent  action  in  the  capillary  system,  if  one 
part  of  the  body  can  in  any  sense  be  said  to  be  indepen- 
dent of  every  other  part,  seems  most  likely  true,  as  there 
are  some  animals  low  in  the  scale  of  being,  which  are 
entirely  without  heart  and  blood  vessels,  and  possess  no 
other  kind  of  circulation  but  the  capillary,  which  is  re- 
garded as  the  primitive  or  fundamental  circulation. 


THE  PORTAL  SYSTEM. 


87 


THE  SECOND   OR  PORTAL  SYSTEM  OR  CIRCULATION. 

The  portal  by 
some  physiologists, 
is  considered  the 
primary  circula- 
tion. 

Meckel  remarks, 
"we  are  deficient 
in  exact  observa- 
tions relatively  to 
what  parts  of  the 
vascular  system  are 
formed  first,  either 
in  man  or  in  the 
mammalia.  Never- 
theless, we  may  ad- 
mit, as  almost  cer- 
tain, that  the  veins 
appear  before  the 
arteries,  and  that 
the  first  are  those  of  the  umbilical  vesicle — for  it  is  proved 
in  birds  that  the  vitelline  veins,  and  particularly  the  om- 
phalo-mesenteric,  are  soonest  developed.  Now,  the  umbili- 
cal vesicle,  in  man,  corresponds  exactly  with  the  vitelline 
sac  of  birds." 

"As  to  the  mode  of  development  of  the  vessels,"  continues 
this  Anatomist,  "we  learn  the  following  from  what  occurs 
in  the  egg.  When  at  some  distance  from  the  embryo,  we 
see  in  the  membrane  of  the  yolk,  which  is  at  first  homoge- 
neous, certain  rounded,  circumscribed  rents,  which  are  filled 
with  a  mass  more  fluid.  These  rents  are  at  first  entirely 
separated  from  each  other,  and  appear  like  islands  in  the 

FIG.  6.  The  vena-portarum — a  inferior  mesenteric  vein.  6  The  pancreas. 
c  The  splenic  vein,  d  The  spleen.  «  Gastric  veins  uniting  with  the  splenic. 
/  Superior  mesenteric  vein,  g  Descending  portion  of  duodenum,  h  Transverse 
portion,  i  Vena  portarum.  j  Hepatic  artery,  k  Ductus  communis,  chole- 
dochus.  I  Division  of  vessels  and  duct  at  the  transverse  fissure  of  the  lever. 
m  Cystic  duct. 


88  THE  PORTAL  SYSTEM. 

rest  of  the  mass — new  lacunas  are  gradually  formed  in  the 
substance  of  the  membrane  of  the  yolk,  which  increase  the 
number  of  islands,  and  give  rise  to  a  fine  net  work  of  ves- 
sels, which  ramify  exceedingly — these  soon  contain  real 
blood,  instead  of  the  clear,  thin  fluid  which  first  filled  them. 
This  vascular  net-work  is  the  commencement  of  the  ompha- 
lo-mesenteric  vein — its  trunk  is  not  the  first  portion  formed, 
but  the  ends  of  the  vessel  appear  soonest,  these  gradually 
unite  into  branches  and  finally  produce  the  trunk.  When 
the  omphalo-mesenteric  vein  is  thus  once  formed,  the  rest  of 
the  vascular  system  produces  itself  as  follows: 

"The  vein  bends  from  below  upwards,  and  dilates  on  the 
anterior  face  of  the  body  of  the  foetus  to  form  the  heart. 
From  this  the  trunk  of  the  arteries  of  the  body  arises, 
which  carries  the  blood  to  the  organs,  and  after  this  we 
see  the  accompanying  veins.  The  vessel  into  which  the 
omphalo-mesenteric  vein  opens,  or  to  speak  more  exactly, 
into  which  it  is  changed,  is  the  vena  portae.  This,  which 
at  a  later  epoch  finds  itself  simply  enclosed  in  the  general 
system  of  the  veins  of  the  body,  constitutes  at  present  the 
principal  trunk,  and  at  its  upper  part  produces  the  heart." 

The  portal  system,  in  connection  with  the  general  and 
pulmonary,  have  each  a  common  form,  which  is  compared 
to  a  tree  consisting  of  a  trunk,  branches,  twigs,  and  ramus- 
cules.  The  portal,  situated  entirely  within  the  abdominal 
cavity,  has  its  trunk  about  three  inches  in  length,  lying 
between  the  duodenum  and  the  liver.  Its  roots  are  the 
numerous  capillaries  arising  from  the  small  and  large  intes- 
tines, the  stomach,  pancreas,  and  spleen,  while  the  almost 
endless  divisions  and  subdivisions  in  the  liver,  are  the 
different  branches  and  twigs  of  the  tree.  The  liver  is 
viewed  as  the  centre  of  this  circulation. 

The  structure  of  the  portal  vessels  consists  of  three  mem- 
branes, an  external,  middle,  and  internal.  The  first  is  a  con- 
densed cellular  tissue,  not  so  strong  as  in  the  arteries.  The 
second  is  fibrous  and  contractile,  and  by  some  considered 
muscular,  having  its  fibres  running  longitudinally;  while 
the  third  is  a  delicate  serous  membrane,  having  a  smooth 


THE  GENERAL  CIRCULATION. 


89 


polish,  and,  according  to  Henle,  an  epithelium  composed 
of  vesicles  and  scales,  analogous  to  those  of  serous  and 
mucous  membranes. 

The  portal  vessels  are  veins,  but  differ  from  other  veins 
in  not  having  any  valves.  They  are  endowed  with  the 
properties  of  contractility,  extensibility,  and  elasticity. 

Their  function  is  to  convey  venous  blood,  of  the  darkest 
kind,  from  the  abdominal  digestive  organs,  except  the  liver, 
to  this  gland,  where  the  bile  is  separated  from  it.  The 
ductus  venosus  is  the  connecting  link  between  the  portal 
and  the  next  or  general  circulation. 


THE  THIRD   OR  GENERAL  CIRCULATION. 

The  general  circulation  is  styled  the  true, 
or  Circulation  Proper. 

It  commences  in  the  left  ventricle  of  the 
heart  by  the  aorta,  extends  and  ramifies 
through  every  part  of  the  body,  and  then 
returns,  by  the  vena  cava,  back  again  to  the 
heart  upon  its  right  side,  thus  completing 
the  circle.  From  this  mode  of  distribution, 
we  have  the/orm  of  two  trees — one  the  aorta, 
the  other  the  vena  cava — the  former  carrying 
the  blood  from  the  centre  to  the  circumfer- 
ence, the  latter  bringing  it  back  changed, 
from  the  circumference  to  the  centre.  The 
heart  is  the  centre. 

The  heart,  arteries  and  veins,  then,  com- 
prise the  three  natural  divisions  of  the  gen- 
eral circulation. 
M.  Bichat  makes  two  great  divisions  of  this  circulation. 

1st.  The  vascular  system  of  red  blood. 
2d.  The  vascular  system  of  black  blood. 

The  first  division  commencing  in  the  lungs,  with  the  red 

FIG.  7  represents  the  blood  moving  in  a  circle.  1,  1,  Superior  and  Inferior 
Cava.  2,  Right  Auricle.  3,  Left  Ventricle.  4,  4,  Aorta  and  common  Carotid 
Artery. 


90  THE  GENERAL  CIRCULATION. 

blood,  by  the  pulmonary  veins,  proceeding  from  thence  to 
the  left  side  of  the  heart,  thence  by  the  aorta,  to  every  part 
of  the  body.  The  second  division  beginning  with  the  black 
blood,  in  the  extremities  and  circumference  of  the  body, 
and  proceeding  thence  to  the  lungs,  its  place  of  termination. 

It  will  be  seen  that  this  mode  of  division  includes  an- 
other and  distinct  circulation  in  the  lungs,  to  be  noticed  in 
another  place. 

The  direction  of  the  vessels  belonging  to  the  vascular 
system,  with  some  exceptions,  is  generally  straight,  and 
proceeds  in  right  lines. 

All  its  different  divisions  have  free  communication,  the 
one  with  the  other,  as  the  capillary,  portal,  general,  and 
pulmonary.  So  likewise  with  the  several  parts  composing 
each  division.  This  mode  of  connection  is  called  Anasto- 
mosis, (from  cwa,  through,  and  $<yia,  mouth,)  where  the  ves- 
sels open  like  mouths,  and  run  into  each  other.  By  means 
of  injections,  the  arteries  are  often  traced  into  the  veins — 
the  lymphatics  also;  thus  demonstrating  the  free  inter- 
course between  the  arterial,  venous,  and  lymphatic  systems. 

J.  F.  Meckel  points  out  three  different  forms  of  anasto- 
mosis in  the  arteries: 

1st.  Where  two  arteries  run  into  each  other  and  form  an 
arch,  the  place  of  union  not  being  known.  This  is  the  most 
common  form,  and  is  always  found  at  the  different  articu- 
lations, and  among  the  branches  of  the  mesenteric  arteries 
in  the  abdomen.  A  most  striking  example  of  this  form  is 
the  beautiful  curve  formed  by  the  union  of  two  branches  of 
the  superior  and  inferior  mesenteric  arteries,  called  the 
great  meso-colic  arch,  and  a  hundred  similar  arcades  can 
be  seen  in  the  intestinal  arteries. 

The  2d  form  of  anastomosis,  is  where  two  vessels  unite 
by  a  small  transverse  branch,  as  in  the  anterior  and  poste- 
rior cerebral  arteries  forming  the  circle  of  Willis,  and  in 
the  pulmonary  artery  and  aorta  joined  by  the  ductus  arte- 
riosus. 

The  3d  form  is  where  two  vessels  come  together  at  an 
acute  angle,  to  form  one  common  trunk,  as  we  see  at  the 


THE  GENERAL  CIRCULATION.  91 

base  of  the  brain,  where  the  two  vertebrals  unite  to  form 
the  basilar  artery. 

The  utility  of  this  arrangement,  by  anastomosis,  between 
the  different  divisions  of  the  vascular  system  and  the  differ- 
ent parts  of  each  division,  is  strikingly  seen  in  the  safety 
it  confers,  in  the  numerous  accidents  and  operations  to 
which  the  human  frame  is  daily  subject.  As,  for  instance, 
when  the  main  vessel  leading  to  either  extremity,  as  the 
femoral  or  axillary  artery,  shall  either  by  accident,  disease, 
or  an  operation,  be  divided  or  become  obliterated,  the  limb 
would  necessarily  die,  were  it  not  for  this  wise  provision  of 
nature,  in  making  the  branches  which  go  off  from  above 
and  below  the  point  of  the  injured  vessel,  come  together, 
and  thus  carry  on  the  circulation. 

The  structure  of  the  arteries,  as  of  the  vena  portae,  con- 
sists of  three  membranes  or  coats,  an  external,  middle,  and 
internal.  The  external  is  condensed  cellular  tissue,  very 
strong  and  resisting,  composed  of  filaments  closely  bound 
together,  never  containing  any  fat,  and  connected  with  the 
surrounding  parts.  The  middle  coat,  called  also  the  mus- 
cular, is  regarded  as  the  proper  arterial  tunic.  Its  fibres 
are  yellowish,  brittle,  elastic,  and  contractile.  They  sur- 
round the  artery  in  a  circular  manner,  though  not  forming 
complete  rings,  and  are  considered  by  many  as  essentially 
muscular  in  their  character.  The  microscope  divides  this 
middle  coat  into  three  laminas,  an  outer,  yellow,  thin,  elas- 
tic— a  middle  of  circular  muscular  fibres,  and  an  inner  of 
muscular,  but  longitudinal  fibres;  hence  this  peculiar  com- 
bination of  structure  and  properties  in  this  middle  coat 
explains  how  it  is  that  when  an  artery  is  dilated,  it  returns 
by  its  elasticity  to  its  former  natural  state — and  how,  from 
its  muscularity,  it  can  be  so  contracted  as  to  entirely  de- 
stroy its  diameter  and  arrest  the  circulation.  The  experi- 
ments of  Mr.  Hunter,  as  well  as  the  daily  operations  of  the 
surgeon,  conclusively  establish  the  power  of  contraction  in 
the  arteries. 

A  circular  section  made  in  the  aorta  of  a  horse  bled  to 
death,  measured  at  first  five  inches  and  a  half,  on  being 


92  THE  GENERAL  CIRCULATION. 

stretched  it  reached  to  ten  inches  and  a  half,  and  when  let 
alone  it  contracted  to  six  inches,  when  it  became  stationary; 
the  difference  between  six  and  ten  and  a  half  inches,  is 
the  measure  of  its  elastic  force,  while  half  an  inch  is  due 
to  muscular  contraction. 

Mr.  Arnott  makes  the  following  statement,  proving  the 
contractility  of  the  arteries.  1.  A  small  living  artery  cut 
across,  soon  contracts  so  as  to  close  its  canal  and  arrest 
hemorrhage;  2.  While  an  animal  is  bleeding  to  death,  the 
arteries,  accommodating  themselves  to  the  decreasing  quan- 
tity of  blood,  contract  far  beyond  the  degree  to  which  their 
simple  elasticity  would  carry  them.  3.  The  artery  of  a  living 
animal,  if  exposed  by  dissection  to  the  air,  sometimes  will 
contract  in  a  few  minutes  to  a  great  degree,  and  in  such  a 
case  only  a  single  fibre  of  the  artery  may  be  affected, 
narrowing  the  channel  like  a  thread  tied  round  it.  4. 
When  a  living  artery  is  tied,  the  part  between  the  ligature 
and  the  nearest  branch  on  the  side  of  the  heart,  gradually 
contracts  and  becomes  at  last  a  solid  and  impervious  cord. 
The  property  of  contractility  in  the  arteries  is  admitted 
by  all,  but  that  it  is  due  to  muscular  structure  is  the  point 
in  dispute.  One  point  of  distinction,  as  mentioned  between 
the  contraction  of  arteries  and  that  of  muscle,  is  that  the 
former  cannot  be  excited  under  the  strongest  electric  and 
galvanic  stimuli,  while  the  muscles  can. 

Elasticity  has  been  stated  to  be  another  property  of  the 
middle  coat,  by  which,  if  the  artery  be  contracted  too  much, 
it  will  dilate,  and  if  dilated  too  much  it  will  again  return 
to  its  natural  size — arid  upon  this  property,  combined  with 
the  muscular  contractions  of  the  heart,  depends  the  jetting 
of  the  blood  observed  in  the  arteries. 

The  internal  coat  of  an  artery  is  smooth,  resembling  se- 
rous membrane,  and  a  continuation  of  that  lining  the  cavity 
of  the  heart,  which  by  its  duplication  forms  the  valve  found 
at  the  mouth  of  the  aorta  and  pulmonary  artery.  This 
coat  is  connected  to  the  middle  by  fine  cellular  tissue,  and 
in  advanced  age  is  often  subject  to  ossification  or  calcareous 
concretion. 


THE  GENERAL  CIECULATION.  93 

The  arteries,  in  addition  to  their  three  coats,  are  supplied 
with  nutrient  vessels,  vasa  vasorum,  as  well  as  nerves  from 
the  neighboring  parts.  They  are  also  surrounded  by  a  cel- 
lular covering  called  the  sheath  of  the  artery. 

The  veins  consist  of  the  same  number  of  coats  as  the  ar- 
teries, though  much  more  delicate  and  weak  in  their  struc- 
ture, and  readily  collapse  when  empty  or  divided.  The 
middle  coat  is  decidedly  muscular  at  the  entrance  of  the 
larger  veins  into  the  heart,  and  the  difference  between  this 
coat  and  that  of  the  arteries  is,  that  while  the  fibres  are 
chiefly  circular  in  the  arteries,  they  are  mainly  longitudinal 
in  the  veins,  which  distinction  in  the  arrangement  of  the 
muscular  fibres  of  these  two  kinds  of  vessels,  has  been  con- 
sidered a  fundamental  and  essential  point  in  the  physiology 
of  circulation. 

The  inner  coat  of  veins  is  also  serous,  and  continuous 
with  that  lining  the  cavity  of  the  right  heart.  Its  great 
peculiarity  is  in  having  valves — formed  by  its  duplication — 
whose  free  edge  looks  towards  the  heart;  they  consequently 
favor  the  onward  circulation  of  the  blood,  while  they  as 
effectually  hinder  its  retrograding. 

Each  valve  has  a  semi-circular  shape,  is  connected  by  its 
convex  edge  to  the  interior  surface  of  the  vein,  which,  being 
dilated  at  this  point,  presents  a  knotted  appearance.  These 
valves  are  most  numerous  in  the  extremities,  and  more  abun- 
dant in  the  superficial  than  the  deep-seated  veins.  They 
exist  generally  in  pairs — three  have  been  found  together, 
and  sometimes  there  is  only  a  single  one,  as  at  the 
mouths  of  the  coronary  vein,  vena  azygos,  and  vena-cava 
ascendens.  They  are  absent  in  the  large  trunks,  as  the 
venaB  cavse,  venaa  innominatae,  internal  jugulars,  iliacs, 
portal  veins,  and  the  sinuses  of  the  brain. 

The  veins  have  their  vasa  vasorum,  like  the  arteries. 
They  also  possess  the  properties  of  contraction  and  expan- 
sion, and  are,  in  some  measure,  elastic. 


THE  ARTERIAL  TREE. 


DISTRIBUTION  OF  THE  ARTERIAL  TREE. — (FlG.  8.) 

We  only  purpose,  in  this  place,  giving  a  general  outline 
of  the  arterial  tree,  or  a  rapid  summary  of  its  primary 
branches,  reserving  the  detail  for  a  more  appropriate  place. 

B.  Ascending  Aorta — its  branches, 

1.  The  right  Coronary  Artery. 

2.  The  left  Coronary  Artery. 

C.  Arteria  Innominata. 

DD.  Subclavian  Artery — branches, 

1.  The  Vertebral  Artery. 

2.  Internal  Mammary. 

3.  Inferior  Thyroid.  J 

4.  Cervicalis  Ascendens. 

5.  Transversalis  Colli. 

6.  Transversalis  Humeri. 

7.  First  and  second  Intercostals. 

8.  Supra  Scapularis. 

EE.  Axillary  Artery — branches, 

1.  Superior  Thoracic. 

2.  Thoracica  Longa. 

3.  Thoracica  Acromialis. 

4.  Subscapularis. 

5.  Circumflexa  Posterior. 

6.  Circumflexa  Anterior. 

FF.  Brachial  Artery— branches, 

1.  Profunda  Superior. 

2.  Anastomotica  Major. 
G.  Radial  Artery — branches, 

1.  Recurrens  Radialis  Anterior. 

2.  Superficial  Vote. 

3.  Arcus  Profundus,  h.  Arteria  Dor- 

salis  Pollicis. 
H.  Ulnar  Artery — branches, 

1.  Recurrens  Ulnaris  Anterior. 

2.  Recurrens  Ulnaris  Posterior. 

3.  Arteria  Dorsalis. 

4.  Arcus  Superficialis. 

5.  Digital  branches — a,  b,  c,  d,  e,  f. 
I.  Interosseous  Artery — branches, 

1.  Interossea  Superior  Perforans. 

2.  2d  Interossea,  from  the  right  Ra- 

dial Artery. 

K.  Com.  Carotid  Artery — divided  into 
L.  External  Carotid — branches, 

1.  Superior  Thyroid. 

2.  Lingual. 

3.  Facial. 

4.  Occipital. 

5.  Posterior  Auricular. 

6.  Internal  Maxillary. 

7.  Transverse  Facial. 

8.  Temporal. 

M.  Internal  Carotid— 2d  division  of 
common  Carotid — branches, 

1.  Anterior  Cerebral. 

2.  Middle  Cerebral,  Arteria  Media 

Cerebri. 

3.  Arteria  Communicans. 


N.  Vertebral  Artery — branches, 
Anterior  and  Posterior  Cerebellar 

Arteries. 
O.  Basilar  Artery — branches, 

1.  Arteria  Communicans. 

2.  Posterior  Cerebral. 

P.  Thoracic  Aorta — branches, 

1  to  10,  the  Intercostals. 
Q.  Abdominal  Aorta — branches, 

1.  Phrenic  Artery. 

2.  Coaliac — dividing  into 

3.  Gastric,  } 

4.  Hepatic,  >  Arteries. 

5.  Splenic,  ) 

6.  Superior  Mesenteric. 

7.  Renal  Capsular. 

8.  Emulgent. 

9.  Spermatic. 

10.  Inferior  Mesenteric. 

11.  Lumbar. 

12.  Middle  Sacral  Artery. 

R.  Common  Iliac  Artery,  divided  into 
S.  Internal  Iliac— branches, 

1.  Obturator. 

2.  Glutial. 

3.  Ischiatic. 

4.  Internal  Pudic. 

T.  External  Iliac— 2d  division  of  com- 
mon Iliac — branches, 

1.  Epigastric. 

2.  Circumflexa  Ilii. 

U.  Femoral  Artery— 3.  Profunda  JFe- 
moris — branches, 

1.  External  Circumflex. 

2.  Internal  Circumflex. 

3.  Perforantes. 

V.  Popliteal  Artery — branches, 

1.  Superior  External  Articular. 

2.  Superior  Internal  Articular. 

3.  Middle  Articular. 

4.  Inferior  External  Articular. 

5.  Inferior  Internal  Articular. 

X.  Anterior  Tibial  Artery— branches, 

1.  Recurrens  Tibialis. 

2.  Internal  Malleolar. 

3.  External  Malleolar. 

Y.  Posterior  Tibial  Artery— branches, 

1.  External  Plantar. 

2.  Internal  Plantar. 

a,  b,  c,  d,  e,  f,  digital  branches. 
Z.  Fibular  Artery — branches, 

1.  Anterior. 

2.  Posterior. 


FIG.  8. 


I! 

s 


rl 


P    CD 

•< 
CD    1 


ff 

S3 


96  THE  ARTERIAL  TREE. 

The  aorta,  the  great  trunk  of  this  tree,  has  its  origin  in 
the  superior  part  of  the  left  ventricle  of  the  heart;  ascends 
behind  the  pulmonary  artery  to  the  right  side,  on  a  level 
with  the  articulation  of  the  second  rib  with  its  cartilage, 
then  crosses  transversely  about  an  inch  below  the  upper 
edge  of  the  sternum  to  the  left  side,  where  it  makes  a  second 
turn  downwards  and  inwards  to  the  bodies  of  the  third  or 
fourth  dorsal  vertebra).  This  course  of  the  aorta  describes 
a  curve  called  its  arch,  consisting  of  an  ascending,  trans- 
verse, and  descending  portions.  From  the  arch  we  follow 
the  aorta  descending  through  the  thorax  upon  the  left  side 
of  the  vertebral  column  to  the  diaphragm,  beneath  the 
crura  of  which  muscle  it  passes,  and  thence  continues  to 
descend  on  the  median  line  to  the  space  between  the  fourth 
and  fifth  lumbar  vertebra,  where  it  terminates,  dividing 
into  the  common  iliacs. 

The  portion  above  the  diaphragm,  beginning  with  the 
arch,  is  called  the  thoracic  aorta — the  portion  below  is  the 
abdominal  aorta. 

The  first  branches  given  off  by  the  aorta  after  leaving  the 
heart,  are  the  coronary  arteries — two  in  number — the  right 
and  left,  which  supply  the  right  and  left  portions  of  the 
heart.  The  next  in  order  are  those  coming  off  from  the  arch, 
which  are  the  arteria  innominata,  the  left  carotid,  and  the 
left  subclavian.  These  are  large  and  important  branches, 
supplying,  with  arterial  blood,  the  head,  neck,  and  superior 
extremities.  The  arteria  innominata,  after  proceeding 
about  an  inch  and  a  quarter,  divides  into  two  branches,  the 
right  carotid  and  the  right  subclavian.  The  former  passes 
up  the  right  side  of  the  neck  to  opposite  the  corner  of  the 
os-hyoides,  where  it  again  divides  into  the  external  and 
internal  carotid  arteries,  the  former  supplying  the  right 
side  of  the  face  and  the  right  and  posterior  parts  of  the 
head,  together  with  the  right  upper  neck,  while  the  latter 
enters  within  the  cranium  and  supplies  the  right  half  of 
the  brain. 

The  left  carotid,  arising  from  the  arch  of  the  aorta, 
pursues  a  similar  course  upwards  upon  the  left  side  of  the 


DISTRIBUTION   OF  THE  ARTERIES.  97 

neck,  has  a  similar  division  at  the  os-hyoides,  into  exter- 
nal and  internal  carotids,  supplies  with  a  like  number  of 
branches  the  left  upper  half  of  the  neck,  face,  side  and 
posterior  parts  of  the  head;  while  the  left  internal  carotid 
supplies  the  left  half  of  the  brain. 

The  whole  number  of  branches,,  of  any  magnitude,  which 
belong  to  the  carotids  upon  both  sides  of  the  neck,  are  about 
22;  16  of  this  number  going  to  the  upper  neck  and  exterior 
head,  while  the  remaining  supply  the  brain. 

The  subclavian  artery,  having  its  origin  on  the  right  side 
from  the  arteria  innominata,  and  on  the  left  from  the  arch 
of  the  aorta  proceeds  in  the  first  stage  of  its  course  to  the 
scaleni  muscles,  between  the  anterior  and  middle  of  which 
it  passes.  It  then  proceeds  between  the  clavicle  and  first 
rib  to  the  tendons  of  the  latissimus  dorsi  and  teres  major 
muscles,  over  which  it  passes,  completing  the  second  stage 
of  its  course.  We  now  follow  it  down  the  arm  along  the 
inner  edge  of  the  biceps  muscle,  upon  the  brachialis  anticus 
to  a  little  below  the  elbow  joint,  forming  its  third  and  last 
stage,  where  it  divides  into  the  radial  and  ulnar  arteries, 
which  supply  the  forearm  and  hand.  These  three  stages 
have  received  distinct  names — the  first  stage  is  called  the 
subclavian,  the  second  the  axillary,  the  third  the  humeral. 
Five  branches  belong  to  the  first,  eight  to  the  second,  and 
six  to  the  third  stage.  The  whole  number  of  primary 
branches  belonging  to  the  two  subclavian  arteries,  which 
supply  the  upper  extremities,  is  about  38. 

The  chest  and  its  organs  are  next  in  order  as  we  pro- 
ceed down  the  body  and  follow  the  course  of  the  arterial 
trunk. 

The  aorta  having  made  its  curve,  gives  off  the  bronchial 
arteries  to  the  lungs;  the  oesophageal  branches,  five  or 
six  in  number,  to  the  oesophagus;  posterior  mediastinal 
branches,  as  the  name  imports,  to  the  mediastinum;  and 
ten  intercostal  branches  to  the  intercostal  spaces  and  walls 
of  the  chest — the  two  upper  intercostal  spaces  being  sup- 
plied from  the  subclavian.  These  arteries  being  all  in 
pairs,  the  whole  number  supplying  the  chest  is  about  40, 
7 


98  DISTRIBUTION  OF  THE  ARTERIES. 

The  aorta  having  passed  the  diaphragm,  "becomes  abdorn- 
inal  and  distributes  its  branches  in  the  following  order.  1. 
The  phrenic,  two  in  number,  to  the  diaphragm.  2.  The 
cceliac,  a  single  trunk,  which  divides  into  three  branches 
that  supply  the  stomach,  liver  and  spleen,  called  the 
gastric,  hepatic  and  splenic  arteries.  3.  The  superior  mes- 
entericj  about  half  an  inch  below  the  eceliac,  sends  off  innu- 
merable branches  which  go  to  the  small  intestine,  and  the 
ascending  and  transverse  portion  of  the" large.  4.  The  emul- 
gent  arteries  come  from  the  aorta  at  right  angles,  and  go 
to  the  right  and  left  kidneys.  5.  The  spermatic  going  to 
the  testicles,  are  small  and  of  great  length.  6.  The  inferior 
mesenteric  is  a  single  trunk,  supplying  the  left  colon.  *7. 
The  lumbar  arteries,  from  three  to  five  in  number,  supply 
the  walls  of  the  abdomen.  These  are  all  the  primary 
branches  given  off  by  the  abdominal  aorta  to  its  termina- 
tion, and  are  about  19  in  number.  The  whole  number  sent 
off  by  the  arterial  trunk  from  its  commencement  to  its  ter- 
mination, counting  the  two  terminating  branches,  is  about 
66 — five  from  the  curve,  forty  from  the  thoracic,  and 
twenty-one  from  the  abdominal  aorta. 

The  aorta,  as  already  stated,  terminates  at  the  space  be- 
tween the  fourth  and  fifth  lumbar  vertebrae,  from  whence 
proceed  the  common  iliacs,  which  go  to  the  sacro-iliac  sym- 
physis,  and  there  divide  into  two  main  branches,  the  inter- 
nal and  external  iliac  arteries.  The  former  supply  the 
pelvic  cavity  and  its  viscera,  the  latter  go  to  the  inferior 
extremities. 

The  principal  branches  of  the  internal  iliac  or  hypogas- 
tric  artery  are,  1,  the  ilio  lumbar;  2,  the  lateral  sacral;  3, 
the  obturator;  4,  the  middle  haamorrhoidal ;  5,  the  uterine 
peculiar  to  females;  6,  the  vesical;  f,  the  gluteal;  8,  ischiatic, 
which  go  to  the  rectum,  bladder,  vesiculae  serninales,  pros- 
tate gland,  and  walls  of  the  pelvis,  while  the  same  branches 
supply  the  vagina,  uterus,  ovaries  and  common  parts  of  the 
female. 

The  external  iliac  artery  is  so  called  till  it  reaches  Pou- 
part's  ligament,  when  it  becomes  femoral.  It  gives  off  but 


VENOUS  CIRCULATION.  99 

two  branches  in  its  course,  and  these  at  its  termination: 
1,  the  epigastric,  and,  2,  circumflexa  ilii. 

The  femoral  artery,  commencing  at  Poupart's  ligament, 
is  to  he  found  at  a  point  half  way  between  the  anterior  supe- 
rior spinous  process  of  the  ilium,  and  the  symphysis  puhis, 
situated  behind  this  ligament  and  upon  the  common  union 
of  the  psoas  magnus,  and  iliacus  internus  muscles;  thence 
it  crosses  the  pectinalis,  adductor  brevis  and  longus,  along 
the  inner  edge  of  the  rectus,  and  behind  the  sartorius  to  the 
tendon  of  the  adductor  magnus,  which  it  perforates.  There 
it  becomes  popliteal  and  continues  such  to  the  aperture  in 
the  interosseous  ligament  of  the  leg,  where  it  divides  into 
anterior  and  posterior  tibial  arteries,  supplying  the  leg 
and  foot.  The  femoral  arteries  give  off  each  four  principal 
branches  to  the  thigh ;  the  popliteal,  five  to  the  knee-joint, 
and  the  two  terminating  branches  of  the  popliteal,  to  the 
leg  and  foot.  The  whole  number  of  primary  branches 
supplying  the  lower  extremity,  is  about  28. 

The  whole  number  to  the  body  is  132 — 66  to  the  trunk, 
and  66  to  the  extremities. 

This  is  the  most  usual  way  in  which  the  arterial  system 
is  distributed,  but  we  shall  frequently  find  varieties  in  the 
origin,  course,  size,  and  number  of  the  primary  branches. 

The  venous  tree  has  its  commencement  where  the  arte- 
rial terminates,  or  more  properly,  from  the  capillaries,  the 
connecting  link  between  the  two.  The  venous  system  con- 
sists of  two  trunks,  called  the  inferior  or  ascending,  and 
the  superior  or  descending  cava. 

These  two  trunks,  with  the  coronary  vein,  return  to  the 
heart  all  the  blood  of  the  body.  We  trace  the  primary 
branches  of  the  venous  trunks  in  a  direction  contrary  to 
the  arterial,  that  is,  from  the  circumference  to  the  heart, 
instead  of  from  the  heart  to  the  circumference. 

In  the  inferior  extremity,  commencing  in  the  foot,  we 
trace  the  venous  radicles,  forming  the  superficial  and  deep- 
seated  veins. 

The  superficial  are  the  external  and  internal  saphena, 
the  former  rising  upon  the  anterior  and  external  part  of  the 


100  VENOUS  CIRCULATION. 

dorsum  of  the  foot,  the  latter  upon 
the  internal  and  plantar  portion. 
After  free  anastomosis,  the  external 
ascends  upon  the  outer  side  of  the 
leg  and  terminates  in  the  popliteal, 
while  the  internal  runs  up  on  the 
inner  side  of  the  leg  and  thigh,  and 
ends  in  the  femoral  vein,  a  short  dis- 
tance below  Poupart's  ligament. 

The  deep-seated  veins  have  all 
the  same  course,  and  the  same' name 
with  the  arteries  they  accompany ; 
every  artery  except  the  larger  trunks 
having  two  veins  called  the  venas 
comites.  Hence  we  follow  the  veins 
attending  the  anterior  and  posterior 
tibial  arteries,  with  the  peroneal, 
ascending  the  leg  and  by  their  com- 
mon junction  at  the  posterior  part 
of  the  knee  joint,  forming  the  popli- 
teal vein.  The  popliteal  vein  takes 
the  same  course  as  the  artery,  to 
the  tendon  of  the  adductor  magnus, 
where  it  becomes  femoral.  It  now 
ascends  to  Poupart's  ligament,  along  with  the  artery,  and 
upon  its  inner  side  at  the  upper  part  of  the  thigh,  where  it 
becomes  the  external  iliac  vein,  this  unites  with  the  internal 
iliac  vein  from  the  interior  of  the  pelvis,  forming  the  com- 
mon iliac  veins  on  either  side,  which  at  the  fourth  lumbar 
vertebra  unite  together  and  constitute  the  inferior  cava,  or 

FIG.  9  represents  the  trunks  and  principal  branches  of  the  venous  system. 
1  Descending  vena  cava.  2  Left  vena  innominata.  3  Right  vena  innomina- 
ta.  4  Right  subclavian  vein.  5  Internal  jugular  vein.  6  External  jugular. 
7  Anterior  jugular.  8  Inferior  vena  cava.  9  External  iliac  vein.  10  In- 
ternal iliac.  11  Primitive  iliac.  12  Lumbar  veins.  13  Right  spermatic. 
14  Left  spermatic  vein.  15  Right  emulgent  vein.  16  Trunk  of  hepatic 
veins.  17  Vena  azygos.  18  Hemi-azygos.  19  Communicating  with  left 
renal  vein.  20  Union  of  hemi-azygos  with  vena  azygos.  21  Superior  inter- 
costal vein. 


PULMONARY  CIRCULATION.  101 

lower  trunk  of  the  venous  system.  This  trunk  ascends  the 
abdomen  on  the  right  of  the  aorta,  receiving  in  its  course 
all  the  tributary  branches,  (except  those  forming  the  vena 
portas,)  to  the  diaphragm,  through  which  it  passes  direct 
to  the  right  auricle  of  the  heart.  This  vessel  returns  all 
the  blood  of  the  inferior  half  of  the  body. 

In  the  superior  portion  of  the  body  we  commence  with 
the  sinuses  of  the  brain,  which,  emerging  at  the  base  of 
the  cranium,  become  the  internal  jugulars.  These  descend 
the  neck,  and,  with  the  external  jugulars,  unite  with  the 
subclavian  at  the  base  of  the  neck,  and  form  the  vena  in- 
nominata,  which,  with  the  vena  azygos  coming  together 
upon  the  right  side,  constitute  the  superior  cava.  This 
vessel  then  descends  to  the  right  auricle,  entering  at  its  top. 

This  brings  us  to  the  next  circulation  in  order,  the 
Pulmonary.  This  is  also  called  the  lesser  circulation,  in 
contradistinction  to  the  general,  styled  the  greater  or  sys- 
temic. 

It  occupies  a  position  intermediate  between  the  venous 
and  arterial  trunks  of  the  general  circulation,  by  ending 
the  former  and  commencing  the  latter.  The  trunk  of  this 
circulation  begins  in  the  upper  portion  of  the  right  ven- 
tricle of  the  heart,  and  after  a  short  distance  divides  into 
two  primary  branches,  which  go  to  the  lungs;  these,  in  turn, 
again  divide  and  subdivide  into  countless  numbers,  which 
distribute  themselves  in  the  form  of  a  net-work  over  the  air 
cells,  which  is  called  the  rete  malpighi.  Here  it  is  that  the 
black  blood,  brought  by  the  pulmonary  artery,  changes  its 
color  to  that  of  red.  Here  commence  the  pulmonary  veins; 
and  here  in  breathing  animals  begins  the  arterial  circula- 
tion. The  pulmonary  veins — four  in  number,  two  for  each 
lung — take  the  blood  thus  changed,  and  convey  it  to  the 
left  ventricle  of  the  heart,  where  ends  the  lesser  or  pul- 
monary, and  begins  the  greater  or  general  circulation.  The 
Structure  is  the  same  as  that  of  the  arteries  and  veins  already 
described. 

There  is  one  remarkable  peculiarity  in  this  circulation, 
deserving  notice.  It  is  this :  that  its  arteries  carry  venous 


102 


THE   HEART. 


blood,  while  its  veins  carry  arterial  blood — nothing  of  the 
kind  being  found  in  any  other  arteries  or  veins  of  the 
adult  body.  In  the  foetus,  however,  the  umbilical  vein 
carries  red  blood,  and  the  internal  iliac  arteries  black,  but 
these  after  birth  become  obliterated. 

The  Heart  is  the  centre  of 
the  general  and  pulmonary 
circulations.  It  is  situated  in 
the  middle  mediastinum,  be- 
tween the  lungs  and  behind 
the  sternum.  Its  form  is  that 
of  a  cone,  the  apex  being  at  the 
junction  of  the  fifth  rib  and 
its  cartilage  on  the  left,  the 
base  above  and  obliquely  to 
the  right.  It  is  a  hollow  mus- 
cle, having  four  cavities,  two 
auricles,  and  two  ventricles. 
The  auricles  are  above,  and 
form  the  base.  The  ventricles 
are  below,  and  compose  the 
body  and  apex.  The  heart,  after  birth,  is  duplicate,  and 
consists  of  two  hearts,  right  and  left.  (Fig.  11.) 

The  right  heart,  composed  of  the  right  auricle  and  ven- 
tricle, contains  venous  blood;  the  left,  consisting  of  the 
left  auricle  and  ventricle,  has  arterial.  The  right  heart 
receives  the  trunks  of  the  venous  tree.  The  left  gives  off 
the  trunk  of  the  arterial  tree.  It  is  enclosed  in  a  strong 
fibrous  capsule,  which  connects  it  below  with  the  dia- 
phragm, and  above  with  the  great  blood  vessels  arising 
from  its  superior  portion.  Its  interior  has  valves  to  pre- 
vent the  blood  from  retrograding.  There  are  two  sets,  one 
to  each  heart.  The  right  heart  has,  at  the  ostium  veno- 

FIG.  10  represents  an  anterior  view  of  the  heart  in  a  vertical  position. 
a  Base.  6  Body  and  right  ventricle,  c  Apex,  d  Pulmonary  artery,  e  Right 
auricle.  /  Superior  cava.  g  Anterior  coronary  artery,  h  Left  ventricle. 
i  Left  auricle,  j  Aorta,  k  Arteria  innominata.  I  Common  carotid,  nt 
Left  subclavian. 


THE  HEART. 


103 


sum,    the    tricus-  FlG> 

pid  valve.  The  left 
heart,  at  the  os- 
tium  arteriosum, 
has  the  mitral 
valve.  For  fur- 
ther description 
see  organs  of  cir- 
culation. 

The  heart,  ar- 
teries, and  veins, 
are  the  three  great 
and  fundamental 
links  in  the  hu- 
man adult  circu- 
lation, each  of 
which  is  dependent  upon  the  other,  and  to  strike  out 
either  would  destroy  the  entire  function.  Notwithstand- 
ing each  of  these  parts  has  its  own  proper  and  especial 
duty  to  perform,  in  carrying  on  the  circulation,  still,  there 
are  some  who  limit  this  action  to  one  or  more  parts,  and 
deny  the  rest  any  share  in  its  performance. 

The  heart,  for  instance,  was  supposed  by  Harvey,  the  dis- 
coverer of  the  circulation,  and  others,  to  be  the  sole  agent 
in  this  function,  and  that  it  was  accomplished  by  means 
of  its  muscular  structure.  Hence  the  various  calculations 
that  have  been  made  of  the  power  of  the  heart's  contraction. 
Borelli  estimated  it  at  180,000  pounds,  while  Reil  only 
made  it  from  5  to  8  ounces.  These  are  the  two  extremes 
— very  wide  apart  and  unsatisfactory,  the  former  be- 
ing sufficient  to  rend  the  body  in  atoms,  the  latter  too 
feeble  to  be  thought  for  a  moment  sufficient  to  drive  the 
blood  from  the  heart  to  every  part  of  the  body,  and  then 
back  again  to  the  heart.  Hence  Bichat  introduces  the  ca- 
pillaries to  supply  the  deficient  power  of  the  heart.  Dr.  Barry 

FIG.  11  represents  the  heart  double.  1,  1  Superior  and  inferior  cava. 
2  Right  auricle.  3  Right  ventricle.  4  Pulmonary  artery.  5  Branches 
from  arch  of  aorta.  6  Left  auricle.  7  Left  ventricle.  8,  8  Aorta. 


104  DEVELOPMENT   OP   THE   CIRCULATION. 

believes  the  venous  circulation  to  be  performed  entirely  un- 
der the  influence  of  the  respiration — that  during  the  expan- 
sion of  the  chest  a  vacuum  is  produced  in  the  heart,  which 
the  blood  rushes  in  to  supply — but,  unfortunately  for  this 
theory,  the  foetal  circulation  goes  on  when  there  is  no  respi- 
ration. Others,  with  more  liberality,  and  no  doubt  with 
greater  truth,  allow  each  part  of  the  vascular  tissue  its  ap- 
propriate office,  and  suppose  each  to  be  equally  essential  in 
its  place  to  perfect  regularity  and  harmony  in  this  function. 

The  Development  of  the  circulation  begins  with  the  veins,  as 
has  been  traced  in  the  Portal  system  to  the  vena  cava,  at 
the  upper  part  of  which  is  the  heart. 

"The  heart,"  says  Meckel,  "appears  at  first  like  a  half 
ring  lying  loose — the  portion  first  seen  is  the  left  ventricle, 
immediately  after,  the  aorta  shows  itself,  appearing  as  a 
considerable  dilatation.  A  little  later,  the  upper  extremity 
of  the  vein  dilates,  then  contracts  before  the  venous  trunk, 
and  thus  produces  the  auricles. 

"All  the  parts  which  are  finally  double  are  still  single 
at  this  period.  The  auricle  first  becomes  double ;  an  imper- 
fect septum  descends  from  its  circumference  and  floats  in 
its  cavity,  so  that  the  two  parts  communicate  by  a  very 
broad  opening,  the  inter  auricular  canal,  called  afterwards 
the  foramen  ovale,  and  still  later,  the  fossa  ovalis. 

"The  doubling  of  the  ventricle  does  not  take  place  in  the 
same  manner,  but  is  produced  by  the  prolongation  of  the 
primitive  portion  at  its  upper  part.  The  right  ventricle 
appears  first  as  a  small  tubercle  which  gradually  extends 
itself  towards  the  summit  of  the  heart  and  communicates 
with  the  left  ventricle.  This  communication  takes  place  at 
the  upper  part  of  the  two  ventricles,  because  at  first  the 
left  cavity  only  prolongs  itself.  Hence  the  aorta  arises 
at  first  from  both  ventricles. 

"The  pulmonary  artery  is  the  last  to  detach  itself  so  as 
to  constitute  a  distinct  trunk,  but  it  was  indicated  before 
along  the  aorta.  In  fact  the  aorta,  which  at  first  arises 
solely  from  the  heart,  divides  at  some  distance  from  this 
organ  into  two  branches  at  least,  and  as  the  aorta  is  blended 


FCETAL  CIRCULATION. 


105 


gradually  with  the  ventricle,  the  bifurcation  is  depressed 
also;  and  when  one  of  the  two  branches  separates  itself 
entirely  from  the  other,  by  completing  the  formation  of  the 
opposite  portions  of  their  circumference,  the  pulmonary 
appears,  forming  a  distinct  pJG>  12. 

trunk.  But  as  the  cavities  of 
the  heart  communicate,  the 
pulmonary  continues  not  only 
at  first,,  but  during  the  whole 
of  foetal  existence,  with  the 
aorta  of  which  it  constitutes 
the  second  root." 

The  lymphatic  circulation 
will  be  noticed  under  the  head 
of  the  glandular  tissue. 

We  will  conclude  the  vas- 
cular tissue  by  briefly  point- 
ing out  the  difference  between 
the  circulation  in  the  foetus 
and  the  adult. 

This  difference  is  seen  first 
(Fig.  12)  in  the  heart.  Here, 
in  the  foetus,  the  auricles  com- 
municate by  the  foramen  ovale, 
which  after  birth  is  closed.  At 
the  mouth  of  the  inferior  cava 
there  is  a  valve  in  the  foetus, 
which  disappears  in  the  adult. 
The  pulmonary  artery  in  the  foetus  communicates  with  the 
aorta  by  the  ductus  arteriosus,  which  in  the  adult  is  closed. 

2d.  The  internal  iliac  arteries  of  the  foetus  carry  venous 

FIG.  12  represents  the  foatal  circulation,  o  Umbilical  cord.  6  Placenta. 
e  Umbilical  vein  dividing  into  three  branches,  dd  Two  of  which  go  to  the 
Liver,  e  The  third  is  the  ductus  venous,  which  goes  to  the  inferior  cava.  fg  Por- 
tal vein,  h  Right  auricle.  £  Left  auricle,  j  Left  ventricle,  k  Arch  of 
aorta.  I  m  Show  the  return  of  blood  by  the  jugular  and  subclavian  veins,  n 
Superior  cava.  o  Right  ventricle,  p  Pulmonary  artery,  q  Ductus  arteriosus. 
r  Descending  aorta,  s  Hypogastric'or  internal  iliacs.  t  External  iliacs. 


106  FCETAL  CIRCULATION. 

blood  to  the  placenta.  These  in  the  adult  are  closed  and 
become  the  superior  ligaments  of  the  bladder. 

3d.  The  umbilical  vein,  which  carries  the  blood  from  the 
placenta  to  the  foetus,  is  in  the  adult  obliterated;  that  por- 
tion between  the  umbilicus  and  the  liver,  becoming  the 
round  ligament  of  the  liver  ;  while  the  remaining  portion 
connecting  with  the  hepatic  vein,  and  thence  with  the  vena 
cava  inferior,  is  the  closed  cord  of  the  ductus  venosus. 

4th.  The  placenta,  which,  after  birth,  is  detached  from 
the  umbilical  cord. 

The  human  placenta  is  described  as  consisting  of  two 
portions,  the  one  belonging  to  the  foetus,  the  other  to  the 
uterus  of  the  mother;  dense  tufts  of  vascular  villi  compose 
the  foetal  portion,  while  the  maternal  portion  is  formed  of 
the  decidua  of  the  uterus,  which  receives  the  foetal  villi — 
thus  formed,  it  is  the  medium  of  nourishment  to  the  foetus 
during  the  period  of  utero-gestation. 


CHAPTER  IV. 

THE   NERVOUS    TISSUE. 

ANALYSIS. 

IMPORTANCE,     DIVISIONS     ACCORDING      TO      BICHAT,      SITUATION,      EXTENT,      SYM- 
METRY,    DIVISIONS      ACCORDING     TO     DEVELOPMENT,     COMPOSITION, 
FUNCTIONS,    RELATIONS. 

THE  nervous  system,  says  M.  Cuvier,  constitutes  the  ani- 
mal, and  the  other  systems  are  provided  in  order  to  serve 
and  maintain  it.  It  is  regarded  as  presiding  over  all  the 
functions  of  the  body,  as  being  the  source  of  all  sensation 
and  motion,  as  regulating  the  temperature  and  controlling 
the  different  secretions.  The  importance  of  this  tissue 
then,  cannot  be  too  highly  estimated  as  forming  one  of  the 
fundamental  elements  entering  into  the  constitution  of  the 
several  organs.  According  to  Bichat,  it  is  divided, 

1.  Into  the  nervous  system  of  animal  life. 

2.  The  nervous  system  of  organic  life. 


THE  NERVOUS  TISSUE.  107 

The  first  division,  so  called  as  it  belongs  especially  to 
animals,  connects  them  with  the  external  world,  and  is 
hence  classed  among  the  organs  of  relation  ;  while  the 
second  division  has  its  appellation  from  belonging  to  the 
functions  of  nutrition,  which  are  common  to  the  whole  or- 
ganic world,  and  constituting  organic  or  vegetative  life. 

The  first  division  is  situated  partly  within  the  cavity  of 
the  cranium  and  vertebral  canal,  and  is  the  central  portion  of 
the  system ;  while  the  remaining  part  extends  to  the  cir- 
cumference of  the  body,  and  is  denominated  the  radiating  or 
peripheral  portion.  The  second  division  seems  to  occupy 
almost  exclusively  the  trunk,  and  extends  in  a  chain  of  gan- 
glia, the  whole  length  of  the  vertebral  column,  upon  either 
side.  The  first  division  is  symmetrical,  that  is,  consists  of 
two  equal  and  similar  parts  upon  either  side  of  the  median 
line  of  the  body ;  while  the  second  division  is  in  a  great 
measure  destitute  of  this  symmetry. 

In  giving  a  general  outline  of  the  nervous  tissue,  we  will 
adopt  that  division  which  is  most  in  accordance  with  its 
development,  thus  connecting  its  Anatomy  with  its  Physi- 
ology. The  order  will  be, 

1.  The  Nerve  and  Ganglia. 

2.  The  Spinal  Marrow. 

3.  Medulla  Oblongata. 

4.  The  Brain. 

The  nervous  system  in  animals  low  in  the  scale,  is  seen 
in  the  form  of  a  double  cord ;  a  step  higher,  upon  one 
extremity  of  this  cord  are  developed  knots  or  ganglia.  In 
the  lowest  vertebrata,  as  the  fish,  five  pairs  of  ganglia  are 
found  in  succession,  upon  the  anterior  extremity  of  this 
double  cord.  In  the  higher  fishes  and  amphibia,  these 
primitive  ganglia  have  a  different  disposition.  The  first 
two  pairs  become  fused  together,  forming  a  single  ganglion, 
or  rather  are  hid  by  a  thin  membrane,  leaving  the  three 
pairs  of  symmetrical  ganglia.  This  arrangement  is  traced 
upwards  into  the  mammalia,  where,  as  in  the  dog,  is  seen 
this  single  ganglion  constituting  the  cerebellum,  and  the 


108 


THE  NERVOUS  TISSUE. 


three  pairs,  as  before,  in  succession  ;  and  by  unveiling  this 
single  one,  the  two  primitive  pair  of  Ganglia  are  revealed, 
which  are  now  hid  by  an  additional  development.  These 
Ganglia,  at  first  disjointed,  become  connected  by  transverse 
fibres,  called  commissures. 

The  order,  then,  of  development  in  the  lower  amimals 
seems  clearly  to  be,  first,  primitive  cords,  second,  Ganglia, 
and  third,  commissures  uniting  these  Ganglia  and  associa- 
ting their  functions. 

In  the  development  of  the  nervous  system  of  man,  there 
are  also  first  seen  two  filaments  or  cords,  placed  side  by  side 
longitudinally,  and  upon  these  cords  at  the  upper  ex- 
tremity are  five  pairs  of  Ganglia.  In  an  after  period  these 
two  filaments  become  united  and  form  the  spinal  cord, 
except  at  their  superior  end,  where  they  continue  apart  in 
the  crura  cerebri.  The  first  pair  of  Ganglia  are  developed 
into  the  Cerebellum.  The  second  pair,  in  animals  the  optic 
lobes,  have  in  man  become  the  Tubercula  Quadrigemina. 
The  third  pair  form  the  Optic  Thalami,  and  the  fourth  the 
Corpora  Striata,the  basis  of  theHem- 
ispheres,  while  the  fifth,  very  large 
in  the  lower  animals,  are  small  in 
man  and  form  the  olfactory  bulbs. 
Thus  the  same  order  of  development 
in  the  nervous  tissue  is  established 
in  man  as  in  the  lower  animals :  1. 
The  primitive  fibres  or  cords.  2. 
Ganglia  upon  these  cords.  3.  Com- 
missures connecting  these  Ganglia — and  finally,  develop- 
ment from  these  Ganglia  into  the  mature  and  perfect  Brain. 

The  Nervous  Tissue  wherever  examined,  is  seen  to  be 

FIG.  13  represents  the  minute  structure  of  nerve. 

a  Loop  termination  of  nerve  fibres — one  of  the  loops  is  convoluted  and 
three  are  simple.  6  Represents  the  varicose  appearance  of  a  white  nerve 
fibre  from  the  brain,  which  is  made  so  by  pressure  or  traction,  c  A  white 
nerve  fibre  enlarged  to  exhibit  its  structure,  which  is  seen  to  be  tubular,  and 
containing  a  substance  called  neurine.  d  A  nerve  cell,  showing  its  granular 
contents,  e  Nucleus  and  nucleolus.  /  Processes  given  off  from  a  nerve  cell. 
g  Nerve  granules. 


THE  NERVOUS  TISSUE.  109 

composed  of  two  substances,  the  one  white,  the  other  gray, 
or  cineritious. 

Under  the  microscope  the  white  substance  is  found  to 
consist  of  fibres  forming  perfect  cylinders,  and  varying  in 
diameter,  having,  according  to  Solly,  an  average  diameter 
of  1-2000  to  1-4000  of  an  inch.  They  consist  of  a  trans- 
parent neurilemma,  containing  a  soft  homogeneous  sub- 
stance, which  on  pressure  assumes  the  knotted  form,  as 
seen  in  5,  figure  13.  This  white  substance  constitutes  the 
whole  of  the  nervous  trunks  and  a  large  part  of  the  central 
masses. 

Its  chemical  constitution,  by  the  analysis  of  Mr.  John, 
is  Water  73,  Albumen  9.9,  White  fatty  matter  13.9,  Bed 
fatty  matter  0.9,  Osmazome  1,  Earthy  Phosphates  1.3. 

Besides  these  tubular  fibres  of  the  white  nervous  matter, 
there  are  others  belonging  to  the  sympathetic  nerves, 
which  are  found  to  be  only  about  half  the  diameter  of 
these  fibres.  They  are  of  a  grayish  color  and  are  called 
organic  fibres. 

The  gray  portion  of  nervous  tissue,  according  to  the 
microscope,  consists  of  spherical  globules,  containing  a 
nucleus  with  nucleoli,  having  a  very  fine  filamentous  cov- 
ering and  connected  by  processes  to  surrounding  globules. 
These  globules  are  from  1-3000  to  1-1250  of  an  inch  in 
diameter.  This  gray  matter  forms  the  outer  covering  of  the 
Hemispheres  of  the  brain,  and  is  there  called  Cortical  or 
Cineritious.  It  exists  in  the  interior  of  the  spinal  cord,  and 
composes  the  centre  of  the  Ganglia. 

Its  chemical  constitution,  according  to  the  same  chemist, 
is  Water  85,  Albumen  7.5,  White  fatty  matter  1,  Eed  fatty 
matter  3.7,  Osmazome  1.4,  Earthy  Phosphates  1.2. 

The  gray  matter  is  regarded  as  the  source  of  nervous 
power,  and  its  collection  at  various  points  constitutes 
the  nervous  Ganglia,  which  are  regarded  as  so  many 
independent  centres  of  nervous  action;  while  the  white 
matter  and  its  fibres  are  considered  the  conductors  of  the 
nervous  energy. 

The  white   and  gray  matter  in  varying    proportions 


110  THE  NERVOUS  TISSUE. 

form,  the  Brain,  the  analysis  of  which,  according  to  Vau- 
quelin,  is 

Albumen, 

»•          Cerebral  fat, 

Phosphorus, 

Osmazome, 

Acids,  Salts,  Sulphur, 

Water, 

100.00 

The  Nerves. — The  primitive  fibres  already  spoken  of, 
collected  in  bundles  and  surrounded  by  a  sheath,  their 
neurilemma,  constitute  a  nerve.  Nerves  are  of  various  kinds, 
which  the  dissections  and  experiments  of  Sir  Charles  Bell 
most  clearly  demonstrate. 

He  distinguishes  nerves  of  Motion,  nerves  of  Sensation, 
and  Kespiratory  nerves.  Dr.  Hall  has  since  added,  what 
he  calls,  the  Excito-Motor  nerves. 

The  nerves,  composed  of  many  filaments,  have  their 
roots  or  origin  in  a  line  or  streak  of  nervous  matter,  as 
seen  in  the  Brain,  which  is  called  a  Tract.  When  these 
streaks  are  raised,  the  term  rod  or  column  is  applied,  as 
the  anterior  and  posterior  rods  of  the  spinal  marrow. 

These  tracts  and  columns  of  nervous  matter,  are  consid- 
ered the  sources  of  endowment  to  all  the  nerves  originating 
in  them,  and  the  different  endowments  and  peculiar  func- 
tions of  each  are  owing  to  the  fact  of  their  arising  from 
different  nervous  tracts. 

All  nerves  arising  from  the  same  tract,  have  the  same 
endowment  their  whole  length,  from  origin  to  termi- 
nation. For  example,  if  we  take  a  filament  of  a  nerve 
whose  office  is  to  convey  sensation,  that  power  will  belong 
to  it  in  all  its  course,  whether  traced  in  the  foot,  leg,  spine 
or  brain.  When  pricked  or  injured  in  any  way,  sensation, 
and  not  motion,  will  be  the  result,  and  the  perception  of 
the  impression  will  be  referred  to  that  part  of  the  skin 
where  the  remote  extremity  of  the  filament  is  distributed. 


THE   NERVES.  Ill 

But  nerves  arising  from  different  tracts  may  be  enclosed 
in  the  same  bundle,  and  this  may  consequently  have 
different  endowments.  Hence  the  distinction  into  simple 
and  compound  nerves.  Those  filaments  coming  from  the 
same  tract  are  called  Funiculi,  and  form  simple  nerves. 
Those  coming  from  different  tracts  are  called  Fasciculi, 
and  form  the  compound  nerves.  The  ninth  is  a  simple,  the 
spinal  are  compound  nerves. 

The  course  of  the  nerve  fibres  is  straight,  and  without 
branches,  from  their  origin  to  their  termination. 

A  communication  of  nerves  by  means  of  their  funiculi  and 
fasciculi,  forms  a  kind  of  net  work  called  Plexus;  the 
nerves,  however,  do  not  run  into  each  other  and  form  an 
anastomosis  after  the  manner  of  blood  vesse.ls ;  they  simply 
come  together,  enter  each  other's  sheaths,  run  side  by  side, 
but  are  not  fused  into  one. 

The  use  of  a  plexus  is  two-fold.  1st.  It  intermixes  fibres 
of  fundamentally  different  endowments,  as  the  spinal  ac- 
cessory and  par  vagum — the  former  a  motor,  the  latter  a 
nerve  of  sensation.  2d.  It  advantageously  distributes  nerves 
of  the  same  endowments,  as  in  the  Brachial  plexus,  where 
the  filaments  of  five  segments  of  the  spinal  cord  are 
mixed  together,  and  proceed  in  this  mixed  state  to  the 
several  parts  upon  which  they  are  distributed.  By  which 
arrangement  no  part  can  be  paralyzed,  till  all  the  five 
segments  or  centres  of  action  are  destroyed — while  if  each 
centre  sent  its  nerves  singly  and  alone  to  any  part,  when 
that  centre  becomes  destroyed,  the  part  upon  which  its 
nerves  are  spent  will  inevitably  suffer  paralysis. 

The  nerves  terminate  (Fig.  13)  in  loops  or  arches,  or 
more  properly  speaking,  they  have  no  free  extremity,  but 
form  circles;  those,  for  instance,  going  from  the  spinal 
marrow  and  brain  to  the  circumference  of  the  body,  which 
conduct  the  motor  power,  and  called  efferent — while  the 
afferent,  which  begin  where  the  others  stop,  are  contin- 
ued back  again  to  the  place  from  whence  they  started — 
thus  completing  the  circle,  and  conducting  to  the  central 
nervous  ganglia,  sensory  impressions. 


112 


SPINAL  MARROW. 


The 
order, 

FIG. 


origin  of  the  nerves  brings  us  to  the  part  next  in 
which  is  the 

SPINAL  MARROW. 

The  primitive  longitudinal  filaments,  al- 
ready noticed,  coming  together  and  growing, 
swell  into  the  spinal  cord. 

This  cord,  or  marrow,  occupies  the  bony 
vertebral  canal,  extending  from  the  atlas  to 
the  second  lumbar  vetebra,  where  it  termi- 
nates in  the  cauda-equina.  It  is  surrounded 
by  three  membranes — the  dura-mater,  tunica 
arachnoidea,  and  pia  mater — the  first  a  fibrous, 
the  second  a  serous,  the  third  a  vascular  mem- 
brane. 

The  spinal  marrow  presents  the  form  of 
a  cylinder  having  several  enlargements  in  its 
course,  corresponding  to  the  points  where  the 
large  plexuses  are  given  off  as  the  brachial  and 
lumbar.  It  is  divided  in  front  and  behind,  by 
two  fissures,  anterior  and  posterior ;  thus  sep- 
arating it  into  two  equal  and  lateral  halves. 
These  two  halves  are  again  divided  by  a  lateral 
line,  which  consequently  cuts  the  cord  into 
four  parts — two  anterior,  and  two  posterior. 

These  parts  receive  the  name  of  nervous 
tracts,  rods  or  columns.  Their  outer  surface  is 
white  or  medullary,  while  the  inner  is  gray  or 
cineritious. 

There  is  still  another  tract  placed  between 
the  anterior  and  posterior  columns,  called  by 

FIG.  14.  Anterior  view  of  Spinal  Marrow. 

o  Dots  showing  corpora  pyramidalia.  6  Corpora  olivaria.  c  Anterior  face 
of  spinal  marrow,  d  Anterior  roots  of  cervical  nerves,  e  Anterior  roots  of 
dorsal  nerves.  /Anterior  roots  of  lumbar  nerves,  g  Anterior  roots  of  sacral 
nerves,  h,  t,  j,  k  Anterior  and  posterior  roots  joined  to  pass  out  of  the  dura- 
mater.  I  Dura-mater  of  spinal  cord,  m,  n,  o,  p  Ganglia  on  cervical,  dorsal 
lumbar  and  sacral  nerves,  q  Cauda  equina.  r  Sub-occipital  nerve,  s  Liga- 
mentum  denticulatum. 


SPINAL  MARROW.  113 

Mr.  Bell  the  respiratory  tract,  which,  with  the  anterior, 
forms  what  is  termed  antero-lateral. 

These  different  columns  give  origin  to  different  nerves 
having  different  endowments. 

FIG.  15. 

The  anterior  give  off 
the  nerves  of  motion, 
and  the  posterior  those 
of  sensation,  the  latter 
distinguished  by  hav- 
ing a  ganglion  on  their 
root.  And  the  middle 
portion  supplies  the  respiratory  nerves.  There  is  still 
another  set  of  nerves  described  by  Mr.  M.  Hall,  as  having 
their  centre  in,  and  belonging  most  especially  to  the  spinal 
marrow,  called  the  excito-motory,  or  reflex  nerves,  having 
an  action  entirely  independent  of  volition,  and  conse- 
quently having  the  power,  as  proved  by  experiment,  of 
producing  muscular  movement  when  the  brain  is  absent. 
The  fibres,  over  which  the  brain  exerts  its  influence  in 
producing  voluntary  motion,  do  not  stop  in  the  spinal  mar- 
row, but,  according  to  Mr.  Solly,  curve  upwards  and  extend 
to  the  brain,  thus  explaining  most  satisfactorily  why  it  is 
that  apoplexy,  by  compressing  these  cerebral  fibres,  should 
produce  a  loss  of  voluntary  motion  and  sensation,  while 
those  that  are  free  and  uncompressed  in  the  spinal  cord 

FIG.  15.  Section  of  the  spinal  marrow,  with  its  membranes. 

a  Dura  mater.  6  6  Dura  mater  forming  a  sheath  for  each  of  the  roots  of  a 
spinal  nerve,  and  afterwards  a  sheath  for  the  nerve  itself,  c  c  Sheath  around 
each  of  the  roots  of  the  spinal  nerve,  by  the  arachnoid,  during  its  passage 
through  that  membrane.  The  dotted  line  represents  the  arachnoid,  d  Space 
between  two  layers  of  arachnoid,  e  Space  between  arachnoid  and  pia  mater. 
/One  of  the  dentations  of  the  ligamentum-denticulatum.  g  g  Pia  mater,  h  An- 
terior median  fissure,  i  White  commissure  connecting  the  lateral  halves  of  the 
cord,  j  Grey  commissure  connecting  the  two  semilunar  processes  of  gray  sub- 
stance, k  Posterior  median  fissure.  1 1  Antero-lateral  columns  of  spinal  cord. 
m  m  Two  lateral  columns,  n  Posterior  columns,  o  o  Posterior  median  columns. 
p  Origin  of  anterior  or  motor  root  of  spinal  nerve,  q  Origin  of  posterior  or 
sensitive  root,  r  Ganglion  on  posterior  root,  s  Spinal  nerve  separating  into 
its  two  primary  divisions,  anterior  and  posterior. 

8 


114  MEPULLA  OBLONGATA. 

should  still  remain  actively  alive  to  all  impressions,  and 
produce  a  variety  of  corresponding  motions  without  volition 
or  any  consciousness  whatever. 

A  step  higher  and  we  find  these  nervous  columns  of 
the  spinal  marrow  continued  into  or  surmounted  by  the 
Medulla  OUongata. 

FIG.  16. 


FIG.  16.     Base  of  the  brain  with  its  nerves. 

a  Anterior  fissure  between  hemispheres  of  the  Brain.  6  Posterior  fissure. 
c  Anterior  lobes  of  Cerebrum,  d  Middle  lobes,  t  Fissure  of  Sylvius.  / 
Posterior  lobes  of  Cerebrum,  g  Point  of  Infundibulum.  h  Its  body,  i 
Corpora  Albicantia.  j  Cineritious  matter,  k  Crura  Cerebri.  I  Pons  Va- 
rolii.  m  Top  of  Medulla  Oblongata.  n  Posterior  prolongation  of  Pons 
Varolii.  o  Middle  of  Cerebellum,  p  Anterior  part  of  Cerebellum,  q  Its 
Posterior  fissure,  r  Superior  part  of  Medulla  Spinalis.  s  Middle  fissure  of 
Medulla  Oblongata.  t  Corpus  Pyramidale.  tt  Corpus  Restiforme.  v  Cor- 
pus Olivare.  w  Olfactory  Nerve,  x  Its  bulb,  y  Its  external  root,  z 
Middle  root,  aa  Internal  root,  bb  Optic  nerve  beyond  Chiasm.  cc  Optic 
nerve  before  the  Chiasm.  dd  Motor  Occuli,  or  third  pair  of  nerves,  ee 
Fourth  pair  or  pathetic  nerves,  ff  Fifth  pair  or  Trigemini  nerves,  gg 
Sixth  pair  or  Motor  Externus.  hk  Facial  nerve,  ii  Seventh  pair  Qr  Audi- 
tory, including  Facial,  jj  kk  II  Eighth  pair  of  nerves— ninth  not  seen. 


MEDULLA   OBLONGATA.  115 

The  Medulla  Oblongata  is  within  the  cranium,  lying 
upon  the  cuneiform  process  of  the  occipital  bone,  has  the 
same  arrangement  of  the  white  and  gray  matter  as  the 
spinal  marrow,  and  by  Mr.  Salandier  is  regarded  as  the 
foundation  of  the  central  organs.  It  is  composed  of  six 
eminences,  the  corpora  pyramidalia,  the  corpora  olivaria, 
and  -the  corpora  restiformia — which  are  nothing  more  than 
the  enlargements  of  the  nervous  tracts  belonging  to  the 
spinal  marrow. 

The  corpora  pyramidalia  correspond  to  the  motor  tract; 
the  corpora  olivaria  to  the  respiratory,  and  the  corpora 
restiformia  to  the  sensory.  From  the  corpora  pyramidalia 
nervous  filaments  can  be  traced  through  the  pons  varolii, 
crura  cerebri,  thalami,  corpora  striata,  and  thence  ex- 
panding to  form  part  of  the  cerebrum.  Some  of  these 
filaments  decussate  low  down,  those  on  the  right  going  to 
the  left  side  of  the  brain,  and  those  on  the  left  to  the 
right — by  which  disposition,  paralysis  on  the  opposite  side 
of  the  body  from  injury  of  the  head  is  explained. 

The  corpora  olivaria  are  by  Mr.  Solly  regarded  as  chiefly 
motor,  and  fibres  can  be  traced  from  them  through  the 
pons  to  the  tubercula  quadrigemina,  or  optic  ganglia,  and 
thence  along  with  the  fibres  of  the  corpora  pyramidalia  to 
the  cerebrum,  some  also  going  to  the  cerebellum.  Hence 
the  cerebrum  is  by  Gall  and  Spurzheim,  who  take  this  as 
their  starting  point,  said  to  be  formed  or  developed  from 
the  corpora  pyamidalia  and  olivaria — while  the  remain- 
ing tract,  the  corpus  restiforme,  is  as  clearly  traced  into 
the  cerebellum. 

The  corpus  restiforme  differs  from  the  others,  according 
to  the  dissections  of  Mr.  Solly,  in  having  its  fibres  inter- 
lacing instead  of  parallel. 

Most  of  the  cranial  nerves  arise  from  the  Medulla  Ob- 
longata; and  from  this  fundamental  point  as  a  centre,  the 
primitive  filaments  have  been  traced,  radiating  to  the  cir- 
cumference of  the  cerebrum  and  the  cerebellum — these 
are  called  diverging  fibres.  Another  set  is  traced  from  the 
circumference  back  to  the  centre — these  are  the  converging 


116  THE  BRAIN. 

fibres.  The  two  sets  intersect  each  other,  having  spaces 
termed  ventricles,  while  the  converging  fibres  constitute 
the  Commissures  of  the  Brain. 

The  Brain,  (Fig.  16,)  filling  the  cavity  of  the  Cranium, 
is,  like  all  other  portions  of  nervous  tissue,  composed  of 
white  and  gray  matter,  but  differently  arranged,  the 
white  occupying  the  centre,  while  the  gray  covers  the 
surface.  We  however  find  both  kinds,  in  variable  quantity, 
interspersed  throughout  the  Brain.  The  Brain  is  divided 
into  Cerebrum  and  Cerebellum.  The  former  is  again  di- 
vided into  hemispheres,  and  these  subdivided  into  lobes. 
The  surface  of  the  Cerebrum  is  thrown  into  convolutions, 
which  are  regarded  as  the  organs  of  intelligence. 

The  relation  which  the  Brain,  Spinal  Marrow,  and  their 
nerves,  sustain  to  each  other  is  so  intimate  as  to  unite 
them  all  in  a  circle  of  communication  and  action.  The 
Brain,  forming  the  central  organ  of  perception,  receives 
the  impressions — the  Spinal  Marrow  and  nerves  of  Sen- 
sation convey  these  impressions,  while  the  nerves  of  Mo- 
tion carry  out  the  mandates  of  the  Brain  to  the  different 
muscles  of  the  body — thus  forming  a  circle  of  conduc- 
tion, perception,  and  action. 

This  tissue  has  likewise  the  closest  relation  with  all  the 
organs  and  functions  of  the  body. 

The  second  great  division  of  the  nervous  system  is  that 
of  organic  Life.  It  belongs  to  the  trunk,  is  connected  with 
the  organs  of  nutrition,  consists  of  a  great  number  of 
G-anglia,  whence  it  is  called  the  Granglionic  system.  These 
Ganglia  are  found  in  the  neck,  chest  and  abdomen,  and  send 
off  an  infinity  of  filaments,  which^  running  together  and  in- 
terlacing, constitute  the  various  plexuses,  following  and 
intimately  surrounding  the  arteries,  in  their  route  to  the 
several  organs.  This  system  is  also  styled  the  Sympathetic, 
as  it  connects  the  different  parts  of  the  body  together — 
Splanchnic,  from  its  being  so  largely  associated  with  the 
various  viscera — and,  more  recently,  Automatic,  from  being 
regarded  as  self-moving  and  the  original  source  of  nervous 
power  to  every  other  part. 


THE  GLANDULAR  TISSUE.  11T 

For  further  details  of  the  sympathetic,  turn  to  the 
nerves  of  the  Trunk,  as  connected  with  the  several  viscera, 
particularly  those  of  the  abdomen. 


CHAPTEK  V. 

*  JT 
THE  GLANDULAR  TISSUE. 

ANALYSIS. 
DEFINITION,   DIVISION,   FORM. 

GLANDS  are  organs  designed  to  separate  from  the  blood 
fluids  of  a  peculiar  kind,  some  of  which  are  concerned  in 
important  functions,  and  again  re-enter  the  system,  while 
others  are  ejected  from  the  body  as  not  only  useless,  but 
highly  dangerous  to  be  retained. 

This  definition  only  applies  to  those  glands  having  ex- 
cretory ducts,  which  in  reality  are  considered  as  the  only 
true  and  proper  glands,  the  others  being  more  properly 
called  ganglia. 

The  glands  may  be  arranged  under  two  divisions, 

1.  Those  having  excretory  ducts. 

2.  Those  without  excretory  ducts. 

Under  the  first  head  we  have  the  salivary  glands,  the 
liver,  the  pancreas,  the  kidneys,  the  testicles,  the  mammae, 
the  multitude  of  mucous  glands  scattered  throughout  the 
alimentary  tube,  and  the  equally  great  number  belong- 
ing to  the  skin.  Under  the  second  division  we  find  the 
lymphatic  glands,  the  thymus,  the  thyroid,  capsulae  renales, 
glandulee  Pacchioni,  and  the  pineal  gland. 

Structure. — The  simplest  form  of  a  gland  is  the  sac  or 
cell  follicle,  as,  for  instance,  the  mucous  follicles  which 
consist  of  a  simple  depression  of  mucous  membrane,  con- 
tracted at  its  orifice  into  a  narrow  neck.  A  second  form  is 
that  of  the  tube,  also  composed  of  a  reflection  of  the  mem- 
brane. By  the  combination  of  these  two  forms,  says  Pro- 
fessor Muller,  all  the  varied  glands  in  the  human  body,  as 
well  as  in  inferior  animals,  can  be  constructed. 


118 


THE  GLANDULAR  TISSUE. 


The  microscope  lias  been  most  industriously  employed  in 
the  examination  of  the  minute  structure  of  the  glands,  and 
to  it  are  we  indebted  for  most  of  our  knowledge  on  this 
subject. 

The  combination  of  the  two  elementary  forms  constitutes 
compound  glands,  of  which  two  varieties  are  noticed. 

1st.  Those  whose  tubes  ramify  in  an  arborescent  form. 

2d.  Where  they  do  not  branch  off,  but  preserve  the  same 
diameter  nearly  throughout  their  whole  course. 

The  mammary,  salivary  and  lachrymal  glands,  with  the 
pancreas  and  the  liver,  belong  to  the  first  division.  This 
division  presents  two  groups. 

FIG.  17. 

1.  The  tubes  branch 
off  with  some  de- 
gree of  regularity, 
the  first  branches 
sending  off  others, 
and  these  at  certain 
intervals  again  divid- 
ing, till  at  their  ter- 
minations, to  the  na- 
ked eye  they  present 
the  form  of  acini  lo- 
bules, or  granuli, 
which,  saysMuller,  are  "only  aggregates  of  cells,  seated  in 
clusters  on  the  extremities  of  the  most  minute  secreting 
canals  or  tubes,  which  cells  are  only  visible  by  the  micro- 
.scope."  These  minute  tubes  sometimes  branch  off  into 
delicate  coeca,  as  seen  in  the  lachrymal  glands  of  the 
turtle,  or  into  the  form  of  tufts  of  twigs  in  other  animals. 
In  the  second  group,  the  tubes  branch  off  irregularly 
and  do  not  terminate  in  cells,  but  in  tufts  or  twigs.  The 
liver  is  given  as  an  example,  and  though  it  contains  acini, 
they  are  nevertheless  composed  of  these  tufts  or  twigs. 

FIG.  17  represents  a  portion  of  the  Mammary  Gland,  and  arborescent 
arrangement  of  its  ducts.  66  cc  dd  ee  Lactiferous  ducts  and  orifices,  g  g 
g  g  Milk  cells.  ///  Excretory  ducts  from  the  cells  to  the  larger  lac- 
tiferous ducts. 


LYMPHATIC  GLANDS.  119 

The  tubes  of  the  second  variety,  instead  of  dividing 
like  the  branches  of  a  tree,  scarcely  ramify  at  all,  but 
proceed  on  in  their  course  with  scarcely  any  change  in  their 
diameter,  as  in  the  kidneys  and  testicles.  Here  we  find 
the  tubes  convoluted  and  of  extraordinary  length,  measuring 
in  the  testicle,  according  to  Dr.  Munroe,  5208  feet 

The  celebrated  Kuysch,  from  his  very  minute  injections, 
was  led  to  believe  that  glands  consisted  entirely  of  blood 
vessels,  which  had  a  direct  communication  with  the  excre- 
tory duct  But  more  recent  observations,  says  Muller, 
show  "  that  the  secreting  canals  in  all  glands,  form  an  in- 
dependent system  of  tubes — that  whether  they  be  convo- 
luted as  in  the  kidney  and  testes,  or  ramified  in  an  arbor- 
escent form,  as  in  the  liver  and  salivary  glands ;  whether 
they  terminate  by  twig-like  cceca,  as  in  the  liver,  or  in 
grape-like  clusters  of  cells,  as  in  the  salivary  glands,  pan- 
creas, and  mammary  gland ;  their  only  connection  with  the 
blood  vessels,  in  all  cases,  consists  in  the  latter  ramifying 
and  forming  a  capillary  net  work  on  their  walls,  and  in 
their  interstices,  'and  that  the  finest  secreting  tubes  are 
always  several  times  larger  in  diameter  than  the  minute 
ramifications  of  the  arteries  and  veins." 

The  lungs,  it  is  supposed,  furnish  the  best  type  for  the 
whole  series  of  glandular  organs. 

The  general  conclusion  to  which  the  microscope  has  led, 
in  reference  to  the  structure  of  glands,  is,  that  the  primi- 
tive cell  is  the  fundamental  and  operative  part  in  which  all 
secretion  occurs,  whether  in  the  simple  or  complex  gland, 
or  in  the  lengthened  secreting  tubes,  or  in  the  skin  or  any 
of  the  membranes  of  the  body ;  and  that  however  various 
the  form  of  the  elementary  parts,  all  the  glands,  without 
exception,  which  secrete  a  fluid,  follow  the  same  law  of 
conformation,  by  developing  themselves  from  the  simple 
follicle. 

LYMPHATIC   GLANDS. 

Under  this  head  we  will  give  a  general  description  of 
the  absorbent  system,  which  is  as  important  and  interest- 
ing as  the  sanguineous.  If  the  latter  carries  into  the 


120  LYMPHATIC  GLANDS. 

system  the  nutrient  material  for  constructing  the  body, 
the  former  conveys  out  the  same  material,  after  it  has  per- 
formed its  part  in  the  ceconomy,  and  becomes  useless;  or 
rather  carries  it  into  the  venous  blood,  to  become  repurified 
in  the  lungs,  again  to  enter  the  system. 

This  system  is  divided  into  the  lymphatic  glands  and 
the  absorbent  vessels. 

The  lymphatic  or  absorbent  glands,  called  also  conglo- 
bate, are  very  numerous  both  in  the  trunk  and  extremities, 
and  are  generally  seen  in  clusters  or  chains,  as  in  the  mesen- 
tery and  neck.  Their  color  is  reddish,  inclining  to  a  grayish 
hue,  though  the  bronchial  are  black  and  those  of  the  lesser 
omentum  sometimes  yellow.  Their  consistence  is  firm  and 
resisting.  They  are  surrounded  by  a  firm  capsule  of  cel- 
lular membrane,  which  sends  processes  within  their  sub- 
stance to  unite  the  different  parts,  as  blood  vessels  and 
nerves,  with  which  they  are  liberally  supplied.  Their  size 
varies  from  that  of  a  currant  to  that  of  an  almond.  Their 
form  is  round  or  oval,  though  some  are  irregular  and 
lobulated.  They  are  movable  in  the  healthy  state,  but 
become  firmly  fixed  by  inflammation.  Their  structure  is  not 
fully  determined,  though  they  seem  to  consist  essentially 
of  an  interlacement  of  lymphatic  vessels,  which  enter  these 
glands,  and  after  forming  a  kind  of  plexus,  leave  them. 

Those  entering  are  called  vasa  infereritia;  those  leaving, 
vasa  efferentia. 

Cells  are  spoken  of  as  lying  between  these  two  kinds  of 
vessels,  into  which  they  open,  and  containing  a  peculiar 
fluid.  The  absorbent  vessels  are  divided  into  the  lymph- 
atics and  lacteals,  so  called  from  the  color  of  the  fluid  they 
respectively  carry,  which  is  transparent  in  the  former  and 
milky  in  the  latter. 

Some  of  these  vessels  were  seen  in  the  mesentery  of  a 
goat  by  Herophilus  and  Erasistratus,  280  years  before  the 
Christian  era.  Aselius,  an  Italian  anatomist,  in  1622  re- 
discovered or  confirmed  the  original  observations  of  absorb- 
ents in  the  mesentery,  made  so  long  before  by  Herophilus 
and  Erasistratus,  and  found  that  these  vessels  took  up  the 


LYMPHATIC  GLANDS. 


121 


chyle,  but  where  they  took 
it  and  what  became  of  it  he 
did  not  know. 

Eustachius,  in  1564,  dis- 
covered in  the  horse  the 
thoracic  duct,  which  he 
called  vena  alba  thoracica, 
the  white  vein  of  the  chest, 
not  knowing  its  use.  Wes- 
lingius,  in  1649,  found 
that  the  chyle  vessels  or 
lacteals  of  Aselius,  termin- 
ated in  the  thoracic  duct. 
By  the  labors  of  Monro, 
Hunter,  with  others,  and 
especially  Mascagni,  the 
lymphatic  vessels  have  been 
demonstrated  as  extending 
to  almost  every  part  of  the 
body,  the  only  parts  in 
which  they  have  not  been 
seen  are  the  brain,  spinal 
marrow,  ball  of  the  eye,  and 
placenta.  The  lymphatics 
have  been  considered  as  an 
appendage  to  the  venous 
system.  They  resemble  the 
veins  in  having  the  same 
structure,  though  their  coats  are  more  delicate.  Like 
veins,  they  have  numerous  valves  which  give  them  a 
knotted  appearance.  Their  currents  are  in  the  same  di- 
rection, and  terminate  in  veins.  But  they  differ  from 
veins  in  passing  through  glands,  in  being  less  tortuous, 

FIG.  18  represents  the  formation  and  course  of  the  thoracic  duct. 

a  Termination  of  thoracic  duct.  6  Its  separation  into  two  ducts,  which  again 
unite,  c  Lower  end  of  duct,  d  Left  azygos  vein,  e  Right  azygos.  /  Inter- 
costal veins  entering  right  azygos.  g  h  i  j  Correspond  to  numerous  lacteals 
and  lymphatics,  which  go  to  form  the  commencement  of  the  thoracic  duct. 


122  LYMPHATIC  GLANDS. 

and  in  having  more  numerous  and  perfect  valves.  These 
valves  are  generally  semilunar,  and  arranged  in  pairs, 
though  some  are  circular  and  do  not  close  the  canal 
entirely. 

The  origin  of  the  lymphatics  is  still  involved  in  doubt, 
whether  in  the  various  tissues  they  commence  by  open 
mouths,  or  are  continuous  with  one  set  of  the  arteries,  and 
carry  the  serous  portion  of  the  blood,  or  whether  they 
begin  by  a  fine  net-work  of  vessels.  Let  their  microscopi- 
cal origin  be  what  it  may,  it  is  well  ascertained  that  the 
lymphatics  come  from  nearly  every  portion  of  the  body, 
while  the  lacteals  spring  exclusively  from  the  interior  of 
the  intestinal  tube,  and  especially  its  upper  part. 

The  former  carry  lymph,  the  worn-out  material  of  the 
body;  the  latter,  the  lacteals,  convey  chyle,  the  fresh  mate- 
rial formed  by  the  process  of  digestion.  Both  sets  of  vessels, 
after  passing  through  the  various  lymphatic  glands,  ulti- 
mately meet  and  converge  to  a  point  upon  the  second  lum- 
bar vertebras,  behind  the  aorta,  and  below  the  diaphragm, 
called  the  receptaculum  chylL 

This  receptacle  of  the  chyle  forms  the  commencement  of, 
and  is  continuous  with  the  thoracic  duct,  (Fig.  18,)  a  tube 
extending  up  the  thorax  between  the  aorta  and  vena  azygos 
to  the  fourth  dorsal  vertebras,  where  it  inclines  obliquely 
to  the  left,  behind  the  oesophagus  and  aorta,  and  inside  of 
left  subclavian  artery,  to  the  seventh  cervical  vertebra, 
from  which  it  arches  downward  and  outwards  to  the  junc- 
tion of  the  internal  jugular  and  left  subclavian  veins,  at 
which  angle  it  enters,  protected  by  a  pair  of  valves  which 
prevent  regurgitation.  This  tube  receives  the  lacteals  and 
the  lymphatics  belonging  to  the  lower  extremities,  abdo- 
men, left  half  of  the  chest,  left  side  of  the  head  and  neck, 
and  the  left  upper  extremity.  The  lymphatics  of  the  right 
side  of  the  head,  right  neck,  right  upper  extremity,  and 
right  lung,  meet,  and  enter  the  venous  system  on  the  right 
side  by  a  second  tube,  at  the  junction  of  the  right  subcla- 
vian and  internal  jugular. 

The  lymphatics  are  endowed  with  the  properties  of  con- 


THE  CUTANEOUS  TISSUE.  123 

tractility,  elasticity,  and  extensibility,  which  are  no  doubt 
employed  in  their  function  of  circulating  the  lymph,  but 
this  point  is  by  no  means  yet  satisfactorily  settled. 


CHAPTER  VI. 

T.HE    CUTANEOUS    TISSUE. 

ANALYSIS. 
IMPORTANCE,    EXTENT,    FORM,  STRUCTURE,  FUNCTIONS    AND    RELATION!. 

THIS  tissue,  especially  its  external  portion,  has  received 
the  names  of  dermoid,  tegumentary,  compound  villous,  or 
follicular  membranes.  Its  importance  may  be  estimated 
from  its  early  development,  vast  extent,  complexity  of 
structure,  variety  of  function,  diversity  of  relations,  and 
number  of  diseases. 

In  the  language  of  M.  Beclard,  this  tissue  is  the  "  most 
universally  extended  in  the  animal  kingdom;  it  is  the  first 
which  is  distinct  and  figured  in  the  embryo;  it  is  on  it 
and  by  it  the  rest  of  the  body  is  formed;  and  it  con- 
tains the  most  essential  functions,  is  often  changed  by 
disease,  is  the  part  on  which  all  foreign  substances  produce 
impressions,  and  most  therapeutic  agents  are  applied." 

The  extent  of  this  element  is  commensurate  with  the 
whole  external  and  internal  surface  of  the  body,  wherever 
exposed  to  the  contact  of  foreign  substances.  Its  form  has 
been  compared  to  two  canals,  the  one  wide  and  external, 
the  other  narrow  and  internal,  and  the  two  continuous, 
the  intervening  space  being  occupied  by  the  rest  of  the  body. 
From  this  peculiarity  of  form,  it  consists  of  two  great 
divisions. 

1st.  The  skin  and  its  appendages,  forming  the  outer  canal 
or  external  surface. 

2d.  The  mucous  membrane,  forming  the  inner  canal  or 
internal  surface. 


't 

124  SKIN  AND  ITS  APPENDAGES. 

Though  these  two  divisions  present  striking  differences 
at  first  sight,  yet  they  are  so  closely  allied  in  structure, 
being  regarded  as  essentially  the  same,  that  we  shall  ex- 
amine both  as  belonging  to  the  same  tissue. 

The  skin  can  be  traced  as  gradually  sliding  into,  and 
becoming  insensibly  lost  in  the  mucous  membrane  at  all 
the  natural  apertures,  as  the  mouth,  anus,  prepuce,  labia, 
&c.,  showing  the  continuity  of  the  two  divisions  ;  and  their 
identity  is  further  established  by  their  being  convertible  the 
one  into  the  other.  For  instance,  in  the  axillee,  nates  and 
other  parts,  where  opposing  surfaces  of  the  skin  come  in 
contact  and  are  not  kept  clean,  the  skin  will  become  moist 
and  soft,  and  present  all  the  appearances  of  mucous  mem- 
brane. On  the  other  hand,  mucous  membrane,  as  in  pro- 
lapsus of  the  rectum  and  vagina,  by  being  exposed  becomes 
dry,  and  assumes  all  the  peculiar  characters  of  skin. 

SKIN  AND  ITS  APPENDAGES. 


The  skin,  (cutis,  fopjta,)  as  already  remarked,  covers  the 
whole  external  surface  of  the  body,  and  according  to  the 
prize  essay  of  Mr.  Wheelock,  measures  in  extent  2,500  inches. 
Its  color  varies  from  white  to  black,  having  all  the  inter- 
mediate shades  depending  on  the  different  races  of  man- 
kind, and  the  difference  in  climate,  age  and  exposure.  Its 
density  also  varies,  being  thicker  in  the  black  than  the 
white,  and  much  more  dense  in  some  parts  of  the  body 
than  others,  as  in  the  palm  of  the  hand  and  sole  of  the 
foot.  It  has  two  surfaces,  the  one  free  and  exposed  to 
external  bodies,  the  other  adherent  to  parts  beneath  by  cel- 
lular tissue,  and  in  the  scalp  and  neck,  closely  connected  with 
muscular  structure,  as  over  the  occipito-frontalis  and  pla- 
tyma  myoides.  The  free  surface  presents  a  variety  of  ob- 
jects of  study,  as  inequalities  of  elevation  and  depression, 
folds  and  wrinkles,  openings  or  pores,  and  various  grades  of 
softness  and  moisture,  all  of  which  will  be  more  particular- 
ly noticed  in  the  account  of  its  structure.  The  adhering  sur- 
face, by  its  loose  cellular  tissue,  generally  admits  of  free 
motion  between  the  skin  and  adjacent  parts. 


SKIN  AND  ITS  APPENDAGES. 


125 


FIG.  19. 


The  structure  of  the  skin  consists  of  three  membranes — 
the  cutis  vera,  rete  mucosum,  and  cuticle. 

The  cutis-vera,  or  true  skin, 
is  the  innermost  layer  of  the 
three.  It  is  the  chief  mem- 
brane; is  the  thickest  and 
strongest,  and  is  regarded  as 
the  basis  to  the  other  two.  Ac- 
cording to  M.  M.  Beclard  and 
Bayle,  it  is  composed  of  cel- 
lulo-fibrous  structure,  in  the 
form  of  an  areolar  web,  more 
or  less  compact — that  is,  its 
cellular  fibres,  more  or  less 
interwoven  with  the  fibrous, 
form  a  firm,  compact  mem- 
brane, varying  in  thickness 
from  one-quarter  of  a  line  to  one  line  and  a  half.  Its 
thickness  in  the  trunk  is  greater  behind  than  before ;  in 
the  limbs  greater  externally  than  internally;  it  is  remark- 
ably dense  in  the  palms  of  the  hands  and  soles  of  the  feet, 
and  particularly  thin  in  the  eye-lids,,  mammse,  scrotum  and 
penis.  We  find  the  cellular  and  fibrous  tissue  varying  in 
their  relative  proportions  in  different  parts,  and  in  accord- 
ance with  the  amount  of  motion  and  resistance  to  press- 
ure; the  cellular  predominating  where  freedom  of  motion 
is  required,  as  in  the  axillae,  while  the  ligamentous  or 
fibrous  is  most  abundant  where  there  is  greatest  pressure, 
as  in  the  plantar  and  palmar  regions;  and  it  is  in  conse- 
quence of  this  combination  of  the  cellular  and  ligamentous 
tissue  in  the  cutis-vera,  that  we  find  it  possessed  of  the 

FIG.  19  represents  the  structure  of  the  skin,  a  Epiderma,  or  cuticle,  b 
Rete-mucosum.  c  Papillary  clumps,  quadrilateral  in  shape,  composed  of  coni- 
cal papillae,  and  seen  in  the  palm  of  the  hand  and  sole  of  the  foot,  d  Deep 
layer  of  derma,  the  corium.  e  Adipose  cells.  /  Sudoriparous  gland,  with  its 
spiral  duct,  g  Sudoriparous  gland,  with  a  straighter  duct,  as  seen  in  the  scalp. 
h  Two  hairs  from  the  scalp,  enclosed  in  their  follicles,  i  A  pair  of  sebi-parous 
glands,  opening  by  short  ducts  into  the  follicle  of  the  hair. 


126  SKIN  AND  ITS  APPENDAGES. 

properties  of  flexibility,  elasticity,  and  retractility.  It  also 
possesses  considerable  contractility,  as  seen  in  what  is 
called  the  goose  flesh,  and  in  the  scrotum,  nipples,  &c.,  and 
which  seems  to  depend  upon  some  reddish  fibres,  seen  im- 
mediately beneath  the  dermoid  tissue,  having  a  contractile 
property  and  resembling  involuntary  muscle. 

The  cutis-vera  contains  an  immense  number  of  blood  ves- 
sels, nerves  and  lymphatics,  which  ramify  through  its  sub- 
stance and  appear  upon  its  surface,  and  by  some  these  are 
considered  a  distinct  layer,  under  the  name  of  the  vascular 
retiform  layer  and  the  papillae,  though  not  generally 
regarded  as  a  distinct  and  separate  structure.  The  external 
surface  of  the  cutis-vera  has  numerous  elevations  or  pro- 
jections, called  papillae,  which  are  very  distinct  on  the 
extremities  of  the  fingers  and  toes,  and  on  the  palms  of 
the  hands  and  soles  of  the  feet.  On  the  fingers  these  pa- 
pillae present  the  form  of  arched  or  concentric  rows.  These 
rows  are  separated  by  longitudinal  and  transverse  fissures, 
which  it  is  said  give  passage  to  the  perspiratory  ducts. 

The  microscope  reveals  the  papillae  to  consist  of  blood 
vessels  and  nerves,  connected  by  cellular  tissue,  and  ter- 
minating in  loops.  The  nerves  are  seen  without  neuri- 
lemma,  and  the  blood  vessels,  according  to  Beclard,  have 
an  erectile  disposition.  These  papillae,  wherever  situated, 
are  the  seat  of  sensibility,  and  those  upon  the  ends  of  the 
fingers,  called  tactile  papillae,  are  the  especial  agents  of  the 
sense  of  touch.  Though  the  nerves  of  the  papillae  have 
been  said  to  terminate  in  loops,  yet  it  is  proper  to  say 
that  some  most  respectable  anatomists  assert  that  they  be- 
come so  soft  and  fine  that  it  cannot  be  determined  whether 
they  end  in  loops,  plexuses  or  soft  bulbs.  The  organic 
element  of  the  cutis  vera  is  principally  gelatin. 

The  rete-mucosum  is  the  next  layer  in  order,  and  covers 
the  outer  or  papillary  surface  of  the  cutis.  It  is  a  very 
soft  substance,  and  can  be  raised  in  a  distinct  layer,  though 
with  difficulty,  after  maceration.  M.  Galtier  makes  it  to 
consist  of  as  many  as  four  separate  laminae,  the  middle 
one  being  the  seat  of  color.  The  most  recent  micro- 


SKIN  AND   ITS   APPENDAGES.  127 

ecopic  observations,  however,  seem  to  regard  the  rete- 
mucosum  as  forming  the  internal  layer  of  the  cuticle,  and 
being  the  fresh  secreted  substance  from  the  cutis  vera, 
which  gradually  hardens  into  the  cuticle  as  it  approaches 
the  surface.  Henle  has  found  it  to  consist  of  small  oval 
cells,  containing  a  nucleus  which  became  hardened,  flat- 
tened, and  ultimately  changed  into  the  scales  of  the  cuticle. 

The  coloring  matter  is  also  found  to  be  produced  by 
cells,  called  pigment  cells — each  containing  a  nucleus,  and 
many  granules.  The  choroid  coat  of  the  eye,  it  is  said,  exhib- 
its the  pigment  cells  both  distinctly  and  beautifully.  The 
pigmentum  iiigruni  is  sometimes  absent  in  different  parts 
of  the  body,  as  in  the  eyes  of  Albinos — who  are  thereby  very 
sensitive  to  light. 

The  Cuticle,  Epidermis,  or  Scarf  Skin,  is  the  outermost 
or  most  external  layer  of  the  skin.  It  is  easily  separated 
by  blisters,  maceration,  or  putrefaction,  and  often  comes 
off  during  scarlet  fever;  on  raising  it,  it  is  seen  to  be  con- 
nected by  delicate  filaments  and  hairs  to  the  parts  beneath. 
It  consists  of  one  homogeneous  layer,  destitute  of  cellu- 
lar tissue,  vessels,  and  nerves.  When  separated,  it  pre- 
sents the  character  of  the  horny  tissue — is  hard,  and  varies 
greatly  in  thickness  in  different  parts,  according  to  press- 
ure; for  example,  it  is  thickest  in  the  palms  of  the 
hands  and  soles  of  the  feet ;  it  exactly  adapts  itself  to  all 
the  inequalities,  as  the  papillae  and  furrows  upon  the  cutis 
vera,  and  from  being  without  nerves  and  blood  vessels,  and 
consequently  without  sensation  •  and  circulation,  is  admi- 
rably suited  to  protect  the  very  delicate  and  sensitive  sur- 
face of  the  cutis  below.  At  the  mouth,  anus,  and  other 
natural  apertures,  it  is  continuous  with  the  epithelium  or 
cuticle  of  the  mucous  membrane. 

Under  the  microscope,  the  cuticle  consists  of  several  suc- 
cessions of  small,  hard,  dry  laminae  or  scales,  each  of  which 
contains  opaque  spots  of  the  original  nucleus  and  cells,  now 
flattened  into  scales,  of  an  irregular  form,  overlapping 
each  other  at  their  edges,  and  constantly  desquamating  or 
falling  off  like  particles  of  bran.  It  is  nothing  more  than 


128  SKIN  AND  ITS  APPENDAGES. 

the  secreted  fluid  from  the  cutis-vera,  thrown  out,  it  would 
seem,  like  varnish  over  the  whole  surface  of  the  body,  and 
then  condensing  and  hardening  into  the  scales  just  men- 
tioned. 

The  process  of  formation  is  thus  seen  by  the  microscope. 
The  capillaries  of  the  cutis-vera  throw  out  lymph,  contain- 
ing numerous  cell-germs ;  these  soon  enlarge  into  cells, 
and  closely  apply  themselves  to  the  surface  of  the  cutis. 
When  this  layer  is  completed  a  second  layer  forms  beneath, 
and  the  first  then  becomes  separated  from  the  true  skin, 
changes  its  form  and  consistence,  becomes  flat  and  hard, 
and,  by  evaporation,  dry  and  firm,  and  finally  falls  off  in 
scales ;  and  this  succession  of  changes,  from  the  primitive 
secreted  nucleus  of  the  cell  germ,  up  to  the  dry  flattened 
desquamating  scale,  is  continually  going  on. 

The  cuticle  is  flexible,  elastic,  and  easily  torn.  Boiling 
water  extracts  some  gelatine,  renders  it  white,  opaque, 
and  deprives  it  of  elasticity.  When  dry,  its  volume  is  di- 
minished, becomes  firmer,  slightly  yellowish,  and  resists 
putrefaction  for  a  long  time,  Fire  causes  it  to  burn  like 
horn  and  emit  a  similar  odor.  The  fixed  alkalies  resolve 
it  into  a  soapy  substance.  Nitric  acid  turns  it  yellow 
almost  immediately,  and  thickens,  softens  and  reduces  it 
to  a  pulp  in  twenty-four  hours. 

The  skin  thus  constituted  of  the  cuticle,  rete-mucosum, 
and  cutis-vera,  has  its  external  surface  moistened  by  two 
kinds  of  fluids — the  one  watery  in  its  nature,  called  the 
perspiration — the  other  unctuous  in  its  character,  and 
known  as  the  sebaceous. 

The  perspiration,  which,  when  augmented  in  quantity, 
becomes  the  sweat,  is  furnished  by  follicles  called  the  sudo- 
riferous or  sweat-glands,  (Fig.  19 ;)  they  are  found  in  all 
parts  of  the  skin,  are  of  a  round  form,  and  consist  of  a 
co3ca,  ending  in  a  spiral  tube,  the  exhalent  duct,  which 
passes  through  the  cutis,  rete-mucosum,  and  cuticle,  open- 
ing on  the  latter  by  a  minute  pore.  In  the  axillae  they  are 
described  as  large,  very  distinct,  and,  by  their  reddish  color, 
readily  distinguished  from  the  fatty  grains  adjoining  them. 


SKIN  AND  ITS  APPENDAGES.  129 

The  sebaceous  or  oily  fluid  comes  from  sebaceous  glands. 
These,  though  not  so  numerous  as  the  perspiratory,  are 
nevertheless  abundant  in  many  parts  of  the  skin,  as  the 
nose,  face,  arm-pits,  arms,  &c.;  the  palms  of  the  hands  and 
soles  of  the  feet  being  destitute  of  them.  They  present  a 
variety  of  form,  from  the  simple  sac-like  follicle  to  the 
lobulated  gland.  In  the  scalp  the  lobes  are  clustered  to- 
gether like  a  bunch  of  grapes ;  and  their  ducts,  which  are 
straight,  though  sometimes  spiral,  besides  perforating  the 
skin,  have  one  or  more  of  them  entering  the  hair  follicle. 
(Fig.  19.)  These  ducts  are  lined  by  the  involuted  cuticle. 
The  meibomian  glands  of  the  eye-lids,  and  the  ceruminous 
glands  of  the  ear,  are  also  examples  of  sebaceous  glands. 

The  sebaceous  glands  are  about  the  size  of  millet  seed, 
of  a  yellow  color,  and  most  generally  situated,  as  well  as 
the  perspiratory,  in  the  subcutaneous  cellular  structure, 
though  sometimes  imbedded  in  the  dermis  itself. 

There  is  another  set  of  glands  belonging  to  the  skin, 
called  the  odoriferous  glands,  (glandules  odoriferse,)  which 
are  very  particularly  described  by  Dr.  Homer,  who  seems 
to  have  given  them  more  attention  than  any  previous 
anatomist.  He  says  they  are  well  developed  in  the  negro, 
and  are  found  in  the  arm-pit,  near  the  skin,  and  enveloped 
in  cellular  adipose  structure.  About  three  hundred  of 
these  glands  were  counted  on  a  space  the  size  of  a  Spanish 
dollar ;  they  are  described  as  of  a  brown  color,  of  varying 
size,  from  a  line  to  two  lines  in  length,  and  having  a  gran- 
ular surface,  like  the  mammary  and  pancreatic  glands. 
Their  use  is  believed  to  be  to  furnish  the  odorous  secretions 
of  the  body. 

The  Functions  of  the  skin  are  those  of  Sensation,  Secre- 
tion, and  Absorption. 

Sensation,  as  already  stated,  is  either  general  or  special — 
every  part  of  the  skin  being  supplied  with  nerves — so,  in 
every  part  we  find  common  sensibility,  or  tact,  while  spe- 
cial sensibility,  or  sense  of  touch,  is  very  limited,  confined 
almost  exclusively  to  the  tips  of  the  fingers.  By  this  func- 
tion the  health  and  preservation  of  the  body  is  particularly 
9 


130  SKIN  AND  ITS  APPENDAGES. 

looked  after ;  it  stands,  as  the  faithful  sentinel,  on  the  out- 
posts of  the  system,  giving  immediate  warning  whenever 
an  enemy  is  at  hand,  or  an  injury  is  suspected,  whether 
by  mechanical  or  chemical  violence  or  the  temperature  of  the 
atmosphere.  This  warning  is  by  the  sensation  of  pain. 
But  this  function  is  also  intellectual,  as,  by  the  sense  of 
touch,  it  is  the  medium  of  knowledge  to  the  mind.  '» 

The  Secretion  of  the  skin  has  been  stated  to  be  perspira- 
tory and  sebaceous.  By  this  function  the  properties  of 
smoothness,  softness,  and  pliability  are  imparted  to  the 
skin,  and  a  large  amount  of  superfluous  matter  thrown 
off,  which,  if  retained,  would  destroy  life. 

The  amount  of  exhalation  from  the  skin  has  been  esti- 
mated by  Sanctorius.  It  is  stated  that  for  thirty  years  he 
daily  weighed  his  body,  food,  and  excretions.  His  estimate 
was,  that  out  of  every  eight  pounds  of  nourishment,  five 
passed  off  by  the  skin,  leaving  only  three  to  be  carried  off 
by  the  lungs,  kidneys  and  bowels.  M.  Seguin  made  the 
amount  average  about  three  pounds  in  the  twenty-four 
hours*  Twenty  or  thirty  ounces  of  this  exhalation,  it  is 
said,  cannot  accumulate  in  the  system  without  causing 
disease;  which  is  no  doubt  true.  The  perspiratory  func- 
tion is  also  one  of  refrigeration,  as  by  evaporation  the 
body  is  cooled. 

Absorption,  though  at  one  period  denied  to  the  skin,  is 
now  fully  established  as  one  of  its  functions;  for  by  the 
skin  many  articles  of  the  materia  medica  are  daily  intro- 
duced into  the  system,  and  produce  their  effects  with  nearly 
the  same  certainty  as  when  taken  by  the  mouth. 

The  Relations  of  the  skin  may  be  considered  as  Physical, 
Chemical,  Organic,  and  Mental. 

The  principal  physical  relation  of  the  skin  is  atmos- 
pheric air,  of  a  certain  temperature  and  density.  If  the 
temperature  be  too  low,  the  skin  will  become  cold,  torpid, 
and  frozen,  while  the  function  of  sensation  will  be  ob- 
scured, benumbed,  or  entirely  lost,  and  those  of  secretion 
and  absorption  completely  checked  or  destroyed.  On  the 
other  hand,  if  the  temperature  be  too  high,  the  violence 


SEIN  AND  ITS  APPENDAGES.  131 

of  action,  will  result  in  the  disturbance  and  destruction  of 
its  functions. 

The  relation  of  the  skin  with  the  density  of  the  atmos- 
phere is  equally  fixed  and  important  During  an  ascent  to 
the  top  of  Mont  Blanc,  where  the  air  is  so  much  more  rare, 
the  cohesive  property  of  the  skin  gives  way  for  want  of 
pressure ;  a  general  relaxation  occurs,  and  the  blood,  we 
are  told,  flows  from  the  whole  surface  of  the  body.  Too 
great  density,  on  the  other  hand,  would  be  equally  de- 
structive. 

In  regard  to  the  Chemical  relations  of  the  skin,  it  is 
well  known  that  if  chemical  agents  be  not  applied  in  their 
due  and  proper  proportion,  they  are  violently  destructive,  at 
once  disorganizing  the  skin,  breaking  up  its  whole  texture, 
and,  consequently,  destroying  all  its  functions. 

The  skin,  being  an  organ,  and  forming  part  of  the 
body,  becomes  necessarily  connected  with,  and  more  or  less 
dependent  on,  every  other  part  or  organ ;  and  hence  it  has 
organic  relations.  The  principal  of  these  are  with  the 
mucous  membrane  and  kidneys.  When  the  functions 
of  these  organs  are  increased,  those  of  the  skin  are  dimin- 
ished, and  vice  versa. 

The  Mental  Relations  of  the  skin,  or  those  it  has  with 
the  brain  and  nervous  system,  are  equally  striking.  Every 
one  has  seen  fear  and  grief  contract  the  skin,  and  render 
it  pale,  cold,  bloodless,  benumbed,  deprived  both  of  sensa- 
tion and  secretion.  Anger  and  joy,  on  the  contrary, 
dilate  the  skin,  fill  it  with  fluids,  increase  its  color, 
excite  all  its  functions,  and,  if  in  excess,  will  as  certainly 
injure  and  derange  them. 

Now  these  several  relations  constitute  so  many  fixed  and 
definite  laws  for  the  regulation  of  the  skin's  functions — 
obedience  to  which  has  the  high  reward  of  health  and  life; 
disobedience,  the  penalty  of  disease  and  death.  The  pen- 
alty is  inflicted  in  a  variety  of  ways,  as  in  vices  of  confor- 
mation, congenital  and  acquired,  accidental  productions,  as 
fistulas,  abscesses,  morbid  secretions  of  the  sebaceous  folli- 
cles, having  names  according  to  the  kind  and  consistency 


132  APPENDAGES  OF  THE  SKIN. 

of  the  fluid;  a  variety  of  tumors  of  varied  size  and  charac- 
ter, as  the  steotoma,  atheroma,  meliceris,  &c.,  or  a  fatty,  a 
pulpy,  and  a  honey-like  tumor;  and,  finally,  inflammation 
in  all  its  various  forms. 

APPENDAGES  OP  THE  SKIN. 

The  appendages  of  the  skin  consist  of  the  hairs  and 
nails,  which  are  modifications  of  the  cuticle. 

The  hairs  (Fig.  19)  present  differences,  according  to 
their  situation,  in  length,  fineness,  delicacy,  quantity, 
size,  and  color.  They  differ  according  to  races,  being 
long,  fine,  thick,  and  often  curled,  in  the  Caucasian  and 
Malay,  fine  and  thin  in  the  American,  short  and  coarse 
in  the  Mongolian,  and  crisped  and  woolly  in  the  Ethio- 
pian. They  vary  also  with  age  and  sex,  being  finer  in 
the  young  than  in  the  old,  and  in  the  female  than  in  the 
male. 

Each  hair  is  composed  of  a  bulb  and  stem.  The  bulb 
is  simply  a  reflection  of  the  skin,  termed  the  follicle,  con- 
taining a  conical  pulpy  substance  called  the  papilla.  The 
follicle  is  ovoid  in  shape,  and  lined  by  the  involuted  cuticle ; 
it  is  embedded  in  the  subcutaneous,  adipose,  and  cellular 
structure,  and  is  highly  vascular  and  sensitive.  The  pa- 
pilla is  the  part  of  the  bulb  generating  the  hair;  from  its 
vessels,  lymph  is  poured  out  containing  cell  germs;  these 
grow  into  cells  with  nuclei,  which  elongate  and  become 
condensed  into  scales,  overlapping  each  other,  and  form- 
ing the  cortex  or  outer  surface  of  the  hair. 

The  hair  lengthens  by  fresh  successive  additions  from 
the  papilla,  one  beneath  the  other,  constantly  repeated, 
as  long  as  it  continues  to  grow. 

The  interior  of  the  hair,  called  the  medulla,  has  its  cells 
less  condensed  than  the  outer,  and,  on  a  transverse  sec- 
tion, gives  the  appearance  of  a  cell-tube. 

Hair  can  be  split,  and  of  itself  separates  into  filaments. 
Pigment  granules  are  found  in  the  cells  of  the  bulb,  on 
which  the  color  depends;  and  into  the  follicle  the  ducts 
of  one  or  more  of  the  sebaceous  glands  open  and  discharge 


APPENDAGES  OF  THE  SKIN.  133 

their  fluids,  which,  it  is  said,  lubricate  the  hair  throughout 
its  whole  course.  (See  Fig.  19.) 

The  formative  force  is  very  great  in  hair.  It  is  quickly 
replaced  when  cut  or  destroyed,  provided  the  bulb  and 
papilla  remain  uninjured.  Hair  is  entirely  destitute  of 
vitality,  except  at  its  root  or  bulb,  where  it  is  both 
vascular  and  sensitive,  as  seen  in  the  disease  called  plica- 
polonica. 

The  motions  of  the  hair  are  referred  to  the  action  of  sub- 
cutaneous muscles.  This  is  very  evident  in  the  large  hairs 
or  prickles  of  the  porcupine,  and  the  feathers  of  the  tail  of 
the  peafowl,  where  each  is  supplied  with  a  distinct  muscle 
for  its  elevation. 

Hair,  like  the  cuticle,  resists  putrefaction  for  a  long 
-time.  Boiling  resolves  it  into  gelatin  and  coagulated 
albumen.  According  to  Vauquelin,  hair  is  composed  of 
an  animal  matter  which  forms  the  base — a  small  quantity 
of  a  white  concrete  oil,  a  blackish  oil,  iron,  oxide  of  manga- 
nese, carbonate  of  lime,  silex,  and  sulphur. 

The  Nails  are  the  horny  scales  which  cover  the  last 
phalanx  of  the  fingers  and  toes.  Each  nail  consists  of  a 
root,  body,  and  free  extremity.  The  root  and  borders  are 
confined  in  a  fold  of  the  cutis,  named  the  nail-follicle;  the 
body  rests  upon  the  surface  of  the  cutis,  called  the  matrix, 
which  is  very  vascular,  and  appears  red;  while  the  white 
portion,  just  at  the  root,  is  styled  the  lunula.  The  nail 
grows  in  a  manner  similar  to  the  cuticle. 

The  nail  follicle  and  matrix  contain  papillae,  that 
secrete  the  fluid  or  lymph  in  which  are  found  cell-germs. 
These,  like  those  of  the  hair,  become  compressed,  dry,  flat- 
tened and  hardened  into  nail :  those  at  the  root  elongating 
and  adding  to  the  length;  those  at  the  borders  forming 
the  breadth;  while  those  in  the  matrix,  or  centre,  increase 
the  thickness. 

The  nails  protect  and  form  a  firm  support  to  the  tactile 
papillae  or  organs  of  touch.  They  are  also  instruments  of 
prehension. 


134  THE  MUCOUS  MEMBRANE. 

THE  MUCOUS  MEMBRANE. 

This  constitutes  the  second  division  of  the  Cutaneous  Sys- 
tem. It  lines  the  whole  interior  of  the  surface  of  the  body, 
having  communication  with  the  exterior  world.  It  is 
consequently  coextensive  with  the  digestive,  pulmonary, 
urinary,  and  genital  organs.  It  is  continuous,  as  before 
stated,  with  the  skin.  Its  color  varies  from  a  pale  rose  to 
a  beautiful  red.  Its  density  also  varies,  being  thinner  in  the 
urethra  and  genital  organs  than  in  the  intestines.  Its 
tenacity  is  so  slight,  it  tears  easily  in  the  attempt  to  raise  it. 

Like  the  skin,  it  has  two  surfaces,  the  one  free,  the  other 
adherent.  The  free  surface  presents  valvulee,  folds  and 
wrinkles,  cavities  or  depressions,  and  papillary  and  villous 
projections.  The  adhering  surface  is  covered  by  a  fibro 
cellular  tissue,  which  gives  the  mucous  membrane  its 
solidity.  It  has  two  principal  divisions. 

1st.  The  gastro-pulmonary. 

2d.  The  genito  urinary. 

The  first  division  lines  the  mouth,  where  it  is  continuous 
with  the  skin  of  the  lips,  and  successively  the  pharynx, 
oesophagus,  stomach,  and  intestines,  to  the  anus,  where  it 
again  runs  into  the  skin.  In  this  route  it  sends  off  numer- 
ous prolongations  to  all  the  excretory  ducts  of  the  glands, 
communicating  with  the  alimentary  canal,  as  the  salivary 
glands,  tonsils,  liver  and  pancreas.  It  extends  to  the  nose 
under  the  name  of  pituitary  membrane,  lining  it  and  the 
different  sinuses.  Through  the  nasal  and  lachrymal  duct  it 
reaches  the  eye,  covering  the  interior  of  the  eyelids,  and  the 
globe  of  the  eye.  From  the  back  part  of  the  mouth  we  follow 
it  in  one  direction  through  the  Eustachian  tube,  into  the 
cavity  of  the  tympanum,  and  the  mastoid  cells,  by  another 
route  we  trace  it  into  the  larynx  trachea,  bronchi,  and  all 
.their  ramifications  in  the  lungs. 

The  2d  division  or  genito  urinary,  beginning  at  the  glans 
penis,  is  found  lining  the  urethra,  bladder,  ureters,  infundi- 
bulum,  and  even  calyces  of  kidneys,  while  in  the  female  it 
also  covers  the  labia,  clitoris,  and  vagina. 


THE  MUCOUS  MEMBRANE.  135 

The  mucous  membrane  presents  different  appearances  in 
the  different  organs  it  traverses.  It  is  disposed  in  longitu- 
dinal folds,  is  thick  and  loosely  attached  to  the  muscular 
coat  in  the  oesophagus.  It  presents  the  form  of  plaits 
or  rugae  in  the  stomach,  and  of  valvulaa  conniventes  in  the 
upper  intestines. 

The  structure  of  the  mucous  membrane  is  very  analogous 
to  that  of  the  skin,  and  like  it,  consists  of  three  membranes, 
an  epithelium,  a  proper  mucous  and  a  fibrous  coat.  The 
epithelium  corresponds  with  the  cuticle,  and  consists  of 
nuclei,  vesicles,  and  scales.  It  has,  until  very  recently,  been 
considered  as  extending  inwardly  only  to  the  cardiac  ori- 
fice of  the  stomach,  but  by  the  microscope  it  now  seems  to 
be  satisfactorily  established  as  covering  the  whole  extent 
of  the  mucous  surface  wherever  found. 

The  epithelium  presents  a  variety  of 
forms  in  different  situations.  In  the 
mouth  (Fig.  20)  it  assumes  the  shape  of 
laminae,  the  nuclei  or  cytoblasts  forming 
the  deepest  layer,  then  upon  these  are  the 
cells,  and  upon  these  again  the  topmost 
layer  of  polygonal  scales,  which  become  thin  and  flattened, 
and  constitute  the  highest  stage  of  development  from  the  cell 
germ  or  nucleus.  The  nuclei,  cells  and  scales  are  connected 
by  a  glutinous  substance,  in  which  are  found  opaque  gran- 
ules. The  scales  are  constantly  exfoliating,  and  give  place 
to  the  deeper  layer,  which  in  their  turn  give  way  to  others, 
and  so  in  perpetual  succession,  there  is  a  perpetual  waste 
and  supply. 

In  the  stomach  and  intestines,  the  epithelium  (Fig.  21) 
has  the  columnar  or  cylindrical  shape,  the  apices  of  the 
columns  resting  on  the  papillary  coat,  while  the  bases,  by 
their  approximation,  form  the  free  surface.  Each  column 
has  its  nuclei,  cells  and  scales,  and  is  produced  in  the  same 
way  as  the  laminated  epithelium,  and  also  undergoing  the 
constant  waste  and  supply. 

FIG.  20.  Epithelium  scales  from  inside  of  the  mouth. 


136 


THE  MUCOUS  MEMBRANE. 
FIG.  21. 


The  columnar  form  of  epithelium  is  also  found  in  all  the 
glandular  ducts,  whose  bases  are  often  surmounted  with 
cilite,  (Fig.  22,)  whose  motions  are  directed  towards  the 
FIG.  22.  outlets  of  the  canals  they  line. 

The  second  coat,  the  proper  mu- 
cous, called  also  the  papillary  or 
basement  membrane,  resembles 
the  papillary  layer  of  the  skin, 
and  is  a  membrane  apparently  without  texture.  Its  sur- 
face presents  different  aspects  at  different  points. 

In  the  stomach  it  forms  cells  or  alveoli,  into  which  the 
follicles  open.  In  the  intestines  it  presents  numerous  pro- 
jecting points,  having  a  velvety  appearance  and  called 
villi,  while  in  the  large  intestines  it  again,  as  in  the 
stomach,  assumes  the  shape  of  cells.  This  coat  is  exceed- 
ingly soft  and  spongy,  easily  destroyed  either  by  mechani- 
cal violence  or  the  action  of  acids,  which  reduces  it  to  a 
pulpy  state. 

The  fibrous  layer,  called  also  the  sub-mucous  and  nervous, 
forms  the  third  layer  of  mucous  membrane.  It  corresponds 
to  the  corium  of  the  skin,  in  giving  support  and  strength  to 
the  mucous  layer,  and  contains  numerous  capillary  vessels, 
nerves  and  absorbents. 

It  has  just  been  stated  that  the  mucous  membrane  has 
upon  its  papillary  surface  numerous  conical  projections, 

FIG.  21  represents  cylinders  of  the  Intestinal  Epithelium. 

1  Cylinders  from  cardiac  region  of  the  human  stomach.  2  Cylinders  from 
jejunum.  3  Cylinders  seen  from  their  free  extremity.  4  Cylinders  as  seen  in 
a  transverse  section  of  a  villous. 

FIG.  22,  Ciliated  Epithelium.    6  Cilia  upon  the  top  of  a  epithelium. 


THE  MUCOUS  MEMBRANE.  137 

called  villi  from  their  velvety  appearance,  or  their  resem- 
blance to  the  down  of  an  unripe  peach. 

Each  villus  consists  of  blood  vessels,  nerves  and  absorb- 
ents bound  together  by  cellular  tissue,  and  not  only  cov- 
ered by  epithelium,  but  also,  it  is  said,  by  an  additional  fine 
membrane.  These  villi  give  origin  to  the  lacteals  by  fine 
branches,  which,  it  is  now  found,  do  not  have  open  orifices 
upon  their  surface  as  formerly  believed,  but  between  the 
capillary  vessels  at  the  extremity  of  each  villus,  while 
chylous  absorption  is  going  on,  are  seen  cells  containing 
an  opalescent  fluid.  These  cells  disappear  almost  entirely, 
it  is  said,  when  the  chyle  has  left  the  intestine;  the  lac- 
teals  empty  themselves,  and  the  villi  become  flaccid. 

These  cells  are  regarded  as  the  special  agents  for  select- 
ing the  nutrient  matter  and  handing  it  over  to  the  lacteals ; 
they  have  a  short  life,  and  are  constantly  being  renewed. 
Another  element  of  mucous  membrane  is  found  in  the 
follicles  and  glands  scattered  throughout  its  whole  extent. 

The  simple  follicles  of  Leiberkuhn  exist  in  immense 
numbers  every  where  upon  the  mucous  surface.  They  con- 
sist simply  of  depressions  of  the  mucous  surface,  forming 
small  pouches,  whose  orifices  are  not  visible  to  the  naked 
eye,  but  which  are  found  to  have  eight  or  ten  times  the 
diameter  of  the  red  globules  of  blood. 

Professor  Homer  has  estimated  the  number  of  these  fol- 
licles to  be  about  25,000  to  the  square  inch,  and  between 
forty  and  fifty  millions  to  the  whole  alimentary  canal. 
Their  use  is  to  supply  the  principal  part  of  the  mucous 
fluid.  The  glands  are  simply  compound  cryptce  or  folli- 
cles, having  different  forms  and  names,  in  different  parts  of 
the  mucous  membrane. 

At  the  mouth  of  the  Eustachian  tube,  the  simple  follicles 
are  collected  in  a  body  of  somewhat  oval  form  and  almond 
size,  called  the  tonsil.  In  the  oesophagus  these  follicles  are 
situated  in  the  sub-mucous  tissue,  and  lobulated,  communi- 
cating with  the  surface  by  a  long  excretory  duct. 

In  the  stomach  the  glands  are  seen  in  the  shape  of  long 
tubes,  situated  perpendicularly,  side  by  side,  and,  at  their 


138 


THE  MUCOUS  MEMBRANE. 


terminations,  dilated  into  small  pouches,, 
having  a  clustered  appearance.  These  are 
supposed  to  secrete  the  gastric  fluid. 

In  the  duodenum  is  another  set  of  glands 
called,  after  their  discoverer,  Brunner's 
Glands.  (Fig.  24.) 

FlG-  24-  They  are  small,  granular, 

and  flattened,  and  compared 
to  the  pancreas  and  salivary 
glands;  each  granule  consist- 
ing of  minute  lohules  or  cells, 
all  of  which  open  upon  the 
surface  by  a  common  duct.  In 
the  lower  part  of  the  ileum 
are  the  glandulae  agminata3,or 
Peyer's  glands.  (Fig.  25.)  They 
are  found  most  abundant 
about  the  junction  of  the  ile- 
um with  the  colon,  and  op- 
posite the  attachment  of 
the  mesentery.  They  are 
Collected  in  numerous 
small  circular  patches,  sur- 
rounded by  the  simple  fol- 
licles. Each  is  simply  a 
closed  sac,  having  no  ex- 
cretory duct,  as  far  as  ob- 
servation has  gone,  and, 
when  ruptured,  is  found  to 
contain  mucus  and  small 
cells.  Their  use  is  not  known.  It  is  thought  by  some 
that  ulceration  of  Peyer's  glands  constitutes  the  essential 

FIG.  23  represents  a  portion  of  the  mucous  membrane  of  the  stomach,  show- 
ing the  pits  upon  its  surface,  and  where  the  tubes  from  the  gastric  glands  enter. 

FIG.  24  represents  a  portion  of  one  of  Brunner's  glands  from  the  human 
duodenum— magnified  65  diameters. 

FIG.  25  represents  a  portion  of  one  of  the  patches  of  Peyer's  glands  at  the 
termination  of  the  ileum. 


THE  MUCOUS  MEMBRANE.  139 

element  in  typhoid  fever,  while  others  regard  such  lesion 
simply  a  result  of  the  latter. 

There  is  another  set  of  glands  "belonging  to  the  mucous 
membrane,  called  the  Grlandulge  Solitarige,  or  Solitary 
Glands.  These  are  of  two  kinds — those  having  excretory 
ducts,  or  openings,  and  those  without.  The  first  are  found 
in  the  large  intestine,  being  most  abundant  in  the  coecum. 
The  second  are  seen  in  the  small  intestine,  in  the  form  of 
small  circular  patches,  surrounded  by  a  wreath  of  simple 
follicles,  and,  when  opened,  present  a  small,  saccular,  flat- 
tened cavity,  holding  mucus. 

Dr.  Homer,  who  has  paid  much  attention  to  the  investi- 
gation of  the  minute  anatomy  of  the  mucous  membrane, 
seems  to  think,  from  his  observations  during  the  chol- 
era, and  minute  injections  of  this  membrane,  that  it  "con- 
sists almost  entirely  of  a  cribriform  intertexture  of  veins ;" 
and,  in  death,  these  veins  being  empty,  are  soft  and  spongy, 
and  give  the  velvety  appearance  of  ordinary  descriptions. 
The  arteries  are  described  as  few  in  number,  and  situated 
beneath  the  venous  intertexture,  and  much  smaller  than 
the  corresponding  veins.  The  meshes  in  this  venous  inter- 
texture are  very  minute,  and  are  considered  as  the  simple 
follicles  of  Lieberkuhn,  resting  upon  the  arterio-venous 
layer  and  cellular  structure  below  as  their  basis.  Dr.  Homer 
is  led  to  believe,  from  this  anatomical  arrangement  of  the 
mucous  membrane,  that  the  functions  of  these  follicles  are 
rather  for  absorption  than,  as  generally  supposed,  for  secre- 
tion. As  the  Fallopian  tube,  by  a  vascular  turgescence, 
erects  itself  and  grasps  the  ovum,  in  like  manner,  says  the 
doctor,  "  as  these  intestinal  follicles  are  formed  in  the  midst 
of  veins,  their  orifices  only  become  erect  and  patulous  by 
the  distension  of  those  veins,  and  cannot  be  well  seen  by 
the  eye  alone,  unless  an  injection  has  fully  succeeded.  But 
the  erection  of  these  veins,  during  digestion,  puts  the  folli- 
cles in  a  similar  condition;  there  is,  therefore,  some  ground 
of  inference  that  the  act  of  the  Fallopian  tube  in  conveying 
a  germ,  and  of  a  follicle  in  conveying  into  the  thickness 
of  an  intestine  congenial  matter,  may  be  analogous." 


140  THE  MUCOUS  MEMBRANE. 

Again,  this  same  anatomist  universally  found  the  sur- 
faces of  the  villi  polished,  and  not  presenting  any  foramina, 
while  many  of  the  follicles  were  found  passing  obliquely 
into  their  bases.  In  a  word,  the  gastro-enteric  follicles, 
situated  in  the  venous  intertexture  above  described,  and 
considered  as  identical  with  its  meshes,  are  regarded  as 
the  absorbing  agents  of  the  chyle,  which  conduct  it  into 
the  lacteals. 

The  functions  of  the  mucous  membrane  are,  like  those  of 
the  skin,  sensation,  secretion,  and  absorption.  Besides  the 
common  sensation  of  the  whole  membrane,  and  the  special 
sense  of  taste  as  belonging  to  it,  and  seated  in  the  tongue, 
the  feelings  or  appetites  of  hunger  and  thirst  are  also  re- 
ferred to  this  membrane.  Its  secretions  are  those  of  serum 
and  mucus,  &c.,  and  it  absorbs,  as  already  stated,  the  chyle 
with  other  matters. 

The  relations  of  the  mucous  membrane  are  as  fixed  as 
those  of  the  skin,  and  are,  chiefly  the  physical,  chemical, 
and  organic. 

The  principal  physical  relations  are  those  it  has  with 
food  and  water. 

It  is  well  known  that  our  food  and  drink  enter  the  sys- 
tem mainly  through  this  structure,  and  if  we  attempt,  in 
the  healthy  state  of  this  membrane,  to  substitute  any  thing 
else  in  place  of  the  natural  stimuli,  there  will  certainly 
be  more  or  less  lesion  and  disturbance  of  its  functions. 
For  instance,  if  we  swallow  poison,  in  place  of  food,  there 
is  the  greatest  danger  not  only  of  disturbance,  but  of  com- 
plete destruction  to  both  structure  and  function,  by  the 
most  rapidly  violent  and  destructive  inflammation.  And 
this  example  further  shows  the  chemical  relations  of  this 
membrane  to  be  equally  fixed,  and  necessary  to  be  observed, 
for  the  preservation  of  its  integrity. 

Its  organic  relations  are  most  important,  both  in  health 
and  disease,  as  it  sympathizes  with,  and  is  the  channel  of 
intercourse  to  every  other  part  and  organ  of  the  body. 

Now,  these  several  relations,  as  in  the  case  of  the  skin, 
constitute  so  many  fixed  laws — obedience  to  which,  we 


THE  MUSCULAR  TISSUE.  141 

equally  find,  has  the  reward  of  health  and  life,  and  diso- 
bedience the  penalty  of  disease  and  death.  The  penalties 
refer  to  the  pathological  state  of  this  membrane,  the  prin- 
cipal of  which  consist  in — 

Malformations ,  congenital  or  acquired,  as  seen  in  oblite- 
ration of  the  rectum. 

Displacements ,  as  in  prolapsus  of  the  vagina. 

Stricture,  as  in  the  urethra. 

Tumor,  as  polypi  of  the  nose  and  uterus. 

Vegetations. 

New  Formations,  as  cartilage,  bone,  hair,  &c. 

Discharges,  as  serum,  mucus,  blood. 

Inflammation,  with  all  its  terminations  in  suppuration, 
nlceration,  and  gangrene. 

The  appendages  of  the  mucous  membrane  are  the  Teeth ; 
which  see  in  another  part  of  the  work. 


CHAPTER  VII. 
THE   MUSCULAR   TISSUE. 

ANALYSIS. 

DEFINITION,   IMPORTANCE,   DIVISION,    FORM,   COLOR,    SIZE,  CONSISTENCE,  COURSE, 

NUMBER,   ATTACHMENTS,   NOMENCLATURE,    STRUCTURE,    FUNCTIONS, 

DEVELOPMENT. 

Muscle  (from  /wvwv,  a  muscle,  or  ^tuj,  a  mouse,)  is  the  ac- 
tive organ  of  motion  in  the  different  parts  of  the  body.  In 
familiar  language,  it  is  called  the  flesh,  and,  by  its  pro- 
perty of  contraction,  is  connected  with  many  of  the  most 
important  functions.  The  importance  of  this  tissue  may 
be  estimated,  when  we  consider  that  the  functions  of  diges- 
tion, respiration,  circulation,  locomotion,  speech,  and  ex- 
pression, are  all  dependent  upon  it.  Muscles,  as  we  shall 
presently  see,  consist  of  bundles,  mostly  of  reddish  fibres, 
of  variable  size  and  strength,  and  have  a  head,  body,  and 
tail,  or,  in  more  anatomical  language,  an  origin,  course, 


142  THE  MUSCULAR  TISSUE. 

and  insertion.  The  muscles,  collectively,  form  the  mus- 
cular system.  They  have  been  arranged  under  two  grand 
divisions. 

1st.  The  Voluntary,  or  all  those  subject  to  the  control  of 
the  will.  2d.  The  Involuntary,  or  those  over  which  the 
will  has  no  influence.  A  third  division  is  made,  called  the 
Mixed  class  of  Muscles,  which  is  a  compound  of  the  other 
two,  over  which  the  will  has  only  partial  control,  as  seen 
in  most  of  the  Sphincters. 

The  first  class  are  by  far  the  most  numerous,  and  situ- 
ated chiefly  upon  the  face  and  extremities — composing  the 
greater  bulk  of  the  organs  of  relation.  The  second  class 
belong  to  the  organs  of  nutrition,  comprising  the  stomach, 
intestines,  heart,  &c.  Muscles  are  either  arranged  in  pairs 
or  are  symmetrical.  The  first  are  found  upon  either  side 
of  the  median  line  of  the  body,  perfectly  distinct,  wide 
apart,  and  each  exactly  alike,  as  upon  the  limbs;  or  they 
may  approach  so  close  along  the  middle  line  as  to  touch 
6ne  another,  but  still  preserve  their  perfect  distinctness 
of  separation.  The  symmetrical  muscles  are  situated  pre- 
cisely upon  the  median  line,  and  consist  in  two  equal  and 
similar  halves. 

Muscles,  according  to  their  form,  are  distinguished  into 
the  long,  the  flat  or  wide,  and  the  short.  The  long  mus- 
cles are  generally  placed  upon  the  limbs,  to  the  beauty 
and  conformation  of  which  they  very  much  contribute. 
The  wide  are  mostly  situated  upon  the  parietes  of  cavi- 
ties, as  those  of  the  chest  and  abdomen,  and  "serve  to 
protect  the  internal  organs,  aid  their  functions,  and  move 
the  body  or  the  limbs,  as  the  one  or  the  other  is  the  fixed 
point."  The  wide  muscles,  generally,  are  not  very  thick — 
in  some  places  resembling  a  thin  membrane,  as  the  broad 
muscle  of  the  neck,  so  conspicuous  in  the  horse,  which 
that  animal  uses  as  a  fly-brusher.  The  short  muscles  are 
commonly  met  with  in  parts  where  there  is  a  limited 
extent  of  motion  and  great  power  required,  as  in  the 
movements  of  the  lower  jaw  and  the  thumb.  The  situa- 
tion of  muscles  is  either  superficial  or  deep.  The  superfi- 


THE  MUSCULAR  TISSUE.  143 

cial  are  immediately  beneath  the  skin,  and  arranged  side 
by  side,  while  the  deep  surround  the  bones  and  occupy  the 
interior  of  cavities. 

The  color  of  muscles  is  red,  varying  in  intensity  in  dif- 
ferent muscles,  and  in  different  individuals.  The  red  color, 
however,  only«applies  to  the  voluntary  muscles;  for  the 
involuntary,  as  those  of  the  intestinal  tube,  bladder,  &c., 
are  exceedingly  pale,  and,  in  some  of  the  lower  animals,  the 
whole  muscular  system  is  completely  colorless.  The  color 
is  thought  to  be  independent  of  the  blood  circulating  in 
their  vessels;  and  the  bright  red  of  those  muscles  subject 
to  the  control  of  the  will,  is  an  invariable  evidence  of  both 
vigor  and  activity. 

The  consistence  of  muscles  varies  in  different  individuals, 
and  in  the  same  individual  at  different  times,  according 
as  the  system  is  healthy  or  diseased.  In  some  they  are 
soft  and  easily  torn;  in  others  they  are  not  only  firm 
and  resisting,  but  for  some  time  after  death  remain  rigid. 
Their  size  also  varies,  from  the  extremely  delicate  mus^ 
cles  of  the  face,  to  the  powerful  glutens  maximus  of  the 
hip.  The  course  or  direction  of  muscles  is  essential  to  a 
correct  knowledge  of  their  several  actions,  and  of  the 
proper  method  of  reducing  dislocations.  Every  muscle 
has  an  axis  or  middle  line,  in  which  its  fibres  centre  or 
take  effect,  and  should,  says  M.  Cruveilhier,  be  studied 
with  special  reference  to  the  axis  of  the  limb,  or  lever  of 
which  they  are  the  moving  power. 

The  number  of  muscles  varies  in  different  animals,  and  in 
proportion  to  the  variety,  and  the  extent  of  motion,  each 
has  to  perform.  The  number  in  man  is  not  agreed  upon 
by  anatomists.  Prof.  Chausier  makes  368,  Paxton  52T, 
w.hile  others  make  450 ;  400  is  considered  a  fair  average 
number.  The  cause  of  this  disagreement  is  owing  to  the 
fact  that  some  muscles  are  divided  into  two  or  more,  while 
others  think  they  should  be  considered  but  as  one. 

The  names  given  to  muscles,  are  derived  from  a  variety 
of  circumstances,  as  their  uses,  attachment,  direction,  figure, 
composition,  size,  &c.  Examples  of  names  from  uses  may 


144 


THE  MUSCULAR  TISSUE. 


be  found  in  the  flexors,  extensors,  and  rotators  of  the  limbs; 
from  attachment  in  the  muscles,  connected  with  the  styloid 
process  of  the  temporal  bone,  the  hyoid  bone,  the  tongue, 
and  pharynx,  and  named  the  stylo-hyoideus,  stylo-glossus, 
and  stylo-pharyngeus;  from  direction  in  the  straight  mus- 
cles of  the  thigh,  the  oblique  of  the  neck,  and  transverse 
of  the  abdomen  and  perineum;  how  figure  in  the  rhomboi- 
dei  or  four-sided  muscles  of  the  back,  and  the  scaleni  or 
unequal-sided  triangular  muscles  of  the  neck ;  from  compo- 
sition in  the  biceps,  triceps,  perforans,  &c.,  as  they  are 
composed  of  two  heads,  three  heads,  or  are  perforated. 

The  attachment  of  muscles  is  various.  They  are  at- 
tached to  the  skin,  as  in  the  platysma  myoides  of  the  neck, 
to  other  muscles  as  in  the  angles  of  the  mouth,  to  cartila- 
ges as  in  the  chest  and  larynx,  to  aponeuroses,  to  tendons, 
and  through  these  to  the  periosteum  and  bones.  The  at- 
tachment of  muscles  to  the  most  fixed  point  is  called  their 
origin,  while  that  to  the  most  movable  is  regarded  as  their 
insertion. 

The  structure  of  muscles  consists  of  bundles  of  fibres 
called  fasciculi,  enclosed  in  a  cellular  membrane  or  sheath. 
Each  fasciculus  is  composed  of  still  smaller  bundles,  and 
these  again  of  single  and  more  minute  filaments;  and  here 
the  microscope  is  brought  FIG.  26. 

in  to  determine  what  is 
called  the  ultimate  fibre. 
(Fig.  26.) 

This  ultimate  fibre  is 
found  to  consist  of  a  num- 
ber of  still  smaller  fibres 
called  the  ultimate  fibrils, 
which  are  enclosed  in  a 
very  delicate  sheath  termed  the  myolemma  or  sar co-lemma. 

FIG.  26  represents  the  Muscular  Fibre  of  animal  and  organic  life — a  mus- 
cular fibre  of  animal  life  enclosed  in  its  sheath,  the  myolemma,  and  showing 
the  transverse  striae ;  fe  Ultimate  fibril  of  the  same  ;  c  A  more  highly  mag- 
nified Tiew  of  Fig.  a ;  d  Muscular  fibre  of  organic  life,  from  the  urinary  blad- 
der, magnified  600  diameters ;  e  Muscular  fibre  of  organic  life,  from  the 
stomach. 


THE  MUSCULAR  TISSUE.  145 

This  sheath  is  considered  quite  distinct  from  the  cellular 
tissue  surrounding  a  fasciculus  of  fibres,  and  is  perfectly 
transparent 

The  microscope  reveals  t^wo  kinds  of  ultimate  fibres, 
one  belonging  to  the  muscular  system  of  animal  life,  or 
voluntary  muscles,  the  other  to  that  of  organic  life  or  the 
involuntary  class.  The  fibre  of  animal  life  is  known  by 
being  marked  with  transverse  striae,  by  having  the  fibril- 
lae  beaded  or  knotted,  and  presenting  a  varicose  appear- 
ance. The  fibre  of  organic  life  has  no  transverse  striae, 
and  is  much  smaller  than  the  fibre  of  animal  life.  It  pre- 
sents swellings  at  different  points,  and  this  is  considered 
as  one  of  its  most  prominent  characteristics.  The  form  of 
the  ultimate  fibre,  according  to  Mr.  Bowman,  is  polygonal. 

When  the  fibrils  are  separately  examined,  they  are  found 
to  present  spaces  of  alternate  dark  and  light  color.  The 
size  of  these  ultimate  fibrils,  according  to  Wagner,  is  nearly 
the  same  in  all  the  vertebrata,  from  the  1-8856  to  1-11076 
of  an  inch  in  diameter.  The  diameter  of  the  primitive  fas- 
ciculi is  stated  to  be  very  variable  in  the  different  classes 
and  genera,  and  even  in  the  same  animal  and  same  muscle. 

The  size  is  greater  in  the  male  than  in  the  female,  the 
average  diameter,  as  given  by  Mr.  Bowman,  is  about  1-400. 
The  microscopic  observations  of  Mr.  Bowman  also  show  that 
there  exist  in  the  substance  of  the  ultimate  fibre,  small 
discs,  either  circular  or  oval,  frequently  concave  on  one 
or  both  surfaces,  and  having,  near  the  centre,  one,  two, 
or  three  minute  granules  or  dots.  These  are  found  to  be 
connected  with,  and  distributed  in  nearly  equal  numbers 
between,  the  fibrils ;  and  these  granules  or  corpuscles  are 
regarded  as  the  nuclei,  which  being  developed  into  the 
nucleated  cell,  constitute  the  origin  whence  the  muscular 
fibre  is  formed.  The  corpuscles  can  be  seen  by  treating 
muscle  with  some  of  the  milder  acids,  as  the  citric.  Blood 
vessels  and  nerves  enter  abundantly  into  the  structure  of 
muscles.  Muscles  possess  the  vital  property  of  contractility, 
by  which  they  can  contract  and  shorten  themselves,  and 
which,  as  already  stated,  they  take  part  in  a  great  variety 
10 


146  THE  MUSCULAR  TISSUE. 

of  functions,  and  form  the  especial  and  active  agent  in 
locomotion. 

Fibrin  is  the  chemical  element  constituting  the  great 
mass  of  muscle,  and  peculiarly  adapted  to  contraction. 
The  chemical  composition  of  muscle  is  thus  given  by  Ber- 
zelius  : 

Water,  TY.lf  Alcohol,  ext  with  salts,  1.80 

Fibrin,  15.80  Watery,  .  fV  1.05 

Albumen  with  color-  Phosphate  of  lime  with 

ing  matter,  2.20  albumen,  0.08 

The  different  varieties  of  muscular  contraction  are  those 
of  force  or  intensity,  duration,  velocity,  and  extent ;  and 
examples  of  each  variety  may  be  seen  in  the  several  mus- 
cles of  the  human  body.  The  most  rapid  movements,  ac- 
cording to  Haller,  are  to  be  found  in  the  muscles  of  the 
voice,  since  the  pronunciation  of  a  single  letter  can  be  exe- 
cuted in  the  1-3000  part  of  a  minute. 

From  experiments  on  the  bodies  of  executed  crimi- 
nals, Mr.  Nysten  found  that  the  muscles  lost  their  contrac- 
tility in  the  following  order — first,  the  left  ventricle  of  the 
heart,  next  the  intestinal  canal  in  45  or  55  minutes,  the 
urinary  bladder  in  nearly  the  same  time;  in  one  hour  the 
right  ventricle,  in  one  hour  and  a  half  the  oesophagus,  the 
voluntary  muscles  a  little  later,  and  the  last  of  all,  the  au- 
ricles of  the  heart,  particularly  the  right,  which,  it  is  said, 
Tinder  the  influence  of  galvanism,  contracted  16J  hours  after 
death.  Muscles  also  have  sensibility,  and  are  further  en- 
dowed with  an  especial  sense,  called  the  muscular  sense,  by 
which  the  precise  state  of  the  muscles  is  made  known. 

The  development  of  the  muscular  system  takes  place  from 
the  germinal  membrane,  which  is  made  to  consist  of  three 
layers,  an  external  or  serous,  an  internal  or  mucous,  and 
a  middle  or  vascular.  The  voluntary  muscles  or  those  of 
animal  life,  found  in  the  trunk  and  limbs,  are  developed 
from  the  serous  layer,  while  the  involuntary  or  those  of 
organic  life,  comprising  the  intestines,  bladder  and  inter- 
nal organs  of  generation,  are  developed  from  the  mucous. 


TENDONS. 

The  vascular  layer  develops  the  heart,  which,  though  in- 
voluntary, is  found  to  contain  the  transverse  striae  of  the 
muscles  of  animal  life. 

Tendons. — Tendons  form  the  extremities  of  muscles,  as  a 
general  rule,  though  we  sometimes  find  them,  as  in  digas- 
tric muscles,  occupying  the  centre. 

FIG.  27.  They  are  easily  distinguished  by 

their  beautifully  white  and  shining 
,  appearance,  and  though  seemingly 
continuous  with  the  muscular  fibre, 
and  at  one  time  considered  as  such, 
yet  by  maceration  and  boiling  they 
can  be  separated.  The  structure  of 
tendon  is  cellular,  condensed,  and 
modified  into  the  funicular  or  cord- 
like,  and  the  membraniform  shape- 
Its  chemical  element  is  gelatin. 
Its  fibres  run  longitudinally,,  being 
connected  by  lateral  fibrils,  and  ad- 
hering with  the  greatest  tenacity  to 
muscle.  They  have  so  little  ex- 
tensibility, that  it  is  believed  they 
will  break  sooner  than  stretch. 
They  have  no  contractility,  nor 
elasticity.  Their  sensibility  in  the 
healthy  state  is  obscure,  while  in 
the  diseased  it  becomes  very  evident.  In  health,  tendons 
have  no  red  blood  circulating  in  them,  while  in  inflamma- 
tion the  red  globules  become  very  manifest.  No  nerves 
can  be  traced  passing  into  this  tissue. 

FIG.  27  represents  the  attachment  of  tendon  to  muscular  fibre. 


148  THE  FIBROUS  TISSUE. 

-a 

CHAPTER  VIII. 

THE    FIBROUS    TISSUE.' 

ANALYSIS. 

3YNONYMES,  DEFINITION,   DIVISION,    FORM,   PROPERTIES,  STRUCTURE,  FUNCTIONS, 
AND    RELATIONS. 

THE  fibrous  tissue  lias  received  the  several  names  of  albu- 
gineous,  tendinous,  aponeurotic,  ligamentous  and  dermoid 
tissue.  It  comprises  an  assemblage  of  organs,  having 
various  forms,  serving  different  purposes,  but  all  having 
the  common  character  of  being  composed  of  distinct  fibres, 
both  firm  and  strong.  Its  principal  divisions  are, 

1.  Ligament. 

2.  Tendon. 

3.  Fibrous  envelopes,  &c. 

4.  Fibro  cartilaginous  bodies. 

These  several  varieties  do  not  form  one  continuous  and 
connected  whole,  though  Bichat  and  others  have  endeav- 
ored to  fix  a  common  centre.  Bichat  takes  the  periosteum 
as  this  centre,  others  the  membranes  of  the  brain,  and  others 
the  aponeuroses. 

The  fibrous  system  is  distinguished  by  its  brilliant  white 
color,  great  strength,  so  great  as  to  have  resisted  effectu- 
ally horse  power,  when  applied  to  the  extremities.  It  has 
little  extensibility,  breaking  before  it  will  stretch,  very  lit- 
tle elasticity,  but  is  endowed  with  great  flexibility,  and 
resists  putrefaction  for  a  long  time. 

By  desiccation  it  becomes  "somewhat  elastic,  transparent, 
of  a  yellowish  red  color,  and  almost  homogeneous,  but  by 
submitting  it  to  the  action  of  water,  it  recovers  all  its 
original  characters."  .  v  " 

Boiling  reduces  it  to  a  soft,  gelatinous  condition,  though 
at  first,  it  is  said,  contracting  it  and  making  it  more  solid 
and  elastic.  The  mineral  acids  reduce  it  to  a  pulpy  state, 
and  if  concentrated,  entirely  dissolve  it.  Alkalies,  it  is 
said,  loosen  its  texture,  separate  its  fibres,  and  cause  them 
to  assume  a  diversity  of  colors. 


THE  FIBROUS  TISSUE.  149 

FIG.  2& 


The  structure  of  this  tissue  is  essentially  fibrous,  that 
is,  it  consists  of  threads  or  fibres  variously  arranged  in  its 
different  divisions;  some  being  parallel,  some  wavy,  some 
crossed,  others  mixed,  and  some  so  very  compact  as  to 
appear  homogeneous. 

In  the  fibrous  tissue  are  distinguished  two  kinds  of  fibres, 
the  white  and  yellow.  The  white  (Fig.  28,  A,)  is  described 
as  presenting  the  form  of  "  inelastic  bands,"  of  variable 
size,  wavy  in  their  direction,  having  numerous  streaks  lon- 
gitudinally. It  is  reduced  to  gelatin  by  boiling,  and,  un- 
der the  action  of  acetic  acid,  is  seen  by  the  microscope  to 
swell  up,  become  transparent,  and  exhibit  oval  corpuscles, 
which  latter  are  believed  to  be  the  formative  nuclei  of 
this  element.  This  white  fibre  is  very  abundant  in  tendons, 
ligaments,  fibrous  membranes,  aponeuroses,  &c. 

The  yellow  fibre  (Fig.  28,  B,)  presents  the  form  of  a  cylin- 
der; readily  separates  from  its  fellows  in  the  longitudinal 
direction;  breaks  abruptly  and  curls  upon  itself,  as  seen  in 
the  figure,  and  differs  from  the  white,  in  that  boiling  has 
little  or  no  effect  upon  it.  Its  elasticity  is  said  to  be  pre- 
served for  an  almost  unlimited  period.  From  acetic  acid 
having  no  effect  upon  it,  it  can  always  be  distinguished 
from  the  white  tissue.  Various  opinions  have  been  enter- 
tained in  reference  to  the  ultimate  structure  of  these  fibres. 
Mascagni  believed  they  were  absorbent  vessels,  surrounded 

FIG.  28.  A  represents  the  white  fibrous  tissue  from  ligament,  magnified  65 
diameters.  B  shows  the  yellow  fibrous  tissue  from  the  ligamentum  nuchte. 


150  -.7       LIGAMENTS. 

by  a  vascular  web.  Beclard  considers  them  as  condensed 
cellular  tissue,  since  maceration  softens  and  reduces  them 
to  this  structure.  Isenflam  supposes  them  to  be  cellular 
filaments,  containing  gluten  and  albumen;  while  M.  Chaus- 
isier  thinks  they  are  primitive  and  peculiar.  The  microscope 
lias  measured  the  ultimate  filaments  into  which  the  fas- 
ciculi are  capable  of  being  resolved,  and  determined  it  to  be 
from  the  1-30,000  to  the  1-10,000  of  an  inch.  The  vital 
properties  of  the  fibrous  tissue,  in  the  healthy  state,  are 
very  obscure.  It  then  evinces  little  or  no  sensibility,  while 
in  inflammation  it  is  susceptible  of  the  most  acute  pain, 
Its  power  of  repair  when  injured  or  lost  is  considered  to 
be  very  great. 

In  the  embryo,  this  tissue,  like  all  other  parts,  is  soft 
and  mucus-like  in  its  appearance.  It  is  distinguished 
about  three  months  after  impregnation.  In  the  infant  it 
presents  a  pearly  white  appearance,  is  more  extensible  than 
in  the  adult,  yields  more  readily  and  is  less  liable  to  break, 
The  common  functions  of  the  fibrous  system  are  mechanical, 
and  will  be  noticed  more  particularly  under  its  several 
divisions,  which  we  shall  now  take  up  separately. 

LIGAMENTS. 

Sydesmology  (awSeaftos,  a  ligament,  xoyoj,  discourse,)  is  the 
term  applied  to  the  study  of  the  ligaments.  Ligament 
(from  ligare,  to  bind,)  is  so  called  because  it  ties  the  several 
bones  together  in  the  skeleton;  the  connection  between  any 
two  constituting  a  joint,  or  articulation.  Ligaments  most 
distinctly  represent  the  true  character  of  the  fibrous  sys- 
tem. They  are  mostly  situated  at  the  extremities  of  all 
bones  forming  joints.  Unfortunately,  this  term  has  also 
been  applied  to  an  entirely  different  structure,  as  to  the  se- 
rous membrane  of  the  abdomen,  whose  reflections  upon  the 
liver,  uterus,  &c.,  are  called  the  ligaments  of  these  or- 
gans, simply  from  the  fact  of  their  keeping  these  parts 
in  their  natural  positions,  and  not  at  all  from  the  serous 
membrane  being  supposed  to  have  any  really  fibrous  struc- 
ture. The  ligaments  are  very  numerous,  and  get  their 


LIGAMENTS.  151 

names  from  a  variety  of  circumstances,  as  from  situa- 
tion, use,  attachment,  direction,  resemblance  to  certain 
things,  &c.  Examples  of  situation  are  seen  in  the  lat- 
eral ligaments;  of  use,  in  the  capsular;  of  attachment, 
in  the  sacro-sciatic;  of  direction,  in  the  crucial;  and  of 
resemblance,  in  the  coracoid,  trapezoid,  &c. 

Ligaments  may  be  arranged,  according  to  the  motion  of 
the  part  in  which  they  are  found,  into  three  divisions : 

1.  Articular,  2.  Non-articular,          3.  Mixed. 

All  these  divisions  have  their  fibres  arranged  in  such  a 
way  as  to  assume  one  of  two  forms — either  that  of  bundles, 
called  the  funicular,  or  that  of  membrane,  the  membrani- 
form. 

The  articular  ligaments  are  the  most  important;  they 
belong  to  the  different  joints,  tie  together  different  bones, 
where  there  is  motion,  and  present  both  the  funicular  and 
membranous  forms,  as  seen  in  the  humeral  and  femoral 
articulation.  Here  the  membrane  is  called  the  capsular 
ligament,  which  is  a  sheath  surrounding  the  articulating 
bones,  binding  them  together,  and  having  its  inner  surface 
lined  by  synovial  membrane.  The  funicular  ligament  has 
its  fibres  collected  in  a  rope  or  cord,  which  may  be  internal 
to  the  capsule,  as  the  ligamentum  teres  of  the  thigh  joint, 
or  external,  as  the  lateral  ligaments  of  other  joints.  All 
these  ligaments  have  one  of  their  faces  corresponding  with 
the  synovial  membrane,  the  other  to  the  surrounding  cel- 
lular tissue,  except  those  within  the  capsule,  which  have 
an  entire  covering  of  synovial  membrane. 

The  non-articular  ligaments  are  attached  to  different 
parts  of  the  same  bone,  where  there  is  no  motion.  They 
close  notches,  for  the  transmission  of  vessels  and  nerves,  as 
the  supra-orbital,  or  shut  up  foramina,  for  the  attachment 
of  muscles,  as  the  obturator.  Those  closing  notches  are 
funicular;  those  shutting  foramina  are  membranous;  and 
both  are  without  a  synovial  membrane. 

The  mixed  ligaments  partake  of  the  characters  of  the  other 
two,  in  belonging  to  different  bones,  like  the  articular,  and 


152  ARTICULATION. 

being  destitute  of  a  synovial  membrane,  like  the  non- 
articular.  These  are  found  in  the  interosseous  spaces;  and 
the  sacro-sciatic  ligaments  belong  to  this  class.  Besides 
ligament,  there  are  other  elements  entering  into  the  con- 
stitution of  joints,  as  bone,  cartilage,  fibro-cartilage,  and 
synovial  membrane.  Each  of  these  will  be  noticed  in  its 
proper  place. 

The  different  forms  of  articulation  are  arranged  in  three 
classes : 

1.  Diarthrosis,     2.  Synarthrosis,     3.  Amphiarthrosis. 

Diarthrosis  (&a,  through,  apfyoi',  a  joint,)  is  a  movable 
articulation,  and  constitutes  the  great  number  of  the  joints. 
There  are  three  varieties  of  this  articulation,  according  to 
the  degree  of  motion — enarthrosis,  arthrodia,  and  ging- 
lymus. 

Enarthrosis  (sv,  in,  opflpov,  a  joint,)  has  the  greatest  range 
of  motion  of  all  the  joints;  it  is  called  the  ball  and  socket- 
joint,  from  the  form  of  the  bones,  and  the  manner  of  their 
connection,  as  the  hip  and  shoulder.  Arthrodia  is  an  artic- 
ulation having  a  more  limited  range  of  motion,  as  the 
clavicle,  ribs,  articular  processes  of  the  vertebrae,  radius  and 
ulna,  carpus,  tarsus,  &c.  Ginglymus  (rtyy^oj,  a  hinge,)  is  a 
hinge-like  joint,  where  the  motion  is  backwards  and  for- 
wardS;  flexion  and  extension,  as  seen  at  the  elbow,  knee,  and 
ankle.  A  variety  of  the  hinge-joint,  called  the  rotatory,  is 
fbund  between  the  radius  and  ulna.  The  synarthrosis  (ow, 
together,  apflpov,  a  joint,)  is  the  articulation  without  motion, 
where  the  bones  are  immovably  connected  together.  There 
are  four  varieties  of  this  joint : 

1.  TheSutura.  3.    Schindylesis. 

2.  Harmonia.  4.     Gomphosis. 

The  suture  has  several  varieties;  it  is  serrated  when  the 
.bones  come  together  and  interlock,  by  processes  at  their 
margins,  resembling  the  teeth  of  a  saw,  as  in  the  coronal, 
.sagittal,  and  lambdoidal  sutures  of  the  cranium.  It  is  called 
-squamous  (squama,  a  scale,)  when  the  bones  overlap,  as 
the  temporal  and  parietal  at  the  side  of  the  head.  Har- 
monia, (op«,  to  adapt,)  is  a  species  of  suture,  where  the  con- 


TENDONS.  153 

tiguous  surfaces  of  bones  come  together,  by  rather  a  smooth 
surface  and  without  any  serration,  as  in  the  nasal,  superior 
maxillary,  and  palate  bones.  Schindylesis  (40*8*4**  a  fis- 
sure,) is  also  a  variety  of  suture,  and  consists  of  a  fissure  or 
gutter,  by  which  one  bone  is  received  into  another,  as  the 
vomer,  the  sphenoid,  and  ethmoid.  Gomphosis  (70^05,  a 
nail,)  is  that  species  of  articulation  where  the  bone  is  fitted 
to  another,  after  the  manner  of  a  nail  that  is  driven  in  a 
board.  The  teeth  are  specimens  of  this  variety.  Am- 
phiarthrosis,  (a^c,  both,  aP9ov,  articulation,)  as  its  name 
implies,  partakes  of  the  character  of  both  the  diarthrosis 
and  synarthrosis;  that  is,  it  has  a  little  of  the  motion  of 
the  former,  and,  like  'the  latter,  is  without  synovial  mem- 
brane, as  in  the  bones  of  the  vertebrae. 

The  union  of  the  scapula,  or  shoulder-blade,  to  the  trunk, 
by  means  of  muscle,  called  syssarcosis,  (<nw,  together,  <yopi, 
flesh,)  and  symphysis,  as  in  the  symphysis  pubis,  sacro-iliac 
symphysis,  &c.,  are  also  considered  as  belonging  to  this 
form  of  articulation.  The  motions  of  joints  are  reduced 
to  four  varieties — the  angular  motion,  circumduction,  rota- 
tion, and  gliding.  Angular  motion  comprises  flexion,  ex- 
tension, adduction,  and  abduction.  Circumduction  is  the 
small  amount  of  motion  which  the  head  of  the .  humerus 
and  femur  make  with  their  articular  cavities,  when  their 
extremities  move  in  a  large  circle.  Eolation  is  the  mo- 
tion which  a  bone  describes  upon  its  own  axis,  as  illus- 
trated in  the  movements  of  the  radius  upon  the  humerus, 
or  the  atlas  upon  the  dentata.  The  gliding  motion  is  found 
in  the  carpus  and  tarsus,  and,  in  some  degree,  in  all  the 
joints,  and  is  the  simple  movement  of  one  articular  surface 
upon  another. 

TENDONS. 

The  tendons  have  been  already  noticed  under  the  head 
of  the  muscular  tissue,  and  we  will  here  only  speak  of  the 
points  in  which  they  differ  from  ligaments.  They  differ 
in  color — ligaments  rather  inclining  to  yellow,  while  ten- 
dons are  pearly  white.  They  differ  in  function — ligaments 


154  FIBROUS  ENVELOPES. 

simply  tying  bones  together,  while  tendons  are  princi- 
pally conductors  of  muscular  power;  and,  lastly,  they  differ 
in  their  diseases — ligaments  often  suffering  rupture  and 
inflammation,  tendons  seldom. 

The  third  division  of  the  fibrous  system  is  the 

FIBROUS    ENVELOPES. 

There  are  several  varieties  of  the  fibrous  envelope : 

1.  The  Aponeurosis,  or  fibrous  envelope  of  muscles. 

2.  The  Sheaths  of  Tendons. 

3.  Periosteum. 

4.  Perichondrium. 

5.  Fibrous  Envelopes  of  Brain  and  Nervous  System. 

6.  Fibrous  Capsules  of  other  organs. 
*T.  Compound  Fibrous  Membranes. 

The  aponeuroses,  covering  muscles,  are  called  fasciae,  as 
the  fascia-lata  of  the  thigh,  the  fascia  of  the  leg,  arm, 
&c.  In  these  cases  the  aponeurosis  completely  surrounds, 
and  sends  partitions  between,  the  different  muscles,  down 
to  the  bones,  thus  forming  an  investment  which  keeps  the 
muscles  in  their  proper  places,  and  thereby  facilitates  their 
actions.  Aponeuroses  are,  in  some  instances,  more  partial, 
and  cover  but  one  surface,  as  the  temporal  fascia,  or  are 
situated  simply  between  two  portions  of  a  muscle,  as  the 
occipito-frontalis  of  the  head.  They  also  give  insertion  to 
muscles,  as  the  tensor  vaginae  of  the  thigh.  The  aponeuro- 
ses are  nearly  as  white  and  brilliant  as  the  tendons;  their 
fibres  are  thought  to  be  more  inflexible  arid  resisting,  and 
yielding  less  readily  to  maceration  and  boiling.  Their 
density  seems  to  be  in  proportion  to  the  power,  magnitude, 
and  number  of  the  muscles  they  bind  down;  the  sheaths 
of  tendons  are  general  or  partial;  and  assume  the  form  of 
canals  and  rings — instances  of  which  are  best  seen  in 
the  hands  and  feet.  Here  the  vaginal  ligaments  are  the 
sheaths,  which,  being  attached  to  the  bones  of  the  fingers 
and  toes  their  whole  length,  form  the  canals  in  which  the 
tendons  play,  while  those  at  the  wrist  and  ancle,  surround- 
ing the  tendons  like  rings,  are  the  annular  ligaments. 


FIBROUS  ENVELOPES.  155 

The  periosteum  covers  the  bones,  and  is  commensurate 
in  extent  with  the  osseous  system,  enveloping  every  part 
of  it  except  its  articular  surfaces.  In  infancy  it  is  thick, 
and  easily  separated,  while  in  the  adult  it  is  more  com- 
pact and  adheres  strongly  to  the  hones,  sending  processes 
into  their  substance.  The  periosteum  protects  the  bones, 
conducts  the  vessels  into  their  structure,  connects  the 
epiphysis  with  the  general  shaft  of  the  bone,  during  infan- 
cy, and  gives  insertion  to  ligaments  and  muscles.  It  is 
restored  when  injured  or  destroyed. 

The  perichondrium  is  the  periosteum  of  the  non-articular 
cartilages,  and  has  the  same  properties  and  uses. 

The  fibrous-envelope  of  the  brain  and  nervous  system 
is  the  dura  mater,  which  lines  the  whole  interior  sur- 
face of  the  cranium,  sending  down  prolongations  into  the 
brain,  which  divides  it  into  several  parts,  and  passing 
into  the  vertebral  canal  to  surround  the  spinal  marrow 
and  the  nerves.  Several  other  organs  have  fibrous  capsules  ; 
thus  the  eye  has  its  sclerotica,  the  testicle  its  tunica  albu- 
ginea,  and  the  kidneys,  liver,  and  ovaries  their  special 
fibrous  envelopes. 

There  is  another  class,  called  the  compound  fibrous  mem- 
brane, which  consists  of  serous  or  mucous  membrane, 
associated  with  the  fibrous,  as  the  pericardium  and  tunica- 
vaginalis,  which  are  fibro-serous ;  and  the  larynx  and 
trachea,  which  are  fibro-mucous. 

The  yellow  elastic  fibrous  system  derives  its  name  from 
the  yellowness  of  its  color  and  the  elasticity  of  its  fibre.  It 
is  found  in  those  parts  where  there  is  much  resistance  to 
overcome.  The  yellow  ligaments  of  the  vertebne  are  of 
this  class.  The  elastic  coat  of  the  arteries,  of  the  excretory 
ducts,  the  coverings  of  the  spleen,  and  corpora  cavernosa, 
are  also  viewed  as  belonging  to  this  division.  It  has  less 
tenacity,  but  more  extensibility,  than  the  other  fibrous  tis- 
sues. -Its  chief  physical  property,  however,  is  elasticity, 
which  it  possesses  in  consequence  of  the  water  it  contains, 
for,  when  deprived  of  its  water,  it  loses  this  property,  and, 
when  this  is  restored  to  it,  it  again  recovers. 


156  THE  CARTILAGINOUS  TISSUE. 

The  relations  of  the  fibrous  system  are  numerous  and  im- 
portant. We  have  seen  it  related  with  the  osseous  system, 
without  which  connection  the  skeleton  would  tumble  to 
pieces,  and  the  form,  size,  strength,  and  flexibility  of  the 
body  consequently  be  lost.  We  find  it  attached  to  mus- 
cles, without  which  their  properties  of  contraction  could  be 
exercised  wTith  but  little  advantage.  We  see  it  entering 
into  the  organs  of  respiration,  where,  if  absent,  air  could 
not  reach  the  lungs,  and,  consequently,  the  vital  change  of 
venous  into  arterial  blood  could  not  take  place.  And  we 
also  find  the  fibrous  system  connected  with  the  brain  and 
nervous  system,  the  liver,  the  spleen,  the  kidneys;  in  a 
word,  there  is  no  organ  or  function  with  which  it  is  not 
more  or  less  intimately  associated,  and  without  it  the 
whole  machinery  of  life  would  stop. 


CHAPTER  IX. 

THE  CARTILAGINOUS    TISSUE. 

ANALYSIS. 
DEFINITION,   DIVISION,    FORM,    PROPERTIES,    STRUCTURE,    FUNCTIONS,    RELATIONS. 

THE  cartilaginous  tissue  is  readily  known  by  its  superior 
elasticity,  its  great  hardness,  only  second  to  that  of  the  bones, 
and  by  its  whiteness  and  flexibility.  It  subserves  the  pur- 
pose of  skeleton  in  some  of  the  inferior  animals,  being  the 
only  substitute  they  have  for  bone.  Cartilages  are  divided 
into  the  temporary  and  permanent;  the  former  regularly 
disappearing  at  a  determinate  period  of  their  growth,  when 
they  ossify  and  form  the  bones,  the  latter  remaining  as  per- 
manent cartilages  during  life,  as  in  the  ribs,  larynx,  &c. 
The  permanent  cartilages  are  divided  into  the  articular, 
or  those  which  have  no  perichondrium,  such  as  are  seen  in 
the  various  joints,  and  into  those  which  have  this  fibrous 
covering,  as  the  cartilages  of  the  ribs  and  ear. 

This  tissue  has  a  variety  of  /orm,  some  of  the  cartilages 
being  long  and  narrow,  others  thin  and  broad,  and  all 


THE  CARTILAGINOUS  TISSUE.  157 

more  or  less  flattened.  Boiling,  at  first,  crisps,  but  con- 
tinued, reduces  cartilage  to  jelly.  This  is  said  to  be 
true  only  of  the  articular  cartilages,  the  others,  having  lit- 
tle or  no  gelatin,  are  not  dissolved.  Drying  makes  this 
tissue  appear  of  a  semi-transparent  yellow  color,  dimin- 
ishes its  bulk,  and  destroys  its  elasticity.  Cartilage  con- 
tains a  great  quantity  of  water,  upon  which  depends  its 
properties  of  color,  flexibility,  volume,  and  elasticity,  and 
which,  when  impaired  or  lost,  may  be  recovered  by  restor- 
ing the  water.  Alcohol  renders  this  tissue  slightly  opaque; 
acids,  concentrated,  dissolve  it.  Chemical  analysis  makes 
cartilage  to  consist  of  gelatin  44.5,  phosphate  of  lime  0.5, 
water  55.  Maceration  and  putrefaction  are  resisted  for  a 
longer  time  by  this  tissue  than  any  other,  except  bone. 

The  structure  of  cartilage  appears  to  be  homogeneous, 
presenting,  according  to  M.  Beclard,  neither  "  cavities  nor 
canals,  nor  areolas,  nor  fibres,  nor  Iamina3,  nor  blood  ves- 
sels, nor  absorbents,  nor  nerves;"  in  a  word,  they  seem  to 
be  destitute  of  every  thing  like  organization.  It  is  never- 
theless certain  there  must  be  a  species  of  circulation  an- 
swering, at  least,  their  mode  of  existence,  as  is  evident  in 
cases  of  jaundice,  when  these  parts  are  deeply  tinged  with 
the  yellow  coloring  matter  of  the  bile,  and  in  ossification 
of  this  tissue  the  bony  matter  is  deposited  in  the  centre  of 
the  cartilage,  which  could  only  be  done  by  the  circulation. 
Mr.  Bayle  remarks  that  although  the  cartilaginous  tissue, 
at  first  sight,  appears  homogeneous,  yet,  on  minute  exam- 
ination, small  fibres  may  be  discovered,"  and,  when  mace- 
rated for  a  long  time,  assumes  the  appearance  of  a  "  cellu- 
lar net-work."  In  the  embryo  cartilages  are  soft,  mucous, 
and  transparent  like  jelly  or  glue.  In  the  child  they  are 
yet  very  transparent,  soft,  and  slightly  elastic,  and  in  the 
adult  acquire  the  natural  firmness,  opacity,  and  all  the 
properties  which  especially  distinguish  them;  while  later, 
in  old  age,  they  become  more  yellow,  more  opaque,  less 
flexible,  less  elastic,  more  brittle,  dryer,  contain  less  water, 
and,  in  proportion,  more  earthy  matter.  Cartilage  springs 
from  cells  like  all  other  tissues.  These  cells  are  called 


158 


THE  CARTILAGINOUS  TISSUE. 


cartilage  corpuscles,  containing  nucleii  and  nucleoli,  situ- 
ated in  an  amorphous  substance  from  which  arises  the  cyto- 
blasts  or  germinal  particles  forming  the  cells.  The  cells 
are  found  to  vary  in  their  size,  shape,  and  number,  accord- 
ing to  the  cartilages  examined.  Those  of  the  ribs  measure 
FIG.  29.  from  1-650  to  1-430  of  an 

inch  in  diameter,  while 
in  the  cartilages  of  the 
joints  they  are  from 
1-1300  to  1-900  of  an 
inch.  Their  shape  is 
ovoidal,  round  or  lenti- 
cular and  notched.  The 
cell  cartilage  is  distin- 
guished by  a  substance 
called  chondrin,  which 
resembles  gelatin,  but 
requires  a  longer  boil- 
ing for  its  solution.  It  hardens  on  cooling,  and  looks  like 
glue.  It  is  not  precipitated  by  tannic  acid,  in  which  it 
differs  from  gelatin.  Acetic  acid,  alum,  acetate  of  lead, 
and  proto-sulphate  of  iron,  precipitate  chondrin,  but  have 
no  effect  on  gelatin.  .Cartilage  is  supposed  to  be  nourished 
by  the  agency  of  its  cell,  those  nearest  the  blood  vessels 
take  the  nutritive  materials  and  hand  it  over  to  the  next 
series,  and  those  to  the  next,  and  so  in  regular  succession 
till  the  whole  is  supplied. 

The  functions  of  cartilages  are  to  supply  the  place  of 
bone  in  some  parts,  and  to  connect  and  facilitate  their  mo- 
tions in  others.  Cartilages  are  accidentally  developed  in 
various  parts  of  the  body,  as  in  the  lungs,  arteries,  semi- 
lunar  valves,  pleurge,  coverings  of  spleen,  testicles,  ureters, 
vagina,  and  in  the  substance  of  some  organs,  as  the  ovaries, 

FIG.  29  represents  a  cylinder  of  bone  filled  with  cartilage  corpuscles ;  6  c 
represents  several  lamina  of  bone  and  unossified  cartilage  corpuscles  ;  d  rep- 
resents the  process  of  ossification  as  complete,  and  the  opening  in  the  centre 
as  the  Haversian  canal  of  the^ossicle  j  e  shows  the  interosseous  space  filled 
with  bony  matter. 


FIBRO-CARTILAGINOUS  TISSUE.  159 

and  thyroid  gland.  Cartilage  is  also  frequently  completely 
transformed  into  bone,  as  the  costal,  connecting  the  ribs 
with  the  sternum.  The  relations  of  the  cartilaginous  system 
are  very  important  and  extensive.  In  the  young  state  it 
represents  the  entire  osseous  system,  and  without  it  the 
skeleton  could  have  no  proper  existence  or  motion.  It  also 
enters  into  the  organs- of  voice  and  respiration.  Hence 
the  utility  of  this  tissue,  the  close  relationship  and  de- 
pendence of  other  tissues  upon  it,  and,  consequently,  the 
well-being  of  the  whole  ceconomy  on  its  integrity  and 
preservation. 


CHAPTER  X. 

FIBRO-CARTILAGINOUS  TISSUE. 

THIS  tissue,  as  its  name  implies,  consists  of  both  fibre 
and  cartilage,  uniting  the  tenacity  of  the  former  with  the 
density  and  elasticity  of  the  latter.  It  presents  three 
varieties. 

1.  The  membraniform  as  seen  in  the  external  ear,  alee  of 
the  nose,  cartilages  of  the  eyelids  and  the  trachea. 

2.  The  inter-articular,  found  between  the  bodies  of  the 
different  vertebrae,  at  the  clavicle,  inferior  maxillary,  and 
knee-joints. 

3.  The  trochlea  for  the  gliding  of  tendons. 

The  cotyloid  and  glenoid  ligaments,  which  deepen  the 
articular  cavities  of  the  thigh  and  shoulder  joints,  belong 
also  to  this  class. 

The  fibres  of  this  tissue  are  said  to  run  in  every  direction, 
some  parallel,  others  interlaced  and  crossed,  others  concen- 
tric, and  all  having  their  spaces  filled  with  cartilage.  Desic- 
cation makes  it  yellow  and  transparent  like  the  ligaments. 
Boiling  reduces  it  to  gelatin.  The  first  variety  only  has 
perichondrium,  the  others  adhering  to  the  bone  or  being 
covered  by  synovial  membrane. 

The  functions  of  this  system  vary  in  different  parts.    We 


160  ERECTILE  TISSUE. 

find  it  assisting  in  forming  the  organ  of  the  nose,  ear,  and 
trachea,  and  consequently  taking  part  in  the  functions  of 
respiration,  hearing  and  smelling.  By  being  placed  be- 
tween articular  surfaces,  it  prevents  concussion,  and  in  the 
trochleas,  it  facilitates  the  movement  of  tendons. 


CHAPTEK  XL 

ERECTILE   TISSUE. 

THE  corpora  cavernosa,  in  the  penis  of  the  male,  the 
clitoris  of  the  female,  the  nymphas,  the  tissues  around  the 
vaginae,  and  the  nipple  in  both  sexes,  are  all  regarded  as 
specimens  of  the  erectile  tissue. 

This  tissue,  it  is  believed,  consists  essentially  of  a  plexus 
of  varicose  veins,  surrounded  by  a  fibrous  envelope.  The 
cause  of  erection,  or  turgescence,  in  the  penis  and  clitoris, 
called  turgor-vitaliSj  has  been  ascribed  to  compression  of 
the  vena  dorsalis  against  the  symphysis  pubis,  and  to  the 
action  of  the  ischio-cavernosi  muscles.  That  such  cannot 
be  the  cause  in  all  cases,  may  be  safely  inferred  from  the 
fact  that  there  is  no  such  compression  nor  any  such  muscles 
acting  upon  the  nipple  where  this  erection  equally  occurs. 

According  to  Gerber  the  venous  plexus  is  traversed  by 
numerous  contractile  fibres,  whose  contraction  causes  ob- 
struction in  the  venous  circulation,  producing  thereby  the 
turgescence  and  erection.  Valentin  describes  a  tendinous 
tissue  between  the  anastomosing  veins,  having  muscles  at- 
tached to  it,  which  he  supposes  the  active  cause  of  the  erec- 
tion ;  but  his  reasons  for  regarding  such  structure  as  mus- 
cular, are  not  considered  conclusive.  Muller  says  the  ex- 
citing cause  is  nervous  irritation,  proceeding  from  the  brain 
and  spinal  marrow,  or  arising  in  the  part  itself,  and  that 
the  pudic  nerves  are  the  means  of  transmitting  the  nervous 
influence ;  as  from  the  experiments  of  Guenther,  it  seems 
the  penis  was  incapable  of  erection  when  these  nerves  were 
divided.  Muller  has  discovered  a  set  of  arteries  which  he 


THE  OSSEOUS  TISSUE. 


161 


calls  the  helicine,  that  penetrate  the  cavernous  substance 
and  end  abruptly  in  the  venous  cells,  which  he  regards  as 
chiefly  concerned  in  the  erection,  but  whose  existence  is 
denied  by  Valentin. 


FIG.  30. 


CHAPTER  XII. 

THE    OSSEOUS    TISSUE. 

ANALYSIS. 

DEFINITION,    COMPOSITION,    SKELETON,    DIVISIONS,    NUMBER,    SITUATION,    DENSITY, 
STRENGTH,    SURFACE,    STRUCTURE,   DEVELOPMENT,    GROWTH,    CALLUS. 

THE  ~bones  are  the  hardest  of  all  the  tissues;  they  consti- 
tute the  solid  frame-work  of  the  body,  are  the  passive  organs 
of  locomotion,  give  attachment  to  a  variety  of  muscles,  and 
afford  protection  to  numerous  viscera. 

Bone  consists  essentially  of  two 
parts,  an  earthy  and  an  animal ;  the 
earthy  being  chiefly  phosphate  of 
lime,  the  animal  mainly  gelatin.  By 
subjecting  bone  to  fire,  the  animal 
portion  is  consumed  and  the  earthy 
left ;  presenting,  however,  the  perfect 
shape  of  the  bone,  but  being  very  brit- 
tle, easily  reduced  to  powder  and  pre- 
senting the  honey-comb  appearance. 
When  put  in  dilute  muriatic  acid, 
about  1  part  of  acid  to  30  of  water, 
the  earthy  portion  is  removed  and 
the  animal  left,  which  also  retains 
the  original  shape  of  the  bone.  The  chemical  analysis  of 
bone,  according  to  Berzelius,  makes  it  consist  of — 

FIG.  30  represents  the  texture  of  bone  after  maceration  in  dilute  acid,    a  a, 
compact  matter.    6  6  The  same  split  up,  so  as  to  show  the  longitudinal  fibres 
Composing  it.  c  Internal  cellular  or  cancellated  structure,    d  Bone  seen  under 
its  articular  cartilage. 
11 


162  THE  OSSEOUS  TISSUE. 

Cartilage,  32.17    Fluoride  of  Calcium,      2.00 

Insol.  animal  matter,  1.13  Phos.  of  magnesia,  1.16 
Phosphate  of  lime,  51.04  Soda,  chlo.  of  sodium,  1.20 
Carbonate  of  lime,  11.30 

Vanquelin  and  Fourcroy  have  also  detected  iron,  man- 
ganese, silex,  alumina,  and  phosphate  of  ammonia. 

These  ingredients  are  found  in  bone  every  where,  and 
under  all  circumstances,  though  the  relative  proportion  of 
the  respective  parts  often  varies,  not  only  in  different  bones 
but  at  different  times  in  the  same  bone. 

The  bones  of  the  cranium,  especially  the  petrous  portion 
of  the  temporal,  furnish  more  calcareous  matter  than  the 
rest  of  the  bones  of  the  same  skeleton.  To  the  predomi- 
nance of  the  earthy  matter,  in  the  aged,  do  the  bones  owe 
their  great  brittleness ;  while,  on  the  contrary,  in  chil- 
dren, it  is  deficiency  of  the  earthy  and  predominance  of  the 
animal  matter,  which  make  the  bones  at  that  age  so  very 
flexible. 

The  bones  collectively  constitute  the  skeleton.  When 
they  are  united  by  their  own  ligaments,  left  for  that  pur- 
pose, the  skeleton  is  a  natural  one.  When  they  are  con- 
nected by  wire  or  any  other  foreign  substance,  it  is  artificial. 

The  skeleton  is  divided  into  the  head,  trunk  and  extrem- 
ities. The  bones  composing  these  great  divisions  are  again 
divided,  according  to  their  form,  into  the  long,  the  flat,  or 
broad,  the  short  and  the  mixed. 

Specimens  of  the  long  bones  are  found  in  the  extremities, 
as  in  the  thigh,  leg  and  arm.  The  flat  compose  the 
cranium  and  pelvis.  The  short  are  seen  in  the  wrist,  in- 
step and  spine ;  while  the  sphenoid  and  temporal  bones 
present  examples  of  the  mixed. 

The  number  of  bones  in  the  human  body  is  not  precisely 
agreed  upon  by  anatomists,  some  making  more  and  others 
less,  owing  to  the  period  of  life  at  which  the  calculation  is 
made.  The  younger  the  subject,  the  more  numerous  are 
the  bones,  and  as  age  increases,  the  bones  run  into  each 
other  and  become  fewer  in  number.  Taking  the  adult  pe- 
riod as  the  standard,  the  whole  number  may  be  estimated 


THE  OSSEOUS  TISSUE.  163 

at  211;  not  including,  however,  in  this  calculation,  the 
teeth  and  the  sesamoid  bones.  The  former  are  separated 
from  the  skeleton  for  reasons  to  be  given  hereafter,  and  the 
latter  are  regarded  as  developments  of  the  tendinous  struc- 
ture. 

The  head  has  22  bones,  1  frontal,  1  occipital,  2  parietal, 
2  temporal,  1  sphenoid,  and  1  aethmoid,  constituting  the 
cranium ;  while  the  2  superior  maxillary,  2  palatal,  2  ma- 
lar, 2  nasal,  2  lachrymal  or  unguiform,  2  inferior  turbi- 
nated,  1  vomer,  and  1  inferior  maxillary,  making  14,  form 
the  face. 

The  trunk  has  56;  24  true  or  movable  vertebrae,  1 
sacrum,  4  caudal  vertebrse  or  bones  of  the  coccyx,  2  ossa 
innominata,  12  ribs  on  each  side,  and  1  sternum. 

The  hyoid  bone  stands  by  itself,  at  the  upper  part  of  the 
neck,  and  consists  of  three,  sometimes  of  five,  pieces. 

The  superior  extremities  have  68  bones,  viz:  2  clavicles, 
2  scapulas,  2  humeri,  2  radii,  2  ulnae,  16  carpal,  10  meta- 
carpal,  and  28  phalanges,  forming  the  shoulder,  arm,  fore- 
arm and  hand,  of  both  upper  extremities. 

The  inferior  extremities  have  64  bones,  viz:  1  femur, 
1  tibia,  1  fibula,  1  patella,  7  bones  of  the  tarsus,  5  for  the 
metatarsus,  and  14  phalanges  for  each  lower  limb,  consist- 
ing of  the  thigh,  leg,  and  foot. 

The  situation  of  the  bones  is  either  superficial  or  deep. 
Examples  of  the  former  are  seen  in  the  tibia  and  clavicle, 
which,  excepting  a  little  cellular  and  adipose  structure,  are 
only  covered  by  the  skin;  while  the  latter,  as  the  thigh 
bone,  are  some  distance  from  the  surface,  and  have  a  thick 
covering  of  muscle. 

Bones  present  different  degrees  of  density,  varying  even 
in  different  parts  of  the  same  bone;  those  of  the  carpus  and 
petrous  portions  of  the  temporal  bone  presenting  specimens 
of  the  greatest  density  and  compactness,  while  the  long 
bones  have  their  bodies  or  diaphyses  compact,  and  their 
extremities  loose  or  spongy.  (Fig.  30.) 

Under  the  head  of  structure,  to  be  presently  noticed,  we 
shall  see  that  the  osseous  fibres  are  brought  either  very 


164  THE  OSSEOUS  TISSUE. 

closely  together  and  much  condensed,  or,  on  the  other  hand, 
are  more  or  less  widely  separated,  and  intersect  each  other  in 
every  direction,  so  as  to  present  the  honeycomb  appearance. 
The  first  or  condensed  state  forms  the  compact,  the  second, 
the  cellular  or  cancellated  structure,  of  bone.  The  compact 
gives  strength  and  firmness  to  bone,  and  forms  its  external 
osseous  layer;  while  the  cellular  is  delicate  and  spongy, 
and  designed  to  support  the  medullary  membrane  and  its 
marrow. 

The  strength  of  bones  varies  equally  with  their  density, 
and  that  in  different  parts  of  the  same  bone.  The  thigh 
bone,  for  instance,  is  not  of  equal  strength  in  its  whole 
length;  the  body,  having  the  compact  tissue,  is  capable 
of  resisting  a  greater  degree  of  force  than  the  extremities, 
which  have  only  the  light,  spongy  formation  of  delicate, 
reticulated  structure.  All  the  long  bones  have  a  hollow 
canal  extending  nearly  their  whole  length,  which  is  found 
to  add  greatly  to  their  strength,  at  the  same  time  increas- 
ing their  lightness.  This,  Dr.  Physick,  in  a  very  beautiful 
and  simple  manner,  illustrated  by  taking  a  sheet  of  paper 
and  rolling  it  into  scrolls  or  hollow  cylinders  of  various 
diameters.  He  found  the  power  of  sustaining  pressure  to 
increase,  in  a  precise  ratio  with  the  increase  of  diameter, 
up  to  a  certain  point.  Now,  taking  a  similar  sheet  and 
rolling  it  into  a  solid  cylinder,  and  comparing  its  strength 
with  that  of  the  hollow  one,  it  was  found  that  its  capacity 
for  sustaining  weight,  and  its  power  of  resisting  pressure, 
were  much  less. 

The  doctor,  by  an  equally  simple  experiment,  shows  that 
the  use  of  the  cellular  arrangement,  or  diploe,  between  the 
two  tables  of  the  flat  bones,  is  to  give  strength,  by  deaden- 
ing the  force  of  blows,  and,  as  in  the  cranium,  giving 
greater  security  to  the  organs  they  are  designed  to  protect. 
The  experiment  consisted  in  taking  a  certain  number  of 
ivory  balls  and  suspending  them.  When  the  first  in  the 
series  was  elevated  several  degrees  and  let  fall  against  the 
second,  the  result  was  the  elevation  of  the  last  ball  to  an 
angle  nearly  equal  to  the  first.  A  ball  made  of  the  cellu- 


THE  OSSEOUS  TISSUE.  165 

lar  structure  of  "bone  was  now  substituted  for  the  middle 
one  of  ivory,  and  the  series  submitted  to  the  same  process ; 
the  impulsive  power  of  the  first  hall  was  now  found  to  he 
almost  entirely  destroyed  on  reaching  the  last. 

All  the  hones  present  upon  their  surface  impressions 
which  are  either  regular  or  irregular,  smooth  or  rough ; 
this  diversity  depending  upon  the  projections  and  depres- 
sions every  where  belonging  to  bones.  They  constitute 
most  important  practical  points  to  the  surgeon;  as  they 
form  his  guide  in  many  operations,  while  they  also  give 
origin  and  insertion  to  muscles,  and  at  the  extremities  of 
bones  form  the  articular  surfaces  of  joints.  The  projec- 
tions from  the  surface  of  bones  are  called  apophyses  or 
processes,  (arfo,  from,  <j>i>cyiat,  to  grow,)  in  early  life  epiphy- 
ses,  (frtt,  upon,  $u<y«M,  to  grow.)  The  apophyses  are  divided 
into  those  forming  articulations,  and  those  giving  attach- 
ment to  fibrous  organs.  Cloquet  gives  the  following 
summary. 

1st.  Apophyses  forming  articulations. 

Those  belonging  to  movable  articulations. 

Heads,  which  are  nearly  hemispherical,  as  the  head  of 
the  humerus  and  femur. 

Condyles,  which  are  broader  in  one  direction  than  another, 
as  the  condyles  of  the  femur. 

Those  belonging  to  articulations  not  having  motion,  den- 
tations, or  teeth-roots,  &c. 

2d.  Apophyses  affording  attachment  to  fibrous  organs, 
and  named  according  to  their  general  forms. 

Impressions,  unequal  eminences,  not  much  raised  and 
extended  in  breadth. 

Lines,  unequal  eminences,  not  very  prominent,  but  ex- 
tended in  length,  as  the  linea-aspera. 

Ridges,  resembling  lines,  but  smooth  and  more  distinct, 
as  the  superciliary  ridge. 

Bumps,  when  they  are  rounded,  broad,  and  smooth. 

Tuberosities  and  protuberances,  when  rounded  and  rough, 
as  the  tuberosity  of  the  ischium,  the  bicipital  protuber- 
ance, &c. 


166  THE  OSSEOUS  TISSUE. 

Apophyses  named  according  to  the  bodies  to  which  they 
are  compared. 

Spines,  resembling  a  thorn,  as  the  spinous  processes  of 
the  vertebrae. 

Styloid,  in  the  form  of  a  conical  point. 

Coracoid,  like  the  beak  of  a  crow. 

Odontoid,  or  tooth-like. 

Mastoid,  like  the  nipple. 

Apophyses  named  according  to  their  uses. 

Trochanters,  or  those  subservient  to  turning,  as  the  tro- 
chanter  major,  and  minor  of  the  thigh  bone. 

Orbitary,  belonging  to  the  orbit. 

Apophyses  named  according  to  their  direction  and  rela- 
tive situation. 

Oblique,  transverse,  anterior,  &c.  The  cavities  upon  the 
surface  of  bones  have  two  divisions. 

1st.  Articular  cavities. 

2d.  Those  which  do  not  belong  to  articulation. 

The  first  division  includes  the 

Cotyloid,  (xotfrty,  cup,  c&So?,  shape,)  a  cavity  deep  and  round, 
as  seen  at  the  thigh  joint. 

Glenoid,  (ya^,  shallow,)  shallow  cavities,  like  that  at 
the  shoulder  joint. 

TrocJiliform,  when  scooped  in  the  form  of  pulleys,  as  in 
the  elbow  joint. 

Faces,  when  nearly  plane. 

Alveoli,  when  of  a  conical  form,  as  the  sockets  for  the 
teeth. 

The  second  division  includes  cavities  not  entering  into 
articulation. 

1.  Cavities  intended  for  the  reception  of  parts. 
FOSSCB,  when  the  entrance  is  wider  than  the  bottom. 
Sinuses,  when  it  is  narrower. 

2.  Cavities  for  the  insertion  of  parts. 

Impressions,  when  they  are  wide,  unequal  and  shallow 
Grooves,  when  extended  in  length. 

3.  Cavities  for  the  passage  of  tendons. 

4.  Cavities  formed  by  the  impression  of  parts. 


THE  OSSEOUS  TISSUE.  167 

Gutters  or  channels  corresponding  to  blood  vessels. 

5.  Cavities  subservient  to  transmission. 

Notches ,  when  superficial  and  formed  in  the  edges  of 
bones. 

Foramina,  when  they  pass  through  or  perforate  the  bone. 

Canals,  when  their  passage  is  of  great  extent,  as  the 
vertebral  or  medullary  canal. 

Clefts  or  Fissures,  if  they  are  longitudinal  and  narrow. 

The  structure  of  bone  consists  of  several  elements. 

By  the  naked  eye  the  fibrous  arrangement  is  observed, 
and  the  fibres,  as  already  stated,  assume  two  forms,  the  one 
forming  the  compact,  the  other  the  spongy  or  cancellated 
structure.  A  modification  of  the  spongy,  in  the  medul- 
lary cavity,  receives  the  name  of  the  reticular  tissue. 

The  compact  tissue  occupies  the  outer  surface  of  the 
bones,  and  has  its  fibres  compressed  so  as  to  form  a  com- 
pact, firm  and  dense  tissue. 

Bone,  treated  with  nitric  acid,  is  made  soft  and  its  fibrous 
character  clearly  shown.  In  the  long  bones  the  fibres  ar- 
range themselves  longitudinally ;  in  the  flat,  they  diverge 
like  radii  from  a  certain  point,  while  in  the  thick  they  are 
very  irregular.  The  osseous  fibres  are  found  to  be  lamin- 
ated as  well  as  fibrous,  that  is,  consisting  both  of  filaments 
and  plates  or  laminse ;  and  the  intervals  between  them  are 
only  seen  with  the  microscope.  These,  however,  become 
gradually  more  and  more  distinct  as  they  approach  the 
extremity  of  the  bone,  and  are  there  continuous  with  the 
cellular  or  reticulated  tissue.  Indeed,  says  Cruveilhier, 
"  the  compact  tissue  is  nothing  more  than  an  areolar  sub- 
stance, the  meshes  of  which  are  extremely  close  and  much 
elongated,"  Diseases  also  frequently  show  the  compact 
tissue  changed  into  the  spongy,  and,  vice  versa,  the  spongy 
into  the  compact 

The  spongy  or  honey-comb  structure  (Fig.  30)  pre- 
sents cells  and  areolae  of  variable  size  and  shape,  all  of 
which  communicate,  and  consist  of  filaments  and  fine 
laminae,  crossing,  uniting,  and  separating  in  every  direc- 
tion. These  cells  contain  marrow,  and  hence  are  called 


168  THE   OSSEOUS  TISSUE. 

medullary  cells.  The  cellular  structure  is  only  found  to 
exist  when  ossification  commences.  The  relative  propor- 
tion of  these  two  substances  varies  greatly  even  in  the  same 
bone ;  the  compact  predominating,  as  in  the  body  of  long 
bones,  where  strength  is  required,  while  the  spongy  pre- 
vails at  the  extremities,  where  extent  of  surface,  for  va- 
riety of  motion,  is  needed. 

The  microscope  makes  more  evident  the  laminated  con- 
dition of  bone,  and  reveals  many  other  points  in  minute 
anatomy  hitherto  unknown.  It  shows  the  laminated  struc- 
ture in  long  bones  to  FIG.  31. 
be  arranged  in  concen- 
tric circles,  while  in  the 
flat,  the  fibres  run  par- 
allel with  the  surface. 
Between  the  laminae  a 
multitude  of  longitu- 
dinal canals,  called,  af- 
ter Havers,  their  dis- 
coverer, the  Haversian  canals,  are  seen.  They  are  nar- 
row, cylindrical,  form  a  net-work,  connect  with  e-ach  other, 
and  open  externally  upon  the  periosteum,  and  internally 
connect  with  the  cellular  structure  and  medullary  cells. 
These  canals  are  fo-und  to  measure  from  1-200  to  1-2500  of 
an  inch,  and  contain  blood-vessels  and  an  oily  matter,  and 
are  supposed  to  be  simply  miniature  representations  of  the 
great  medullary  canal  itself,  having  similar  functions  of 
receiving  blood  vessels  and  containing  the  fat. 

These  Haversian  or  medullary  canals  are  seen  to  be 
surrounded  by  from  four  to  twelve  concentric  lamella  or 
osseous  plates,  intersected  or  perforated  by  minute  tubes 
called  calcigerouSy which  are  supposed  to  contain  the  earthy 
matter;  also  between  the  laminae  are  seen,  on  a  trans- 
Terse  section  of  bone,  little  cavities  called,  after  their 
discoverer,  the  corpuscles  of  Purkinje,  which  also  receive 
the  names  of  bone  corpuscles  and  lacunas.  (Fig.  32.)  These- 

FIG.  31  represents  the  concentric  lamellae  of  bone,  taken  from  a  transverse 
section  of  the  tibia,  after  maceration  in  weak  muriatic  acid. 


THE  OSSEOUS  TISSUE.  169 

cavities  contain  granular  matter,  and  have  the  calcigerous 
tubes  running  into  or  passing  from  them  in  a  stellate  form. 
There  are  also  certain  lines  or  stride  described  by  Deutsch, 
but  which  Wilson,  in  his  observations,  makes  identical 
with  the  calcigerous  tubuli. 

The  bones  have 

FIG.  32. 

two  membranes,  the 
one  covering  their 
outer  surface,  called 
the  periosteum,  the 
other  lining  the  in- 
terior of  their  cavi- 
ty, called  the  me- 
dullary membrane. 
The  periosteum  is  a 
fibrous  membrane, 
and  has  been  described  under  the  head  of  the  fibrous  sys- 
tem. It  covers  every  part  of  the  bone  except  the  articular 
surface ;  it  is  continuous,  at  the  extremities,  with  the  liga- 
ments, loosely  attached  in  infancy,  but  closely  adherent  in 
adult  bone. 

The  periosteum  is  very  vascular,  and  both  its  fibres  and 
vessels  pass  together  into  the  bone. 

The  medullary  membrane  is  an  exceedingly  delicate  mem- 
brane, composed  of  a  very  fine,  soft,  cellular  tissue,  con- 
taining numerous  minute  blood  vessels.  It  can  be  traced 
lining  the  whole  interior  of  the  medullary  cavity,  and  ex- 
tending into  the  medullary  cells,  and,,  it  is  believed,  into  all 
spongy  structure  wherever  found.  This  membrane  forms 
vesicles  for  containing  the  marrow,  which  fills  the  reticular 
spaces  in  bone.  In  birds  these  are  occupied  by  air.  Both 
it  and  the  periosteum  accompany  the  blood  vessels  through 
bone.  Besides  secreting  the  marrow,  this  membrane  serves 
to  nourish  the  bones. 

The  blood  vessels  supplying  bones  are  numerous.  The 
arteries  are  referred  to  three  classes.  1st.  Those  which 

FIG.  32  represents  a  transverse  section  of  bone  with  the  Haversian  canals 
and  lacunae. 


1*70  DEVELOPMENT  OF  BONE. 

enter  the  bone  from  the  periosteum,  by  the  numerous 
foramina  upon  its  surface.  2d.  Those  which  enter  by  the 
larger  foramina  at  the  extremities  of  the  long  bones,  and 
at  difterent  points  upon  the  surface  of  others ;  while  the 
3d,  called  nutritious  arteries,  enter  the  long  bones  by  a  sin- 
gle foramen,  and  that  near  the  centre  of  each. 

The  arteries  of  the  first  two  classes  ramify  minutely 
throughout  the  whole  of  the  compact  and  cellular  structure. 
The  nutritious  artery  is  much  larger,  and  passes  single 
through  the  compact  structure  to  the  medullary  cavity, 
where  it  divides  into  two  branches,  an  ascending  and  de- 
scending, which  ramify  upon  the  medullary  membrane  in 
countless  capillary  vessels,  and  anastomose  freely  with  the 
other  two  classes. 

The  veins  are  numerous,  those  accompanying  the  nutri- 
tious artery  pass  out  of  the  same  foramen,  and  return  the 
blood  from  the  medullary  membrane.  The  veins  which 
receive  the  blood  from  the  other  two  classes  of  arteries  do 
not  attend  them,  but  pass  out  by  numerous  distinct  open- 
ings found  upon  the  surface  of  the  bones,  and  after  a  short 
course  join  the  general  circulation. 

Lymphatics  have  been  demonstrated  in  the  medulla,  but 
not  with  certainty  in  bone. 

Nerves  have  been  traced  along  the  nutritious  arteries, 
but  not  into  the  substance  of  the  bone  itself 

DEVELOPMENT  OF  BONE. 

"  In  the  human  foetus  and  other  animals,  before  the  time 
of  birth,"  says  John  Bell,  "  instead  of  bones  there  are  only 
cartilages  of  the  form  of  the  future  bone.  The  whole 
foetus  appears  to  the  eye  like  a  mere  jelly.  The  bones  are 
a  pure,  almost  transparent  and  tremulous  jelly;  they  are 
flexible,  so  that  a  long  bone  can  be  bent  into  a  complete 
ring,  and  no  opacity  or  spot  of  ossification  is  seen." 

The  development  of  bone  consists  of  three  stages — 

1.  The  Mucous.     2.  The  Cartilaginous.     3.  The  Osseous. 

The  mucous  stage  presents  bone,  like  all  the  other  tis- 
sues, in  the  earliest  period  of  the  embyro,  as  one  homoge- 


DEVELOPMENT  OF  BONE. 

neous  fluid  mass,  not  having  any  characters  hy  which  the 
one  can  he  distinguished  from  the  other. 

Ahout  the  expiration,  however,  of  the  first  month  after 
conception  the  mucous  stage  "becomes  converted  into  the 
cartilaginous,  which  greatly  increases  the  consistence  of 
hone,  and  is  the  commencement  of  form  in  the  foetus. 
Agreahly  to  the  observations  of  Bichat  and  Scarpa,  the 
cartilaginous  condition  presents  two  peculiarities.  The 
first  is_,  that  during  the  formation  of  cartilage  we  do  not 
see  the  longitudinal  strige  of  the  long  hones,  the  radiated  of 
the  flat,  nor  the  mixed  of  the  thick,  which  distinguish  the 
osseous  or  third  stage.  The  second  peculiarity  is,  that  all 
those  hones  which  are  to  he  united  hy  cartilage  in  the  adult 
skeleton,  are  in  one  piece,  as  those  of  the  vertebrae  and  pel- 
vis, while  those  which  are  to  he  united  hy  ligament,  and, 
consequently  movahle,  are  isolated,  as  the  femur,  tibia,  &e. 

The  cartilaginous  condition  is  complete  at  the  end  of  the 
first  or  beginning  of  the  second  month,  when  the  third  or 
osseous  stage  commences.  This  event  is  announced  by  the 
arrival  of  red  blood,  which  first  shows  itself  in  the  centre 
of  the  cartilage,  and  the  spot  receives  the  name  of  the 
"punctum  ossificationis"  or  point  where  ossification  first 
commences.  It  appears  that  until  this  period  it  is  not  in 
direct  relation  with  the  blood,  but,  according  to  Carpenter, 
is  surrounded  by  blood  vessels  which  have  "large  ampullae 
or  varicose  dilatations,"  from  whence,  and  by  imbibition,  it 
is  nourished. 

The  manner  of  ossification  is  somewhat  modified  in  the 
three  classes  of  bones.  In  the  long  bones  there  is  first  seen 
a  central  ring,  whose  cavity  is  the  commencement  of  the 
medullary  canal.  This  ring,  forming  the  bony  nucleus, 
gradually  grows  in  length  and  thickness  till  the  period  of 
birth  arrives,  when  we  have  the  body  or  diaphysis  gene- 
rally finished.  The  epiphysis,  or  extremities  of  the  long 
bones,  do  not  commence  ossifying  till  after  birth,  when  we 
observe  the  point  of  ossification,  as  in  the  body,  occupying 
the  centre  and  extending  towards  the  shaft.  This  process 
is  not  entirely  complete,  so  that  the  different  parts  become 


1*72  DEVELOPMENT  OP  BONK 

fused  into  one  solid  bone,  till,  according  to  the  observa- 
tions made,  the  individual  has  advanced  to  the  sixteenth 
or  eighteenth  year  of  age,  or  even  till  later  in  life. 

Ossification  of  the  flat  bones  takes  place  between  mem- 
branes, but,  nevertheless,  in  cartilage  also,  which,  however, 
is  so  small  in  quantity  as  to  lead  some  to  deny  its  existence. 
The  point  where  the  bony  matter  is  first  deposited  depends 
on  the  bone  being  either  single  or  compound  in  its  nature. 
The  parietal  has  one  point  of  ossification,  the  frontal  two, 
and  the  occipital  several,  from  which  points  the  osseous 
fibres  radiate  in  every  direction,  till,  at  the  period  of  birth, 
we  have  the  whole  bony  casement  for  the  head  complete, 
excepting  the  fontanelles,  which  are  not  closed  till  the  third 
year  after  birth. 

The  thick  bones  have  one  or  more  points  of  ossifica- 
tion, according  as  they  are  either  single  or  double.  The 
carpus  and  tarsus  present  specimens  of  the  former  variety, 
while  the  bones  of  the  vertebra?  furnish  examples  of  the 
latter. 

There  yet  remains  great  obscurity  in  regard  to  the  pre- 
cise manner  in  which  cartilage  is  changed  or  becomes  bone. 
The  microscope  shows  cartilage  to  contain,  or,  as  Von  Behr 
expresses  it,  consist  of  a  mass  of  homogeneous  cells,  carti- 
lage cells,  in  the  centre  of  which  the  medullary  canaliculi 
or  Haversian  canals  are  formed,  surrounded  by  capillary 
vessels.  In  the  parietes  of  these  canals  and  in  the  lamellae, 
the  lacunas  or  corpuscles  and  the  calcigerous  tubes  appear, 
after  which  the  deposit  of  osseous  matter  seems  to  take  place. 
The  cartilage  cells  are  regarded  as  the  basis  of  this  change. 
Ossification  does  not  commence  at  the  same  time  in  all  the 
bones.  At  the  end  of  the  first  month  the  clavicle  and  lower 
jaw  are  found  to  be  partly  ossified;  at  the  end  of  the  second, 
the  bodies  of  the  long  bones,  the  ribs,  vertebras,  base  of  the 
skull,  and  pelvis  have  commenced  ossifying;  and  from  this 
time  to  that  of  birth,  there  are  only  a  few  in  which  ossifica- 
tion has  not  begun,  such  as  the  patella?  and  a  few  bones  of 
the  tarsus  and  carpus.  The  ossific  process  is  much  more 
rapid  in  some  bones  than  others,  and  in  some  parts  of  the 


DEVELOPMENT  OF  BONE.  1*73 

same  bone;  thus,  the  body  of  a  long  bone  is  completed  a 
very  considerable  period  before  its  extremity. 

The  growth  of  bones  occurs  and  steadily  progresses,  as 
that  of  every  other  tissue,  till  the  individual  reaches  the 
full  stature;  and  this  is  accomplished  by  successively  add- 
ing new  matter  to  the  old. 

Mr.  Jno.  Hunter  showed  that  the  long  bones  grew  by  the 
addition  of  osseous  matter  at  their  extremities.  This  he 
proved  by  boring  a  hole  at  each  extremity  in  the  tibia  of  a 
pig,  and  inserting  a  shot  in  each,  The  distance  between 
the  two  holes  was  accurately  measured.  After  some  months 
the  same  bone  was  again  examined,  and  it  was  found  that 
the  distance  between  the  shots  was  precisely  the  same,  but 
that  the  extremities  had  extended  very  considerably. 

The  flat  bones  grow  in  breadth  by  a  deposition  at  their 
margins,  while  the  thickness  of  bone  is  believed  to  depend 
upon  a  secretion  from  the  internal  surface  of  the  perios- 
teum. 

When  the  full  size  of  the  bones  has  been  attained,  the 
subsequent  changes  which  occur  are  those  of  interstitial 
deposit  and  absorption. 

Formation  of  Callus. — Callus  is  the  mode  of  union  between 
fractured  bones,  and  resembles  very  much  the  original  pro- 
cess in  the  formation  of  bone. 

When  the  swelling  subsides  and  the  effusion  of  blood  is 
absorbed,  coagulable  lymph  is  poured  out  in  the  cavity  of 
the  fracture.  This  corresponds  to  the  first  or  mucous  stage 
in  the  foetal  bone.  An  osseous  ring  is  seen  to  encircle  the 
place  of  fracture,  while  in  the  interior  there  is  found  an 
osseous  pin.  These  are  simply  temporary  arrangements, 
which  are  removed  by  absorption,  when  the  bones  begin  to 
coalesce  and  become  fused  the  one  into  another.* 

*  The  recent  observations  of  Messrs.  Paget,  Stanly  and  Dr.  Hamilton  throw 
great  doubt  on  this  statement  of  Dupuytren,  in  regard  to  provisional  calliis.  In 
the  lower  animals,  whose  fractured  limbs  are  subjected  to  so  much  greater 
motion  than  ours,  and  which,  under  such  circumstances,  secrete  so  much  more 
bony  matter,  this  account  of  the  process  of  repair  is  undoubtedly  correct ;  but 
in  man,  according  to  these  more  recent  observers,  no  provisional  callus  has 
been  formed,  unless  undue  motion  and  excitement  has  induced  irritation.  The 


1T4  DEVELOPMENT  OF  BONK 

The  periosteum,  with  some,  has  the  sole  credit  of  form- 
ing callus;  hut  this  cannot  he  entirely  true,  as  instances 
have  occurred  where  the  periosteum  has  heen  stripped  off, 
and  yet  the  fractured  hones  have  united,  callus  has  heen 
formed,  and  the  periosteum  itself  again  restored.  Bichat 
supposes  that  where  the  hones  are  not  kept  in  contact, 
granulations  spring  up,  and  form  first  a  gelatinous  deposit, 
then  cartilage,  and,  finally,  hone,  when  the  fractured  ends 
are  perfectly  restored. 

The  tissues  composing  the  letters  of  the  alphahet,  and 
which  have  just  heen  examined,  are  variously  comhined  to 
form  the  different  organs  of  the  hody,  constituting  the 
language  of  anatomy,  which  introduces  us  to  the  Second 
Part,  "beginning  with  the  head. 

coagulable  lymph  is  effused  between  the  broken  ends  of  the  bone,  and  the  pro- 
cess goes  on  like  adhesion  any  where  else,  with  this  difference,  that  phosphate 
of  lime  is  afterwards  deposited  in  the  new  tissne.  See  Ranking^  Abstract, 
1850,  and  Buffalo  Medical  Journal  for  February,  1853. 


PART  SECOND. 


THE  LANGUAGE  OF  AMTOMY. 

I.  THE  HEAD. 


PART  SECOND. 


CHAPTEK  I. 

PASSIVE   ORGANS    OF    THE   HEAD. 
THE  BONES. 

THE  head  is  divided  into  cranium  and  face.  The  former 
consists  of  eight  distinct  bones:  one  frontal,  two  parie- 
tal;  one  occipital,  two  temporal,  one  ethmoid,  and  one 
sphenoid.  These,  when  united,  in  consequence  of  their 
peculiar  form,  strength,  and  structure,  are  well  adapted  to 
receive  the  brain,  and  guard  it  from  injury. 

The  face  has  fourteen  bones:  two  superior  maxillary,  two 
malar,  two  palatal,  two  lachrymal,  two  nasal,  two  inferior 
turbinated,  one  vomer,  and  one  inferior  maxillary  bone. 
These  contain  most  of  the  organs  of  sense. 

SECTION  I.' 
BONES  OF  THE  CRANIUM. 

Frontal  Bone—(os  frontis.)  The  frontal  bone  (Fig.  33) 
is  situated  at  the  anterior  and  upper  part  of  the  cra- 
nium. Its  form  is  semi-circular.  Its  division  is  into  two 
parts,  the  superior  or  frontal,  and  the  inferior  or  orbital. 
The  frontal  portion  has  two  surfaces,  an  external  and  in- 
ternal. The  external  surface  is  anterior,  smooth  and  convex. 
Along  the  median  line  there  is  an  elevation,  not  always  dis- 
tinct, corresponding  to  the  original  separation  of  the  foetal 
bone,  into  two  equal  parts,  by  the  frontal  suture,  which 
sometimes  continues  in  the  adult  bone.  At  the  lower  part  of 
this  line  of  division,  is  the  nasal  prominence,  which  termin- 
ates in  a  rough  edge,  for  articulating  with  the  nasal  process 
of  the  superior  maxillary  and  nasal  bones.  The  nasal  spine 
12 


m 


BONES  OF   THE   CRANIUM. 


FIG.  34. 


or  process  arises  from  the  FlG- 

centre  of  this  rough  edge, 
and  supports  the  eth- 
moid hone  "behind  and 
the  nasal  hones  in  front. 

On  either  side  of  the 
median  line  and  ahout 
the  centre  of  each  lateral 
half,  is  the  frontal  emin- 
ence. Ahove  this  the  sur- 
face is  smooth,  helow  it 
is  the  superciliary  arch, 
which  supports  the  eye-hrow  ;  and  helow  this  again  is  the 
upper  margin  of  the  orhit,  the  supra-orbital  ridge.  This 
ridge  terminates  at  its  out- 
er  end  in  the  external  an- 
gular process,  and  at  its 
inner,  in  the  internal  an- 
gular process.  At  the  in- 
ner third  of  this  ridge  is  a 
notch,  converted  into  a  fora- 
men hy  a  ligament,  for 
transmitting  the  supra-or- 
bital vessels  and  nerve,  and 
just  ahove  its  inner  third 
is  the  prominence  of  the 
frontal  sinus. 

On  the  internal  surface,   the  median   line   marks  the 

FIG.  33  presents  a  front  view  of  the  Frontal  Bone,  a  Frontal  protuberance 
of  right  side.  6  Superciliary  ridge,  c  Supra  orbital  ridge,  d  External  an- 
gular process,  e  Internal  angular  process.  /  Supra  orbitar  notch  or  foramen. 
g  Nasal  protuberance,  h  Semi-circular  ridge  for  temporal  muscle,  i  Nasal 
spine. 

FIG.  34  presents  a  view  of  inner  surface  of  Frontal  Bone,  a  Coronal  suture 
for  joining  frontal  and  parietal  bones,  b  Ridge  for  attachment  of  falx-major. 
c  Foramen  coecum.  d  Nasal  spine,  e  Openings  of  the  frontal  sinuses. 
/  Orbitar  plates,  g-  External  angular  process,  h  Serrated  surface  of  sphe- 
noid bone.  i  Line  of  junction  of  parietal  bones,  j  Depression  for  glands  of 
Pacchioni.  fc  Squamous  portion  of  temporal  bone. 


BONES  OP  THE    CRANIUM.  179 

course  of  the  superior  longitudinal  sinus  by  a  groove.  The 
inferior  portion  of  this  groove  presents  a  ridge  to  which 
ihefalx  major  is  attached.  And  at  this  point  where  it  joins 
the  ethmoid  is  seen  a  small  hole,  the  foramen  ccecum,  for 
transmitting  a  vein  which  communicates  with  the  nasal 
veins,  and  for  lodging  a  process  of  the  dura-mater.  On 
either  side  of  the  median  line,  many  eminences  and  de- 
pressions are  observed,  which  correspond  to  the  convolu- 
tions of  the  brain,  called  mammillary  eminences,  and  digital 


The  circumference  is  rough  and  serrated  to  unite  with 
the  parietal  bones.  At  its  superior  border  the  internal 
table  is  deficient,  and  rests  upon  the  junction  of  the  two 
parietal  bones  above;  while,  at  the  sides  and  below,  the 
external  is  wanting  and  is  overlapped  by  the  parietal. 

The  inferior  or  orbi-  FIG.  35. 

tal  division  of  the  fron- 
tal bone  presents  in  its 
centre  the  azthmoidal 
notch,  in  front  of  which 
is  the  nasal  spine;  and 
on  either  side,  the  ori- 
fices of  the  frontal  sin- 
uses. It  communicates 
with  the  cells  of  the  ethmoid  by  means  of  its  edges,  whi  ch 
are  cellular.  Along  the  margins  of  this  notch,  where  it 
unites  with  the  ethmoid,  are  two  foramina,  the  anterior  and 
posterior  orbital,  the  first  transmitting  the  nasal  twig  of 
the  ophthalmic  nerve  and  anterior  ethmoidal  artery  —  the 
second  the  posterior  ethmoidal  artery. 

The  orbital  processes,  on  either  side  of  this  notch,  are 
triangular,  having  the  apex  behind,  smooth  and  concave 
below,  rough  and  convex  above.  Near  the  external  angu- 
lar process,  each  of  them  has  a  depression  for  the  lachrymal 

FIG.  35  presents  a  view  of  the  lower  part  of  Frontal  Bone,  a  Line  where 
the  two  halves  of  the  bone  join.  6  Frontal  protuberances,  c  Supra  orbitar 
notch,  d  Nasal  spine  and  space  occupied  by  the  sethmoid  bone,  e  Frontal 
sinuses.  /  Orbitar  plates,  g  External  angular  process,  h  Surface  for  tem- 
poral muscle.  • 


180  BONES  OF  THE    CRANIUM. 

gland,  and  near  the  internal,  one  for  the  pulley  of  the 
superior  oblique  muscle  of  the  eye.  Instead  of  a  depres- 
sion, there  is  sometimes  a  small  eminence  here. ' 

The  frontal  bone  has  seven  foramina:  2  supra  orbital, 
which  are  special ;  2  anterior  and  2  posterior  orbital,  with 

1  foramen  ccecum,  which  are  common  to  both  the  ethmoid 
and  frontal  bones. 

The  processes  are  nine :  1  nasal,  2  orbital,  4  angular,  and 

2  superciliary. 

The  structure  consists  of  two  compact  laminae  of  bone, 
called  the  external  and  internal  tables,  with  an  intervening 
cellular  substance,  the  diploe. 

The  development  of  the  frontal  bone  takes  place  by  two 
points  of  ossification,  one  for  each  frontal  eminence,  or 
rather  in  the  orbital  arches,  a  little  before  that  of  the  ver- 
tebrae, whence  the  rays  radiate  to  the  circumference.  At 
birth  the  frontal  bone  still  consists  of  two  pieces,  which 
during  the  first  year  unite  along  the  median  line  by  the 
frontal  suture,  which  suture  however  sometimes  remains 
permanent  through  life. 

FIG  36  The  articulations  of  this 

bone,  are  with  four  of  the 
cranium,  viz :  the  2  pari- 
etal, the  sphenoid  and  eth- 
moid; and  eight  of  the 
face,  viz:  2  nasal,  2  supe- 
rior maxillary,  2  malar 
and  2  lachrymal. 

Parietal  Bones — (oss-a 
parietalia.)  The  parietal 
bones  are  situated  upon 
the  lateral  and  superior  parts  of  the  cranium.  They  are 
symmetrical.  Their  form  is  quadrilateral ;  their  external 

FIG.  36  represents  external  surface  of  left  Parietal  Bone,  a  Superior  or 
sagittal  surface.  6  Squamous  or  inferior  surface,  c  Coronal  or  anterior  sur- 
face, d  Lambdoidal  or  posterior  surface,  e  Ridge  where  temporal  muscle 
is  attached.  /  Parietal  foramen,  g  Inferior  anterior  angle,  h  Inferior  pos- 
terior angle. 


BONES  OP  THE  CRANIUM.  181 

surface  is  smooth  and  convex,  in  the  centre  of  which  is  the 
parietal  protuberance.  On  either  side  of  this  protuberance, 
and  extending  in  an  arched  direction  transversely  across 
the  hone  is  the  temporal  FlG- 37- 

ridge;  helow  this  ridge  the 
temporal  muscle  is  attach- 
ed, above  the  aponeurosis 
of  the  occipito-frontalis. — 
The  inner  or  cerebral  sur- 
face is  marked  by  the  mid- 
dle artery  of  the  dura  ma- 
ter, and  the  convolutions  of 
the  brain.  The  trunk  of 
this  artery  is  seen  in  the 
anterior  inferior  angle  of 
the  bone,  lodged  in  a  groove,  and  branching  upwards  and 
backwards. 

The  circumference  presents  four  edges  and.  four  angles,  the 
anterior  edge  is  serrated  and  unites  with  the  frontal  bone  in 
the  coronal  suture.  The  posterior  is  very  irregular  and 
joins  the  occipital  in  the  lambdoid  suture.  The  superior  is 
the  longest  and  meets  its  fellow  on  the  middle  line  in  the 
sagittal  suture.  The  inferior  is  the  shortest,  is  thin,  and 
unites  with  the  temporal  by  the  squamous  suture. 

Of  the  angles,  the  anterior  superior  is  nearly  straight ; 
this,  in  the  infant  is  wanting,  the  anterior  fontanelle  or  open- 
ing taking  its  place.  This  opening  is  four-cornered,  and 
is  made  so  by  a  similar  deficiency  in  the  superior  project- 
ing points  of  the  frontal  bone.  The  anterior  inferior  angle 
is  long  and  curved,  and  unites  with  the  sphenoid  bone. 
The  posterior  superior  is  rounded,  and  by  its  deficiency 
forms  the  posterior  fontanelle.  The  posterior  inferior  is 
very  irregular  and  unites  with  the  mastoid  portion  of  the 
temporal. 

FIG.  37  represents  internal  surface  of  left  Parietal  Bone,  a  Sagittal  suture, 
6  Line  for  squamous  suture,  c  Coronal  suture,  d  Lambdoidal  suture. 
«  Groove  for  superior  longitudinal  sinus.  /  Parietal  foramen,  g  Inferior  ante- 
rior angle  and  groove  for  middle  artery  of  dura  mater,  h  Inferior  poste- 
rior angle.  ^ 


182 


BONES  OP  THE  CRANIUM. 


FIG.  38. 


Along  the  sagittal  suture,  on  the  interior,  is  a  groove  for 
lodging  the  superior  longitudinal  sinus. 

The  structure  is  thin  and  consists  of  two  compact  tables 
and  an  intervening  diploe.  The  development  takes  place  by 
one  point  of  ossification  "in  each  parietal  protuberance,  com- 
mencing about  the  seventh  or  eighth  week. 

The  parietal  articulates  with  five  bones,  the  frontal, 
occipital,  temporal,  sphenoid,  and  its  fellow. 

Occipital  Bone — (os  occipitis.)  The  occipital  bone  is  sit- 
uated at  the  posterior  in- 
ferior part  of  the  cranium 
Its  form  is  rhomboidal.  It 
has  two  surfaces,  an  ex- 
ternal and  internal.  The 
external  is  irregularly  con- 
vex, and  has  near  its  cen- 
tre the  external  occipital 
protuberance,  to  which  the 
cervical  ligament  is  at- 
tached. On  either  side 
extends,  transversely,  the 
superior  transverse  ridge, 
to  which  the  trapezii  and  posterior  bellies  of  the  occipito- 
frontales  muscles  are  connected.  A  short  distance  below  is 
the  inferior  transverse  ridge,  and  below  this  again,  on  the 
inferior  surface  is  the  foramen^nagnum.  The  space  between 
the  two  ridges  is  occupied  by  the  complexi  and  splenii 
muscles.  The  inferior  ridge  and  the  space  between  it  and 
the  foramen  magnum,  gives  attachment  to  the  posterior  recti 
and  superior  oblique  muscles. 

The  foramen  magnum  has  leading  to  it  from  the  occipital 
protuberance,  a  vertical  ridge.  Its  shape  is  oval,  and  it 

FIG.  38  represents  the  external  surface  of  the  Occipital  Bone,  a  Superior 
•semi-circular  ridge.  6  External  occipital  protuberance,  c  Point  where  the 
ligamentum  nuchae  is  attached,  d  Inferior  semi-circular  ridge,  e  Foramen 
magnum.  /  Condyle  of  the  right  side,  g  Posterior  condyloid  foramen,  h  An- 
terior condyloid  foramen,  i  Jugular  eminence,  j  Part  of  jugular  foramen. 
&  Basilar  process.  I  Where  odontoid  ligaments  are  attached,  m  Surface  for 
parietal  bones,  n  Surface  for  mastoid  portion  of  temporal  bone. 


BONES  OF  THE  CRANIUM.  183 

transmits  the  spinal  marrow  and  its  membranes,  the  ver- 
tebral arteries  and  the  spinal-accessory  and  sub-occipital 
nerves.  In  front  of  it  is  the  cuneiform  or  basilar  process, 
which  extends  forward  upon  the  base  of  the  cranium  to 
unite  with  the  sphenoid  bone.  The  inferior  surface  of  this 
process  is  rough  and  gives  attachment  to  the  pharynx,  and 
superior  and  middle  constrictor  muscles. 

On  each  side  of  the  foramen  magnum  and  near  its  fore- 
part, are  the  two  oondyles  for  articulating  with  the  atlas. 
They  are  smooth  oblong  processes  which  converge  ante- 
riorly, and  look  downwards  and  outwards,  posteriorly.  In 
front  and  at  their  base,  is  the  anterior  oondyloid for  amen,  for 
transmitting  the  ninth  or  lingual  nerves,  and  behind  is  a 
small  foramen,  the  posterior  condyloid,  for  the  passage 
of  a  vein  to  the  lateral 
sinus.  Each  condyle  has 
on  its  outside  the  jugular 
eminence  or  transverse 
process,  which  forms  the 
posterior  boundary  of  the 
foramen  lacerum  basis 
cranii  posterius,  and  to 
which  is  attached  the  rec- 
tus  lateralis  muscle. 

The  internal  or  cerebral 
surface  is  concave,  and  in-  v  / 

tersected  by  the  crucial  * '  j 

ridge,  which  divides  it  into  four  occipital  fosses,  two  superior 
for  lodging  the  posterior  lobes  of  the  cerebrum,  and  two 
inferior  for  the  cerebellum.  In  the  centre  where  these 
ridges  cross  each  other,  is  the  internal-occipital  protuberance, 

FIG.  39  represents  the  internal  surface  of  the  Occipital  Bone,  a  Foramen 
magnum.  6  Ridge  for  falx-minor.  c  Internal  occipital  protuberance,  d  d 
Lateral  branches  of  the  occipital  cross,  and  depression  for  lateral  sinus,  e  Sur- 
face for  parietal  bones.  /  Jugular  eminence,  g  Jugular  fossa,  'h  Internal 
opening  of  condyloid  foramen,  i  Surface  for  petrous  portion  of  temporal  bone, 
j  j  Condyles.  k  Anterior  extremity  of  cuneiform  process.  I  I  Exterior  edge 
of  basilar  gutter,  m  m  Surface  for  mastoid  portion  of  temporal,  n  n  Cavity 
for  Cerebellum,  o  o  Cavity  for  posterior  lobes  of  cerebrum. 


184  BONES  OF  THE  CRANIUM. 

which  corresponds  to  the  torcular  Heropliili.  The  transverse 
ridge  has  attached  to  it  the  tentorium,  and  is  grooved  for  the 
lateral  sinuses.  The  vertical  ridge  has  attached  to  its  su- 
perior part  the  falx  cerebri,  and  to  its  inferior  portion  the 
falx  cerebelli.  The  cerebral  surface  of  the  basilar  process,  is 
concave  and  supports  the  pons  varolii  and  basilar  artery. 

The  foramina  are  seven :  5  proper  and  2  common.  The 
proper  are  the  4  condyloid,  2  anterior  and  2  posterior,  and 
the  foramen  magnum.  The  common  are  the  2  foramina 
lacera  posteriora.  The  processes  are  seven :  1  cuneiform,  2 
eondyles,  2  jugular,  and  2  occipital  protuberances. 

This  bone  has  four  angles :  a  superior,  which  unites  with 
the  parietal  bones,  an  inferior,  which  is  attached  to  the 
sphenoid;  and  two  lateral,  which  are  blunt,  and  occupy  the 
spaces  between  the  mastoid  portion  of  the  temporal  and 
posterior  inferior  angle  of  the  parietal  bones. 

The  structure  consists  of  two  compact  tables  and  an  in- 
termediate diploe.  The  tables  are  so  compact  and  thin  in 
the  fossae,  as  to  be  diaphanous.  The  spongy  tissue  prevails 
in  the  processes.  This  bone  is  firm  and  hard,  and  in  many 
places  thick. 

Its  development  is  from  seven  points :  one  for  the  basilar 
process,  one  for  each  condyle,  and  four  for  the  superior  part. 
Ossification  begins  in  the  superior  portion  before  it  does 
in  the  vertebrae,  by  four  osseous  points,  two  above  and 
two  below  the  occipital  protuberance,  which  scon  unite  to 
form  a  single  piece.  At  birth  the  occipital  bone  is  seen  in 
four  pieces,  which  become  united  to  each  other  from  the 
fourth  to  the  sixth  year,  and  with  the  sphenoid  by  the 
basilar  process,  about  the  twentieth  year. 

The  occipital  bone  is  articulated  with  six  bones:  the 
sphenoid,  2  temporal,  2  parietal  and  the  atlas. 

Temporal  Bones — (Ossa  Temporum,  Bones  of  Time) 
The  situation  of  the  temporal  bones  is  at  the  side,  middle 
and  inferior  parts  of  the  cranium.  The  form  is  very  irreg- 
ular, and  each  is  divided  into  the  squamous,  mastoid  and 
petrous  portions. 

The  squamous,  or  scaly  part,  forms  the  superior  divis- 


BONES  OF  THE   CRANIUM.  185 

ion.  Its  external  surface  is 
flat;  forms  a  portion  of  the 
temporal  fossa,  and  gives  at- 
tachment to  the  temporal 
muscle.  Its  internal  sur- 
face has  depressions  for  the 
convolutions  of  the  brain, 
and  a  groove  for  the  poste- 
rior branch  of  the  middle 
meningeal  artery. 

It  is  bounded  above  by  a 
somewhat  semicircular  edge, 
which  overlaps  the  parietal  bone — and  below  by  a  long  and 
curved  process,  with  its  convexity  outwards,  called  the  zygo- 
ma, or  zygomatic  process.  This  process  is  horizontal,  and 
arises  by  two  roots — the  one  runs  transversely,  is  covered  by 
cartilage,  and  forms  the  anterior  boundary  of  the  glenoid 
cavity — the  other  passes  horizontally  backwards,  forming 
the  outer  boundary  of  the  glenoid  cavity,  and  is  contin- 
ued on  and  lost  in  the  upper  part  of  the  mastoid  process. 
This  posterior  root  gives  off  a  middle  branch,  which  passes 
into  the  glenoid  fissure,  and  partially  forms  the  posterior 
wall  of  the  glenoid  cavity.  At  the  junction  of  the  hori- 
zontal and  transverse  roots  there  is  seen  a  small  tubercle, 
giving  attachment  to  the  external  lateral  ligament  of  the 
lower  jaw — the  anterior  extremity  of  the  zygoma  is  serra- 
ted and  rests  on  the  malar  bone.  Behind  the  transverse 
root  is  the  glenoid  cavity,  which  is  divided  by  a  fissure 
called  the  Glasserian — that  portion  of  the  glenoid  cavity 
in  front  of  this  fissure  is  the  proper  articulating  surface  of 
the  lower  jaw,  while  that  behind  the  fissure  is  occupied  by 
a  portion  of  the  parotid  gland — the  fissure  has  attached  to 

FIG.  40  represents  external  surface  of  left  Temporal  Bone,  a  Squamous 
portion.  &  Mastoid  portion,  c  Extremity  of  petrous  portion,  d  Zygomatic 
process,  e  Tubercle  in  front  of  articular  surface  for  condyle  of  lower  jaw. 
/  Temporal  ridge,  posterior  portion,  g  Glenoid  fissure,  h  Mastoid  foramen. 
i  Meatus  auditorius  externus.  j  Digastric  fossa,  k  Styloid  process.  I  Va- 
ginal process,  m  Glenoid  foramen,  n  Groove  for  the  Eustachian  tube. 


186  BONES  OF  THE   CRANIUM. 

it  the  capsular  ligament  of  the  lower  jaw,  and  gives 
passage  to  the  corda  tympani  nerve,  the  laxator  tympani 
muscle,  and  the  processus  gracilis  of  the  malleus. 

The  mastoid,  so  called  from  its  resemblance  to  a  nipple, 
is  situated  at  the  posterior  and  inferior  part  of  the  bone. 
It  is  a  rough  and  depending  process,  having  on  its  internal 
aspect  two  grooves— the  one  for  giving  origin  to  the  digas- 
tric muscle— the  other,  a  little  posterior,  transmits  the  oc- 
cipital artery.  The  outer  surface  of  this  process  gives  at- 
tachment to  the  sterno-cleido-mastoideus  muscle;  on  the 
posterior  part  of  this  process  is  generally  seen  the  mastoid 
foramen,  for  transmitting  the  mastoid  artery  and  vein. 

FlG>  4L     .  The  cerebral  surface  of  this 

process  is  concave,  and  deeply 
grooved  for  lodging  the  lateral 
sinus.  The  third  or  petrous 
portion,  named  from  its  stony 
hardness,  is  situated  between 
the  squamous  and  mastoid, 
and  proceeds  forwards  and 
inwards  into  the  base  of  the 
cranium.  Its/orm  is  triangu- 
lar, with  the  base  posterior, 

and  presents  three  surfaces,  one  external  or  inferior,  and 
two  internal  or  cerebral. 

On  the  inferior  surface  are  noticed  the  following  points : 
first  and  most  prominent,  the  styloid  process,  a  long,  slen- 
der projection,  sometimes  two  inches  in  length,  giving  at- 
tachment to  the  three  styloid  muscles  and  two  ligaments. 
Behind  and  at  the  root  of  this  process,  between  it  and 

FIG.  41  represents  the  cerebral  surface  of  the  Temporal  Bone.  1  Squamous 
portion.  2  Mastoid.  3  Petrous  portion.  4  Groove  for  the  middle  meningeal 
artery.  5  Edge  of  squamous  suture.  6  Zygomatic  process.  7  Digastric 
fossa.  8  Occipital  groove.  9  Groove  for  lateral  sinus.  10  Superior  petrous 
sinus.  11  Opening  of  the  carotid  canal.  12  Internal  auditory  foramen.  13 
Aqueduct  of  the  vestibule.  14  Styloid  process.  15  Stylo  mastoid  foramen. 
16  Foramen  caroticum.  17  Spine  dividing  the  jugular  vein  from  the  eighth 
pair  of  nerves.  18  Vidian  foramen.  19  Where  the  levator  palati  and  ten- 
sor tympani  muscles  arise. 


BONES  OF  THE  CRANIUM.  1ST 

the  mastoid  is  the  stylo-mastoid  foramen,  for  transmitting 
the  facial  nerve,  or  portio  dura  of  the  seventh  pair.  This 
foramen  is  the  lower  aperture  of  the  aqueduct  of  Fallopius. 
The  styloid  process  is  surrounded  by  a  process  at  its 
root,  very  prominent  anteriorly,  called  the  vaginal,  which 
separates  the  glenoid  cavity  from  the  carotid  foramen,  and 
foramen  lacerum  posterius. 

In  front  and  obliquely  to  the  inside  of  the  styloid  process 
is  the  foramen  caroticum  leading  into  a  canal,  the  carotid 
canal,  which  is  first  vertical,  and  then  proceeds  forwards, 
inwards  and  upwards,  and  opens  within  the  cranium,  by 
the  side  of  the  body  of  the  sphenoid  bone.  It  gives  passage 
to  the  carotid  artery  and  branches  of  the  sympathetic  nerve. 
In  front  of  the  carotid  foramen  is  a  rough  surface  for  the 
origin  of  the  levator  palati  muscle.  By  the  side  of  the  styloid 
process  is  a  vertical  ridge,  within  and  posterior  to  which  is 
a  deep  cavity  called  the  jugular  fossa.  This,  with  a  corre- 
sponding one  in  the  occipital  bone,  constitutes  the  foramen 
lacerum  posterius,  through  which  passes  the  eighth  pair  of 
nerves  and  the  lateral  sinus,  the  nerves  being  anterior  and 
separated  from  the  sinus,  which  is  posterior,  by  the  vertical 
or  jugular  spine.  Upon  this  ridge  is  described  the  opening 
of  the  aqueduct  of  the  cochlea.  The  angle  between  the 
squamous  and  petrous  portions  is  occupied  by  the  spinous 
process  of  the  sphenoid  bone.  At  this  point  there  are  two 
canals,  the  one  above,  the  other  below,  separated  by  a  thin 
plate  of  bone;  the  upper  gives  origin  to  the  tensor  tympani 
muscle,  the  lower  is  the  bony  part  of  the  Eustachian  tube, 
and  both  go  to  the  tympanum.  The  cerebral  surface  of  the 
petrous  portion  is  divided  by  a  sharp  ridge,  to  which  is  at- 
tached the  tentoriunr,  into  an  anterior  and  posterior  surface. 
On  the  anterior  or  superior  surface  is  seen  a  depression  for 
receiving  the  Gasserian  ganglion  of  the  fifth  pair  of  nerves. 
Near  this  is  a  groove  leading  to  an  opening  about  the  mid- 
dle of  this  surface,  called  the  hiatus  Fallopii,  which  leads  to 
the  aqueduct  of  Fallopius,  and  transmits  the  superior  branch 
of  the  Vidian  nerve.  This  surface  is  marked  by  an  emi- 
nence for  the  superior  semi-circular  canal,  and  by  depressions 


188  BONES  OP  THE  CKANIUM. 

for  the  convolutions  of  the  brain.    Its  superior  ridge  con- 
tains a  groove  for  lodging  the  superior  petrosal  sinus. 

The  posterior  surface  has  about  its  centre  a  large  open- 
ing, the  meatus  auditorius  internus,  which  gives  passage  to 
the  seventh  pair  of  nerves.  It  is  directed  outwards  and 
somewhat  forwards  into  a  short  canal,  at  whose  termina- 
tion there  is  a  transverse  ridge  dividing  it  into  two  parts. 
The  inferior  is  cribriform  and  transmits  the  portio  mollis 
or  auditory  nerve,  while  the  superior  is  a  single  foramen, 
which  leads  to  the  aqueduct  ofFallopius,  and  gives  passage 
to  the  portio  dura  or  the  facial  nerve.  This  aqueduct  of 
Fallopius  is  a  long  canal  passing  outwards  and  downwards 
behind  the  tympanum  and  terminating  in  the  stylo-mastoid 
foramen.  Behind  the  meatus  internus  is  a  small  orifice, 
the  aqueduct  of  the  vestibule.  The  base  or  exterior  mar- 
gin of  the  petrous  portion  is  rough,  for  the  attachment  of 
the  cartilage  of  the  ear,  and  at  this  point  is  seen  the  fora- 
men auditorium  externum  which  leads  into  the  auditory  ca- 
nal, a  tube  about  a  half  an  inch  long  that  takes  a  curved 
direction  downwards,,  inwards,  and  forwards,  to  the  mem- 
bran  a-tympani.  This  canal  is  composed  chiefly  of  what  is 
called  the  auditory  process.  The  petrous  bone  also  contains 
the  organs  of  hearing,  which  will  be  examined  in  another 
place. 

The  foramina  are  twelve  in  number,  10  special  and  2  com- 
mon. The  special  are  the  external  and  internal  auditory, 
the  stylo-mastoid,  the  mastoid,  the  carotid,  glenoidal,  Eusta- 
chian,  Vidian,  aqueductus  cochleae,  and  vestibuli.  The  com- 
mon are  the  anterior  and  posterior  foramina  lacera. 
The  processes  enumerated  are  six — the  styloid,  the  mastoid, 
the  auditory,  the  vaginal,  the  zygomatic,  and  the  jugular. 
The  structure  of  the  temporal  bone,  in  its  squamous  por- 
tion, is  thin  and  mostly  compact;  the  mastoid  contains 
large  cells,  and  the  petrous  is  considered  next  in  density 
to  the  teeth.  Its  development  takes  place  by  six  points,  viz  : 
the  squamous,  mastoid,  petrous,  zygomatic,  styloid,  and 
auditory. 

The  first  osseous  point  is  seen  in  the  squamous  about  the 


BONES  OF  THE  CKANIUM.  189 

end  of  the  second  month;  very  soon  afterward  the  petrous 
portion  begins  to  ossify;  in  the  fifth  month  the  mastoid, 
and  the  last  of  all  the  styloid. 

The  squamous,  mastoid,  and  petrous  portions  become  uni- 
ted during  the  first  year.  The  styloid  process  is  not  con- 
nected with  the  petrous  portion  for  several  years  after  birth, 
and  sometimes  remains  permanently  separate.  Occasion- 
ally it  has  been  found  to  extend,  by  several  pieces,  to  the 
hyoid  bone,  thus  forming  the  hyoid  arch.  The  tympanic 
ring  becomes  united  to  the  squamous  portion  about  the  last 
month  of  foetal  life.  Other  changes  are  observed  in  the 
after  development  of  the  temporal  bone,  as  in  the  growth 
of  the  mastoid  cells,  the  extension  of  the  meatus  auditorius 
externus,  the  enlargement  of  the  glenoid  fossa,  and  the 
filling  up  of  the  irregularities  of  the  petrous  portion.  At 
birth  three  pieces  compose  the  temporal  bone,  viz:  the 
squamous  and  zygomatic,  the  mastoid  and  petrous,  and  the 
tympanic. 

Its  articulations  are  with  five  bones.  With  the  parietal 
by  the  superior  border  of  the  squamous ;  with  the  sphenoid 
by  the  anterior,  and  the  occipital  by  the  posterior  border; 
also  with  the  malar  at  the  zygomatic  suture,  and  the  lower 
jaw  in  the  glenoid  cavity. 

Ethmoid  Bone. — (E^J,  a  sieve.)  The  situation  of  the 
ethmoid  bone  is  in  the  large  notch  be-  Fio  42 

tween  the  orbitar  plates  of  the  fron- 
tal bone.  It  enters  into  the  forma- 
tion of  the  nose,  the  orbit  of  the  eye, 
and  the  anterior  base  of  the  cranium. 
It  receives  its  name  from  its  cribri- 
form or  sieve-like  appearance.  Its 
form  is  cuboidal.  Its  surfaces  are 
three,  one  superior  or  cerebral,  and 
two  lateral  or  orbital;  there  is  also 
an  inferior  y  anterior,  and  &  posterior  portion. 

FIG.  42,  ^Ethmoid  Bone,  showing  an  upper  and  posterior  view,  a  Nasal 
lamella.  6  Cellular  portion  or  body,  c  Crista-Galli.  d  Cribriform  plate, 
e  Superior  meatus.  /  Superior  turbinated  bone,  g  Middle  turbinated  bone. 
&  Os-planum.  i  Surface  for  olfactory  nerve. 


190  BONES  OF  THE  CRANIUM. 

The  superior  surface  is  the  cribriform  plate.  It  is  of  an 
oblong  shape,  and  perforated  with  many  foramina  for  the 
passage  of  the  first  pair  or  olfactory  nerves.  Along  the 
central  part  of  this  surface  there  is  an  eminence,  the  crista 
galli,  to  which  the  falx  major  is  attached.  On  either  side 
of  this  crest  is  a  deep  furrow  for  lodging  the  bulbs  of  the 
olfactory  nerves;  and  at  the  anterior  part  of  this  furrow, 
close  to  the  crest,  is  a  narrow  slit  which  gives  passage  to 
the  nasal  branch  of  the  ophthalmic  nerve.  The  crista 
galli,  at  its  anterior  portion,  projects  into  two  little  pro- 
cesses or  alee  which  connect  it  with  the  frontal  bone. 

From  the  under  surface  of  the  cribriform  plate,  along  the 
middle  line,  descends  the  nasal  lamella  or  vertical  septum. 
This  is  a  broad  plate  of  bone,  thick  before  where  it  joins  the 
nasal  bones  and  the  nasal  process  of  the  frontal  bone,  thick 
behind  and  above  where  it  unites  with  the  sphenoid,  and 
thin  below  where  it  joins  the  vomer  and  nasal  cartilage. 
Upon  the  sides  of  this  nasal  septum  are  seen  canals  ending 
in  grooves,  some  oblique  and  others  vertical,  for  transmit- 
ting the  olfactory  nerves.  Upon  each  side  of  this  septum 
is  the  roof  of  the  nostril;  and  upon  either  side  are  also  ob- 
served two  irregular  bones,  the  superior  and  middle  turbi- 
nated  or  spongy.  Next  to  these  is  a  range  of  cells;  and 
upon  the  outside  of  this  again  an  external  surface,  smooth 
and  plane,  the  os-planum,  and  forming  the  internal 
plate  of  the  orbit  of  the  eye.  The  superior  and  middle 
turbinated  bones  are  very  thin  and  spongy  scrolls  or  curved 
laminge  of  bone,  the  one  above  the  other — the  upper  con- 
taining the  superior  meatus,  the  lower  having  the  middle 
meatus,  and  being  the  more  curved  and  the  larger  of  the 
two. 

The  ethmoid  cells  lie  between  the  turbinated  bones  and 
the  os-planum  and  uriguis,  or  between  the  nasal  and  orbi- 
tal surfaces,  being  bounded  above  by  the  cribriform  plate. 
They  are  twelve  or  fourteen  in  number,  and  are  divided,  by 
a  bony  partition,  into  an  anterior  and  posterior  set.  The 
posterior  communicate  with  the  superior  meatus,  and  are 
small,  and  one  of  the  upper  sometimes  opens  into  the  sphe- 


BOXES  OF  THE  CRANIUM. 


191 


FIG.  43— A 


FIG.  43— B  j 


noid  cells.  The 
anterior  are  more 
numerous  and 
larger;  they  open 
into  the  middle 
meatus,  and  one 
of  the  most  an- 
terior cells  forms 
a  kind  of  infun- 
dibulum  which 
opens  above  into 
the  frontal  si- 
nus, and  ends 
below  in  front 
of  the  maxilla- 
ry sinus  or  an- 
trum  Highmori- 
anum.  The  pitu- 
itary membrane 
extends  from  the 
nose,  and  lines 
the  whole  of  the 
cells.  Its  struc- 
ture is  mostly 

compact,  consisting  of  very  thin  brittle  plates  of  bone;  the 
spongy  tissue  is  found  in  the  crista-galli  and  turbinated 

FIG.  43,  A  represents  cerebral  surface  of  the  Sphenoid  Bone.  1  1  Lesser 
wings  or  alae  minores.  2  2  Upper  extremity  of  greater  wings.  3  ^Ethmoid 
spine.  4  Optic  foramen.  5  Anterior  clinoid  process.  6  Posterior  clinoid. 
7  Sphenoidal  fissure  or  foramen  lacerum  anterius.  8  Foramen  rotundum.  9 
Foramen  ovale.  10  Foramen  spinale.  11  Styloid  process.  12  External 
pterygoid  process.  13  Internal  pterygoid  process.  14  Pterygoid  foramen.  15 
Articular  surface  for  cuneiform  process  of  occiput.  16  Sella  turcica. 

FIG.  43,  B  represents  the  anterior  and  inferior  surface  of  the  Sphenoid,  a  a 
Lesser  wings  of  ingrassias.  6  6  Greater  wings,  c  jEthmoidal  spine,  d  Azygos 
process,  e  e  Sphenoidal  cells.  // Posterior  clinoid  processes,  g  g  Sphenoidal 
fissure,  h  h  Foramen  rotundum.  i  i  Cavities  for  the  middle  lobes  of  the 
cerebrum,  j  j  Surface  for  the  temporal  muscle,  k  k  Styloid  process.  I  I 
External  pterygoid  process,  m  m  Internal  pterygoid  process,  n  Pterygoid 
foramen,  o  o  Articular  surface  for  the  frontal  bone,  p  Sella  turcica. 


192  BONES  OF  THE  CRANIUM. 

portions.  Its  development  takes  place  from  three  centres  of 
ossification,  one  for  the  middle  septum,  and  one  for  each, 
lateral  half.  Ossification  commences  first  in  the  lateral 
portions,  about  the  fifth  month,  (seen  in  the  os-planum 
first.)  The  middle  part  is  not  ossified  till  after  birth,  and 
the  cells  are  not  complete  till  about  the  fifth  or  sixth  year. 
Before  this  period  they  are  Ml,  solid,  and  entirely  cartila- 
ginous. It  is  articulated  with  two  bones  of  the  cranium — 
the  frontal  and  sphenoid,  and  11  of  the  face,  viz:  the  2 
superior  maxillary,  2  lachrymal,  2  nasal,  2  palate,  2  inferior 
turbinated,  and  the  vomer. 

Sphenoid  Bone — (o$qv,  a  wedge.)  The  Sphenoid  bone  re- 
ceives its  name  from  the  manner  in  which  it  is  wedged  in 
or  surrounded  by  all  the  bones  of  the  cranium.  Its  situa- 
tion is  at  the  base  of  the  cranium,  stretching  transversely 
from  side  to  side.  Its  form  has  been  compared  to  the 
bat,  to  which  there  is  some  resemblance,  when  the  ethmoid 
is  attached.  It  is  divided  into  a  body  and  processes.  The 
processes  constitute  the  wings  and  feet  of  the  bat. 

The  body  occupies  the  centre  of  the  bone,  and  presents 
upon  its  anterior  surface  the  azygos  process,  which  articu- 
lates with  the  superior  end  of  the  vomer.  A  small  groove 
for  vessels  is  seen  on  each  side  of  this  process.  The  poste- 
rior surface  is  flat  and  rough,  for  articulation  with  the 
cuneiform  process  of  the  occipital  bone.  On  the  superior 
surface  there  is  a  deep  cavity  called  the  sella  turcica.  This 
is  perforated  by  foramina  for  the  passage  of  vessels,  and 
lodges  the  pituitary  gland.  It  is  bounded  by  a  thin  plate 
of  bone  which  rises  almost  perpendicularly  at  its  posterior 
part,  and  terminates  in  two  processes  called  the  posterior 
dinoid,  to  which  the  tentorium  is  attached. 

At  the  anterior  part  of  the  sella  turcica  is  an  eminence 
called  the  olivary,  where  is  also  seen  a  groove  marking  the 
course  of  the  optic  nerves.  The  sides  of  the  sella  turcica, 
are  grooved  for  the  internal  carotid  artery. 

From  the  superior  and  outer  extremities  of  the  body, 
proceed  transversely  outwards,  two  long  and  thin  pro- 
cesses called  the  alce-minores 3  the  lesser  wings  or  apopJiyses 


BONES  OF  THE  CRANIUM.  193 

of  Ingrassias.  These  end  in  a  point  and  mark  the  position 
of  the  fissure  of  Sylvius,  or  the  division  between  the  ante- 
rior and  middle  lobes  of  the  cerebrum.  These  lesser  wings 
have  processes  projecting  backwards  towards  the  posterior 
clinoid,  and  sometimes  uniting  with  them,  called  the  an- 
terior clinoid  processes.  These  are  thick  tubercles,  and  have 
in  their  base  a  large  foramen  for  transmitting  the  optic 
nerve  and  ophthalmic  artery. 

From  the  posterior  and  inferior  part  of  the  sides  of  the 
body,  proceed  outwards,  upwards,  and  forwards,  the  alee- 
majores  or  greater  wings.  These  processes  present  three 
surfaces,  an  Anterior  or  orbital,  an  external  or  temporal,  and 
an  internal  or  cerebral.  The  orbital  surface  or  process ,  assists 
in  forming  the  outer  wall  of  the  orbit,  is  smooth  and  some- 
what square.  The  temporal  surface  or  process  is  divided  by 
a  transverse  ridge,  called  the  crest,  into  two  portions,  that 
above  the  crest  helping  to  form  the  temporal  fossa,  that 
below  entering  into  the  formation  of  the  zygomatic  fossa. 
The^  inner  or  cerebral  surface  is  concave,  and  with  the 
temporal  bone,  receives  the  middle  lobe  of  the  cerebrum. 

From  the  junction  of  the  greater  wings  with  the  body, 
descend  the  pterygoid  processes.  Each  process  is  divided 
into  an  external  and  an  internal  plate.  The  external  plate 
has  the  pterygoideus  externus  muscle  attached  to  its  outer 
side,  and  the  pterygoideus  internus  to  its  inner  side.  The 
internal  plate  ends  in  a  curved  hook-like  process,  called  the 
hamular  process,  is  covered  by  a  bursa,  and  over  it  the  tendon 
of  the  circumflexus  palati  muscle  plays.  Between  the  two 
plates  is  the  pterygoid-fossa,  occupied  by  the  Eustachian 
tube,  and  the  tensor  palati  muscle.  The  space  between  the 
two  pterygoid  plates  at  their  lower  extremity,  is  filled  by 
the  pterygoid  process  of  the  palatine  bone.  Through  the 
base  of  the  pterygoid  process  runs  the  Vidian  canal,  which 
gives  passage  to  the  pterygoid  branch  of  the  fifth  pair  of 
nerves. 

The  angle  between  the  squamous  and  petrous  portions  of 
the  temporal  bone  is  occupied  by  a  process  called  the  spi- 
nous,  which  projects  from  the  posterior  part  of  each  wing, 
13 


194  BONES  OE  THE  CRANIUM. 

curving  downwards  and  outwards.  To  it  are  attached  the 
internal  lateral  ligament  of  the  lower  jaw,  the  laxator 
tympani,  and  the  tensor  or  circumflexus  palati  muscles. 

This  hone  has  a  number  of  foramina.  Beginning  in  front 
and  proceeding  backwards,  we  observe,  first,  at  the  root  of 
the  lesser  wings,  the  foramen  opticUm  for  the  optic  or  nerves 
of  sight;  second,  the  foramen  rotundiim,  in  the  base  of  the 
greater  wing,  where  it  joins  the  body.  This  opens  into  the 
pterygo-maxillary  fossa,  and  transmits  the  superior  max- 
illary nerve.  Behind  it,  about  half  an  inch,  is  the  foramen 
ovale,  which  gives  passage  to  the  inferior  maxillary  nerve; 
and  a  little  posterior  to  this  again  is  a  small  opening,  the 
foramen  spinale,  through  which  passes  the  middle  menin- 
geal  artery.  Between  the  lesser  and  greater  wings  is  a  long 
slit,  the  foramen  lacerum  superius  or  orbitale,  wide  inter- 
nally, narrow  externally,  and  transmitting  the  third,  the 
fourth,  the  first  branch  of  the  fifth,  and  the  sixth  pair  of 
nerves,  together  with  several  filaments  of  the  sympathetic 
nerve  and  the  ophthalmic  vein.  Between  the  posterior 
part  of  the  greater  wing  and  the  petrous  portion  of  the 
temporal  bone  there  is  another  slit,  the  foramen  lacerum 
medius;  and  at  the  base  of  the  pterygoid  process,  as  stated, 
the  Vidian  foramen. 

The  structure  of  the  sphenoid  is  cellular  in  the  body  and 
bases  of  the  processes,  compact  every  where  else.  At  about 
the  age  of  ten  years  the  body  is  hollowed  into  cavities  called 
the  sphenoidal  sinuses.  In  front  of  them  are  two  triangular 
pyramidal  bones,  called,  after  their  discoverer,  the  ossapyr- 
amidalia  Wisterii,  or  the  sphenoidal  turbinated  bones.  The 
base  of  each  of  these  is  anterior,  and  connects  with  the  eth- 
nioidal  bone  and  its  cells;  the  apex  is  posterior,  and  unites 
with  the  sphenoidal  sinuses.  These  pyramids  of  Wistar 
are  found  to  be  fused  into  the  body  of  the  sphenoid  from 
about  the  fifteenth  to  the  eighteenth  year. 

The  development  of  this  bone  has  been  noticed  to  begin 
from  as  many  as  twelve  points  of  ossification,  viz :  4  for  the 
body,  4  for  the  wings,  2  for  the  pterygoid  processes,  and  2 
for  the  pyramids  of  Wistar.  At  birth  the  sphenoid  is  seen 


GENERAL  REMARKS  ON  THE  CRANIUM.  195 

to  consist  of  three  pieces,,  viz :  1  and  2,  the  greater  wings 
and  pterygoid  processes  of  either  side,  and  3,  the  lesser  wings 
and  body  in  a  single  piece.  The  sphenoidal  spongy  bones, 
or  pyramids  of  Wistar,  belong  also  to  the  latter  piece.  Ossi- 
fication is  noticed  in  the  various  parts  in  the  following 
order,  viz:  1.  In  the  greater  wing  and  external  pterygoid 
process,  about  the  seventh  or  eighth  week.  2.  Lesser  wings 
and  posterior  body,  at  the  close  of  the  second  month.  3. 
Anterior  body,  at  the  end  of  the  third  month.  4.  The  in- 
ternal pterygoid  plate  has  a  separate  ossific  point,  which  is 
stated  to  unite  with  the  external  pterygoid  about  the  middle 
of  the  fourth  month.  The  centres  for  the  posterior  portion 
of  the  body,  and  those  for  the  anterior  and  lesser  wings,  are 
seen  to  unite  first;  then  the  greater  wings  and  pterygoid 
processes.  The  latter  unite  with  the  body  during  the  first 
year;  the  pyramids  of  Wistar  join  it  about  puberty,  at  which 
time  this  bone  becomes  connected  with  the  ethmoid ;  while 
the  body  of  the  sphenoid  joins  the  occipital  bone  between 
the  eighteenth  and  twenty-fifth  years. 

The  sphenoid  is  articulated  with  all  the  bones  of  the  cra- 
nium and  five  of  the  face,  viz:  the  two  malar,  two  palati, 
and  the  vomer. 

GENERAL  REMARKS  ON  THE  CRANIUM. 

Under  the  head  of  the  osseous  tissue  the  different  articu- 
lations were  described.  Synarthrosis  was  stated  to  denote 
the  articulation  of  bones  that  have  no  motion,  and  suture 
the  mode  of  union  between  the  different  bones  of  the  cra- 
nium. 

The  c&ronal,  the  sagittal,  the  lambdoid,  the  squamous,  the 
sphenoid,  and  ethmoid,  constitute  the  principal  sutures. 
(See  Fig.  53.) 

The  coronal  suture  connects  the  anterior  edges  of  the  pa- 
rietal bones  with  the  superior  margin  of  the  frontal,  and 
extends  from  side  to  side  over  the  superior  and  anterior 
surface  of  the  cranium. 

The  sagittal  unites  the  parietal  bones  along  the  median 
line,  and  extends,  from  the  superior  angle  of  the  occipital 


196  BONES  OF  THE  FACE. 

bone  forwards,  to  the  centre  of  the  coronal  suture.  The 
two  extremities  of  this  suture  occupy  the  place  of  the 
anterior  and  posterior  fontanelles. 

The  lambdoidal  connects  the  posterior  edges  of  the  parietal 
with  the  superior  margin  of  the  occipital  hone,  and  extends 
from  the  posterior  end  of  the  sagittal  suture,  on  either  side, 
to  the  mastoid  process  of  the  temporal  bone.  An  extension 
of  this  suture,  under  the  name  of  the  additamentum  sutures, 
lambdoidalis,  reaches  as  far  down  as  the  foramen  lacerum 
posterius,  passing  between  the  mastoid  and  petrous  portions 
of  the  temporal  and  the  occipital  bones.  In  this  suture  we 
find  the  ossa  triquetra  or  wormiana. 

The  sphenoid  suture  is  as  extensive  as  the  very  irregular 
edge  of  the  sphenoid  bone,  connecting  with  it  the  ethmoid, 
frontal,  parietal,  temporal,  and  occipital  bones  of  the  cra- 
nium. 

The  ethmoid  suture  in  the  same  way  surrounds  the 
ethmoid  bone,  uniting  it  with  the  frontal  and  other  bones. 

The  diameters  of  the  cranium  are  thus  given  by  Bichat: 
The  antero-posterior  is  about  five  inches,  and  extends  from 
the  foramen  coecum  in  front,  to  the  internal  occipital  pro- 
tuberance behind.  The  transverse  diameter  is  four  inches 
and  a  half,  and  extends  between  the  bases  of  the  petrous 
portions  of  the  temporal  bones.  The  vertical  diameter  is 
somewhat  less  than  the  transverse,  and  reaches  from  the 
middle  of  the  sagittal  suture  to  the  anterior  edge  of  the 
foramen  magnum. 

SECTION   II. 
BONES  OF  THE  FACE. 

The  Superior  Maxillary  Bones — (ossa  maxillaria  superi- 
ora.)  The  superior  maxillary  is  the  principal  and  largest 
bone  of  the  face.  It  enters  into  the  formation  of  the  orbit, 
the  nose,  the  mouth,  and  the  palate.  It  is  situated  so  as  to 
form  the  greater  part  of  the  front  of  the  face.  Its  shape 
is  somewhat  triangular,  though  very  irregular.  *The  two 
taken  together  are  symmetrical,  each  lateral  portion  com- 


BONES  OP  THE  FACE.  197 

ing  in  contact  upon  the  median  line.  It  is  divided  into 
body  and  processes.  The  body  presents  five  surfaces  for 
examination.  1,  the  anterior  or  facial ;  2,  the  internal  or 

A  FIG.  44. 


nasal;  3,  the  superior  or  orbital;  4;  the  inferior  or  palatine ; 
5,  the  posterior  or  zygomatic. 

The  anterior  surface  is  concave,  and  called  the  canirie 
fossa.  At  the  upper  part  of  this  fossa  is  the  infra-orbital 
foramen,  for  transmitting  the  infraorbital  vessels  and 
nerve.  From  the  upper  and  inner  part  of  this  fossa  the 
nasal  process  of  the  superior  maxilla  arises.  It  ascends 
and  forms  the  side  of  the  nose.  Its  superior  edge  is  ser- 
rated and  articulates  with  the  frontal  bone.  Its  anterior 
edge  is  smooth  and  unites  with  the  nasal  bone  and  the 

FIG.  44,  A  represents  an  outer  view  of  the  superior  maxilla  of  the  left  side, 
a  Orbitar  process.  6  Infra-orbitar  canal,  c  Situation  of  the  os-unguis.  d 
Superior  portion  of  lachrymal  canal,  e  Articulating  surface  for  frontal  bone. 
/  Articulating  portion  with  nasal  bone,  g  Anterior  part  of  the  floor  of  the 
nostril,  'h  Point  of  articulation  with  its  fellow,  i  Alveolar  process,  j  Canine 
fossa,  fc  Articulating  surface  for  the  malar  bone. 

FIG.  44,  B  represents  an  inner  view  of  the  superior  maxilla  of  the  left  side. 
a  Maxillary  sinus  or  Antrum  of  Highmore.  6  Ductus  ad  nasum.  c  Articular 
point  for  the  frontal  bone,  d  Articular  edge  for  the  nasal  bone,  e  Surface 
for  the  nasal  cartilage.  /  Anterior  point  of  the  floor  of  the  nostril,  g  Artic- 
ulating surface  for  the  bone  of  the  right  side,  h  Foramen  incisivum.  i  Pala- 
tine process,  j  Articulating  edge  for  the  palate  bone,  fe  Anterior  articulating 
ridge  for  inferior  turbinated  bone.  I  Articular  surface  for  the  palate  bone 
behind,  m  Surface  for  the  nasal  portion  of  the  palate  bone,  n  Surface  for 
the  orbitar  plate  of  the  palate  bone,  o  Termination  of  nasal  duct. 


198  BONES  OP  THE  FACE. 

alar  cartilage.  The  posterior  is  round,  and  forms  the  inner 
border  of  the  orbit,  and  immediately  posterior  to  this  bor- 
der is  a  deep  groove,  the  lachrymal  fossa,  for  the  nasal  duct. 
Its  anterior  surface  has  the  orbicularis  palpebarum  and 
levator  labii  superioris  alceque  nasi  muscles  attached  to  it. 
Its  internal  surface  forms  part  of  the  nares.  The  canine 
fossa  is  bounded  externally  by  a  rough,  serrated  surface, 
the  malar  process,  which  is  concave  and  smooth  behind  for 
receiving  the  temporal  muscle. 

From  between  the  nasal  and  malar  processes,  and  pro- 
jecting backwards,  so  as  to  form  the  floor  of  the  orbit,  is 
the  superior  or  orbital  surface  or  process.  This  surface  has 
a  triangular  form;  its  base  is  internal  and  connected  with 
the  unguiform,  ethmoid,  and  palate  bones.  Its  posterior 
border  helps  to  form  the  splieno-maxillary  fissure.  Its  ex- 
ternal unites  with  the  malar  bone,  and  its  middle  surface 
is  channeled  into  a  canal,  the  infra-orbital  canal,  which 
terminates  in  the  infra-orbital  foramen.  This  process  is  a 
very  thin  plate  of  bone  forming  the  roof  of  the  antrum  as 
well  as  the  floor  of  the  orbit.  The  infra  orbital  canal,  at 
its  anterior  part,  divides  into  a  smaller  canal,  the  anterior 
dental,  which  descends  in  the  anterior  wall  of  the  antrum 
to  the  anterior  alveoli. 

The  posterior  surface  of  the  superior  maxillary  bone  is 
posterior  and  below  the  orbital.  Its  most  prominent  feature 
is  the  tuberosity,  which  is  larger  in  the  young  subject,  as  it 
then  contains  the  last  molar  tooth,  and  has  three  or  four 
small  foramina,  called  the  posterior  dental  canals,  which 
lead  to  the  posterior  alveoli,  and  transmit  to  the  molar 
teeth  the  posterior  dental  nerves  and  arteries.  The  infe- 
rior portion  of  the  tuberosity  presents  a  rough  surface  for 
articulation  with  the  palate  bone,  and  above  and  to  the 
inner  side  of  this  point  of  articulation,  is  a  smooth  canal, 
which  forms  a  portion  of  the  posterior  palatine  canal. 

The  inferior  or  palatine  surface  of  the  upper  jaw  consti- 
tutes the  floor  of  the  nostrils  and  the  roof  of  the  mouth, 
which  corresponds  in  situation  to  the  inter-maxillary  bones 
of  inferior  animals. 


BONES, OF  THE  FACE.  199 

To  the  practical  dentist,  Mr.  Nasmyth  uses  the  follow- 
ing strong  language  in  reference  to  these  bones :  "These 
bones  serve  most  importantly  to  render  the  upper  jaw 
pliant  during  the  actions  of  the  mouth  in  the  early  years 
of  life,  and  they  are  also  of  high  account  in  promoting  by 
their  growth  the  latitude  necessary  for  the  proper  arrange- 
ment of  the  teeth.  As  a  means  also  of  preventing  concus- 
sion of  the  teeth,  they  are  valuable  accessories  in  the 
mechanism  of  the  mouth."  He  thus  describes  their  anat- 
omy:  aln  the  foetal  skull,  at  the  point  of  junction  of  the 
posterior  with  the  middle  third  of  the  foramen  incisivum, 
a  fissure  may  be  observed,  which  passes  upwards  into  the 
anterior  palatine  canal  on  each  side,  and  may  be  traced 
onwards  to  the  floor  of  the  nasal  cavity.  Having  reached 
the  latter  situation,  it  inclines  obliquely  backwards  and 
outwards  for  the  distance  of  about  a  line,  and  then  bends 
forwards  and  upwards  for  a  space  of  two  or  three  lines  to 
the  base  of  the  nasal  process  of  the  superior  maxillary 
bone,  terminating  upon  the  latter  at  one  or  two  lines  below 
the  ridge  for  the  inferior  turbinated  bone.  If  the  foramen 
incisivum  be  again  examined,  another  fissure  will  be  ob- 
served on  the  oral  surface  of  the  palate,  passing  directly 
outwards  to  the  alveolus  of  the  canine  tooth,  and  curving 
gently  backwards  in  its  course.  The  portion  of  bone  which 
lies  anterior  to  these  fissures  on  each  side,  and  which  sup- 
ports the  incisor  teeth,  is  the  inter-maxillary  bone."* 

This  surface  is  also  called  the  palatine  process  of  the 
superior  maxillary  bone.  It  is  smooth  and  concave  above, 
where  it  forms  the  nares,  and  rough  below  where  it  forms 
the  mouth.  Its  anterior  boundary  is  very  thick,  and  con- 
stitutes the  alveolar  arch  and  processes. 

This  arch  has  eight  conical  cavities  for  the  teeth,  and 
when  united  with  its  fellow,  completes  the  circle  and  con- 
tains sixteen  in  all.  The  cavities  are  separated  by  parti- 
tions of  dense  cellular  tissue,  and  have  their  shape  corre- 
sponding to  the  variety  of  teeth  they  accommodate.  The 
walls  of  these  cavities  form  the  alveolar  processes.  The 

*  Nasmyth's  late  Researches. 


200  BONES  OF  THE  FACE. 

alveolus  of  the  central  incisor  has,  according  to  Mr.  Nasmyth, 
the  septum  between  it  and  its  fellow  twice  as  thick  as  that 
of  the  other  teeth;  its  antero-posterior  diameter  one-third 
greater  than  at  the  sides,  and  its  lateral  diameter  one  third 
greater  in  front  than  behind.  Its  anterior  wall  is  so  thin 
as  to  be  sometimes  incomplete. 

The  alveolus  of  the  lateral  incisor  has  less  depth  than  the 
central,  its  septum  between  the  latter  is  not  so  thick  as 
between  it  and  the  canine,  its  posterior  wall  is  thicker  than 
the  anterior,  and  its  antero-posterior  diameter  is  greater 
than  the  lateral. 

The  alveolus  of  the  canine  ascends  above  the  level  of  the 
roof  of  the  mouth,  and  is  the  deepest  of  all  the  alveoli ; 
it  corresponds  to  the  anterior  wall  of  the  maxillary  sinus, 
is  of  oval  form  as  the  incisors,  and  has  its  antero-posterior 
diameter  about  one  tenth  greater  than  the  latter,  and  look- 
ing backwards. 

The  alveolus  of  the  first  bicuspid  has  its  inferior  part 
partitioned  into  two  cavities  for  the  roots,  the  external 
being  the  larger,  while  its  middle  is  found  narrowed.  Its 
depth  is  equal  to  the  second  bicuspid,  but  not  so  great  as 
the  canine,  and  the  septum  between  it  and  the  latter  is  not 
so  great  as  that  separating  it  from  the  second  bicuspis. 

The  alveolus  of  the  second  bicuspis  is  not  narrowed  in  its 
middle  as  the  latter,  nor  divided  by  a  middle  septum  into 
cavities,  and  its  form  is  oval. 

The  alveolus  of  the  first  molar  is  divided  into  three  cavi- 
ties, two  of  which  are  external,  the  other  internal ;  the  in- 
ternal is  the  largest,  and  the  posterior  external  the  smallest, 
hence  a  rule  of  practice  for  entering  the  antrum,  founded 
upon  the  size  and  direction  of  these  cavities,  always  is  to 
select  the  internal  or  anterior  external  cavity  for  this  pur- 
pose; the  internal  cavity  occasionally  looks  to  a  division  of 
itself,  and  is  sometimes  found  to  communicate  with  the  pos- 
terior, in  which  case  only  one  root,  strong  and  broad,  is  seen 
instead  of  two.  This  alveolus  is  not  unfrequently  found  to 
open  into  the  antrum,  on  which  account  it  is  regarded  as 
the  most  suitable  one  for  perforating  the  antrum  of  High- 


BONES  OF  THE  FACE.  201 

more,  as  well  as  presenting  the  most  dependent  position  of 
this  sinus,  though  the  antrum  may  be  entered  from  the 
alveolus  of  either  the  second  or  first  bicuspis,  but  the  direc- 
tion would  have  to  be  obliquely  backwards. 

The  alveoli  of  all  the  molar  teeth  present  the  triple  divis- 
ion for  its  roots,  which  latter  sometimes  very  much  diverge, 
and  then  again,  on  the  contrary,  greatly  converge,  so  much 
as  sometimes  to  present  the  appearance  of  a  single  root. 
Either  too  great  divergence  or  convergence  of  the  roots 
offers  difficulties  to  extraction,  and  especially  so  when  a 
portion  of  the  alveolus  is  embraced. 

The  posterior  edge  of  the  palatine  process  is  thin  and 
serrated  to  join  the  palate  bone — internally  it  is  thick  where 
it  unites  with  its  fellow — and  at  the  anterior  part  of  this 
union  is  the  anterior  palatine  canal,  which  opens  superiorly 
into  the  nostrils  by  two  foramina,  and  inferiorly  on  the 
mouth  by  one,  the  foramen  incisivum. 

At  the  place  of  junction  of  the  palatine  processes,  the 
upper  edge  in  the  nares  is  raised,  and  called  the  nasal  crest, 
which  receives  the  inferior  border  of  the  vomer.  This  crest 
projects  forwards  and  forms  the  nasal  spine,  between  which 
and  the  nasal  process,  the  bone  is  rounded  and  concave, 
forming  the  anterior  nares. 

The  internal  or  nasal  surface. — The  nasal  surface  presents 
a  very  large  opening  situated  between  the  middle  and  lower 
turbinated  bones,  and  leading  into  a  cavity  called  the 
antrum  Higlimorianum,  or  maxillary  sinus.  This  sinus  is 
of  a  triangular  or  pyramidal  shape,  the  base  looking  to  the 
nose,  the  apex  to  the  malar  process.  It  is  bounded  above 
by  the  orbitar  process  of  the  superior  maxillary  bone,  form- 
ing its  roof,  below  by  that  portion  of  the  alveolar  arch  cor- 
responding to  the  first  and  second  molar  teeth,  constituting 
the  floor ;  in  front  by  the  canine  fossa,  and  behind  by  the 
tuberosity.  Its  shape  and  size  vary  much  in  different 
bones.  It  is  lined  by  the  pituitary  membrane  of  the  nose. 
Its  opening  in  the  natural  skeleton  is  much  contracted  by 
the  ethmoid  and  lachrymal  bones  above  and  in  front,  by  the 
inferior  spongy  below,  and  the  palate  bone  behind.  This 


202  BONES  OF  THE  FACE. 

opening,  says  Mr.  Nasmyth,  "presents  much  variety,  both. 
in  direction  and  position,  sometimes  looking  obliquely  for- 
wards, at  others  obliquely  backwards,  and  being  sometimes 
in  the  anterior  and  sometimes  in  the  posterior  portion  of 
the  nasal  process."  It  is  stated  to  be  about  the  diameter  of 
a  crow  quill,  and  when  deprived  of  the  soft  parts,  to  measure 
from  thirty  to  forty  lines  in  circumference.  The  mucous 
membrane  also  diminishes  the  opening.  The  antrum  has 
its  cavity  sometimes  divided  by  septa  into  cells.  Its  roof  has 
the  infra-orbital  canal  running  along  it,  and  terminating 
in  the  infra-orbital  foramen.  This  roof  is  very  thin,  and 
readily  allows  tumors  of  the  antrum  to  project  into  the 
orbit.  The  floor  has  but  a  thin  partition  between  the  roots 
of  the  teeth  and  this  cavity,  so  thin  indeed  in  some  cases, 
that  the  apices  of  the  molar  teeth  are  seen  to  project  into 
the  sinus,  and  hence  this  is  here  regarded  as  the  most  eli- 
gible spot  for  puncturing  the  antrum,  and  drawing  off  any 
purulent  collections  it  may  contain.  By  some,  the  alveolus 
of  the  canine  tooth  is  thought  most  convenient  for  entering 
the  maxillary  sinus. 

The  anterior  and  posterior  walls  of  this  sinus  contain 
the  anterior  and  posterior  dental  canals,  for  transmitting 
the  dental  nerves  and  vessels.  The  opening  of  the  antrum 
communicates,  by  one  or  two  small  oblique  orifices,  with 
the  middle  meatus  of  the  nose,  and  anterior  to  it  is  the 
funnel-shape  tube,  the  infundibulum,  connecting  with  the 
frontal  sinus  and  anterior  ethmoid  cells. 

The  foramina  in  each  superior  maxillary  bone  are  six  in 
number — 2  proper  and  4  common.  The  proper  are  the 
infra-orbital  and  foramen  incisivum.  The  common  are  the 
foramen  of  the  antrum,  the  posterior  palatine,  the  anterior 
nares,  the  opening  into  the  nasal  or  lachrymal  duct,  and 
the  splieno-maxillary  fissure. 

The  number  of  processes  is  eight,  viz:  the  orbital,  nasal, 
the  tuberosity,  the  alveolar,  malar,  palatine,  the  nasal 
spine,  and  the  nasal  crest. 

The  structure  of  the  upper  maxillary  is  thick  and  cellu- 
lar in  its  processes,  and  very  thin,  but  compact  about  the 


BONES  OP  THE  FACE.  203 

antrum,  and,  though  the  largest  of  all  the  bones  of  the  face, 
is  nevertheless  exceedingly  light,  on  account  of  the  great 
size  of  the  antrum. 

Its  development  is  not  agreed  on  among  anatomists.  Six 
centres  of  ossification  are  enumerated,  viz:  one  for  the 
body  and  one  for  each  of  the  processes,  nasal,  malar  and 
palate,  and  two  for  the  alveoli.  Ossification,  however, 
begins  very  early,  about  the  end  of  the  first  or  beginning 
of  the  second  month  of  fcetal  life,  in  the  alveolar  arch. 
The  anterior  palatine  portion  remains  distinct  for  two  or 
three  years,  and  is  called  the  os-incisivum  or  inter-maxillary, 
and  represents  the  permanent  condition  in  some  of  the  in- 
ferior animals.  At  birth  this  bone  has  great  transverse 
breadth,  but  little  height,  owing  to  the  floor  of  the  orbit 

and  the  alveolar  arch  coming  so  close  together,  which  is, 

however,  gradually  remedied  by  the  enlargement  of  the 

antrum  or  maxillary  sinus. 

Its  articulations  are  with  two  of  the  cranium,  the  frontal 

and  ethmoid,  and  seven  of  the  face,  viz:  the  palate,  the 

malar,  nasal,  lachrymal,  inferior  turbinated,  vomer  and 

its  fellow. 

Palate    Bones — (ossa 

palati.)     The  situation  of 

the  palate  bones  is  at 

the  posterior  part  of  the 

nares.  They  contribute  to 

form  the  floor  of  the  or- 
bit, the  side  of  the  nose, 

and  the  palate.   They  are 

symmetrical.  The/bra  is 

irregular,  though  it  has 

FIG.  45,  A  represents  a  posterior  view  of  the  Palate  Bone,  a  Nasal  surface 
horizontal  plate.  6  Nasal  surface  of  ascending  plate,  d  Articulating 
border  for  its  fellow,  c,  fc,  I  Pterygoid  process.  /  Process  formed  by  junc- 
tion with  its  fellow,  g  Horizontal  articulating  ridge  for  inferior  turbinated 
bone,  h  Spheno  palatine  foramen,  t  Orbital  process,  j  Sphenoidal  process. 

FIG.  45,  B  represents  ascending  plate  of  Palate  Bone,  on  its  spheno-maxil- 
lary  surface,  a  Articulating  surface  with  superior  maxillary  bone.  6  Poste- 
rior palatine  canal,  c  Spheno-palatine  foramen,  d  Spheno-maxillary  face. 
t  Orbital  face.  /Maxillary  face,  g  Sphenoidal  process,  h  Pterygoid  process. 


204  BONES  OF  THE  FACE. 

some  resemblance  to  the  letter  L.  The  palate  bone  is 
divided  into  two  portions,  the  horizontal  or  palatine  and  the 
vertical  or  nasal  portion.  The  horizontal  portion  is  quadri- 
lateral, and  forms  the  posterior  part  of  the  hard  palate.  Its 
upper  surface  is  concave  from  side  to  side,  and  forms  the 
posterior  nares,  and  where  it  unites  with  its  fellow  there 
is  a  crest  to  connect  with  the  vomer.  This  crest  continues 
backwards  into  a  projecting  process,  constituting  the  poste- 
rior nasal  spine,  to  which  the  azygos  uvulae  muscle  is  at- 
tached. The  lower  surface  of  the  horizontal  plate  is  rough 
and  completes  the  arch  of  the  palate.  Its  anterior  edge  is 
serrated  obliquely  and  rests  upon  the  palatine  process  of 
the  superior  maxillary.  Its  posterior  edge  is  thin  and  con- 
cave and  gives  attachment  to  the  velum  palati. 

The  vertical  or  nasal  plate  rises  perpendicularly  from  the 
horizontal,  and  is  thin  and  broad;  it  presents  two  surfaces, 
an  external  and  internal,  and  two  edges,  an  anterior  and 
posterior.  The  external  surface  is  uneven  and  rough  in 
front  where  it  unites  with  the  superior  maxillary.  It  is 
grooved  into  a  canal — the  posterior  palatine  canal — for  the 
passage  of  the  palatine  vessels  and  nerves.  This  canal  is 
bounded  in  front  by  the  tuberosity.  The  inner  or  nasal 
surface  is  divided  by  a  transverse  ridge  to  which  the  infe- 
rior turbinated  bone  is  articulated.  This  ridge  has  a  de- 
pression above  and  below  it;  the  upper  corresponds  to  the 
middle  meatus,  the  lower  to  the  inferior  meatus  of  the  nose. 
At  the  point  of  junction  of  the  nasal  with  the  horizontal 
plate  is  the  pterygoid  process  or  tuberosity.  It  is  thick,  and 
wedge-shaped,  and  occupies  the  space  at  the  lower  part, 
and  between  the  two  plates  of  the  pterygoid  processes  of 
the  sphenoid  bone.  It  presents  three  surfaces,  two  lateral 
uniting  with  the  pterygoid  plates,  and  one  posterior  and 
concave  forming  part  of  the  pterygoid  fossa.  One  or  two 
small  foramina  perforate  this  process  from  the  palatine 
canal.  At  the  superior  extremity  of  the  nasal  plate  are 
seen  two  processes,,  the  orbital  and  sphenoidal.  The  orbital 
is  anterior  and  the  larger  of  the  two  ;  it  is  triangular  and  is 
situated  in  the  most  posterior  part  of  the  floor  of  the  orbit, 


BONES  OF  THE  FACE.  205 

and  is  united  by  its  internal  edge  to  the  ethmoid,  by  its 
anterior  edge  to  the  superior  maxillary,  and  by  its  posterior 
to  the  sphenoid  bone.  The  sphenoidal  process  is  smaller, 
and  posterior  to  the  orbital.  Its  external  lateral  surface 
assists  in  forming  the  spheno-maxillary  fossa;  its  internal 
helps  to  form  the  nares,  and  its  superior  articulates  with 
the  sphenoid  bone.  Both  of  these  processes  are  cellular 
and  communicate  with  the  cells  of  the  sphenoid  and  eth- 
moid. They  are  separated  by  a  large  opening,  the  spheno- 
palatine  foramen,  which  gives  passage  to  the  spheno-palatine 
nerve  and  artery. 

The  palate  bone  has  four  foramina,  one  proper  and  three 
common.  The  posterior  palatine  is  the  proper,  and  the 
spheno-palatine,  the  pterygo-maxillary  canal,  and  the 
spheno-maxillary  fissure  are  the  common. 

Its  processes  are  seven  in  number,  the  nasal,  palate, 
pterygoid,  orbital,  sphenoidal,  posterior  nasal  spine  and 
crest.  Its  structure  is  mostly  compact  and  thin,  except  in 
the  processes.  Its  development  is  by  a  single  centre  of  ossi- 
fication, about  the  middle  of  the  second  month,  at  the  point 
of  union  of  the  horizontal  and  vertical  plates.  It  is  articu- 
lated with  the  sphenoid  and  ethmoid  of  the  cranium,  and 
with  four  of  the  face,  the  superior  maxillary,  vomer,  infe- 
rior turbinated,  and  its  fellow. 

Malar  Bones — (ossa-malarum.)    The  malar  or  cheek  bones 
are  in  pairs,  and  occupy  a  prominent  situation  on  each  side 
of  the  face,  at  the  outer  and  under  portion       FIG.  46. 
of  the   orbit.     Their  form  is   quadrilateral. 
The  external  surface  of  each  is  convex,  and 
has  one  or  more  small  foramina  for  the  passage* 
of  vessels  and  nerves,  and  also  has  the  orbicu- 
laris  palpebrarum  covering  it.  From  the  upper 
part  of  this  bone  ascends  the  superior  or  external  orbital 
process  to  join  the  frontal  bone.    From  its  inner  portion 

FIG.  46  represents  an  internal  view  of  the  right  Malar  Bone,  a  Superior  or 
external  orbital  process  to  join  the  frontal  bone.  6  Orbitar  process,  c  Malar 
foramina,  d  Maxillary  process,  t  Lower  edge  of  the  malar  bone.  /Zygo- 
matic  process,  g  Posterior  concave  surface,  h  External  edge. 


206  BONES  OF  THE  FACE. 

is  the  maxillary  process  whicli  articulates  with,  the  maxil- 
lary bone. 

From  between  these  two  processes  the  bone  is  smooth 
and  round,  and  forms  about  one  third  of  the  lower  and 
outer  margin  of  the  orbit.  From  this  margin  there  projects 
backwards  into  the  cavity  a  thin  plate  of  bone  called  the 
internal  orbital  process.  This  process  joins  the  sphenoid 
and  superior  maxillary  bones,  and  is  notched  posteriorly 
where  it  bounds  in  front  the  spheno-maxillary  fissure.  The 
lower  margin  of  the  cheek  bone  has  the  masseter  muscle 
attached,  and  from  its  posterior  end  proceeds  the  zygomatic 
process,  upon  which  rests  a  similar  process  from  the  tem- 
poral bone.  The  internal  or  posterior  surface  is  concave 
and  smooth,  and  forms  part  of  the  temporal  fossa.  The 
structure  is  thick  and  cellular,  having  a  delicate  compact 
covering. 

The  development  is  from  a  single  point  of  ossification, 
commencing  about  the  latter  part  of  the  second  month.  It 
is  articulated  with  four  bones,  i.  e.  frontal,  sphenoid,  tem- 
poral, and  superior  maxillary. 

Lachrymal  or  Unguiform  Bones,  (pssa-unguis)  The  lach- 
rymal or  tear  bones  are  two  in  number,  and  situated  at 
A.  FIG.  47.  B.  the  anterior  and  inner  portion  of  the 
orbit.  Their  form  is  oval,  and  present 
an  outer  or  orbital  surface,  which  is 
smooth  and  forms  a  portion  of  the  in- 
ner orbit.  At  the  anterior  part  of  this 
surface  is  a  vertical  ridge,  within  which  is  a  deep  groove,  to 
unite  with  a  corresponding  one  in  the  posterior  part  of  the 
nasal  process  of  the  superior  maxillary,  constituting  the 
upper  portion  of  the  nasal  duct  and  lodging  the  lachrymal 
sac.  The  internal  or  nasal  surface  is  rough  and  covers  the 
anterior  ethmoid  cells. 

FIG.  47,  A  represents  right  side  of  os-unguis  or  Lachrymal  Bone,  upon  the  or- 
bitar  or  outer  aspect.  1  Upper  margin.  2  Posterior  margin.  3  Vertical  ridge. 
4  Inferior  margin.  5  Anterior  margin. 

FIG.  47,  B  represents  the  inner  aspect  of  the  same  bone.  1245  Show 
the  same  points  as  in  A.  The  vertical  groove  is  seen  in  this  figure. 


BONES  OF  THE  FACE.  201 

The  structure  of  these  bones  is  entirely  compact,  very 
thin,  transparent,  and  among  the  most  brittle  of  all  the 
bones.  The  development  of  each  bone  is  by  a  single  point 
of  ossification,  which  is  said  to  be  completed  at  the  begin- 
ning of  the  third  month.  The  articulations  are  with  four 
bones,  i.  e.  two  of  the  cranium  and  two  of  the  face.  By  its 
superior  and  posterior  edges  it  is  united  to  the  frontal  and 
ethmoid,  and  by  its  inferior  and  anterior  edges  to  the 
superior  maxillary  and  lower  turbinated  bone. 

Nasal  Bones — (ossa-nasi.)  The  bones  of  the  nose  are 
situated  between  the  nasal  processes  of  the  superior  maxil- 
lary, and  below  the  frontal.  They  are  A-  FlG- 
two  in  number,  and  meet  along  the 
median  line,  so  as  to  form  an  arch 
called  the  bridge  of  the  nose.  This 
arch  is  thick  and  narrow  above,  where 
it  joins  the  frontal  bone,  and  thin  and 
expanded  below  where  it  connects  with 
the  cartilage.  The  external  surface  is 
convex  and  covered  by  the  pyramidalis 
and  compressor  nasi  muscles.  The  internal  surface  is  con- 
cave and  receives  the  nasal  branch  of  the  ophthalmic  nerve. 

The  structure  of  the  nasal  bones  consists  of  two  compact 
tables,  with  intervening  diploe.  Their  development  takes 
place  by  a  single  point  of  ossification  about  the  end  of  the 
second  month.  The  articulation  is  with  four  boneg,  i.  e. 
the  frontal  and  ethmoidal  of  the  cranium,  and  the  superior 
maxillary  and  its  fellow  of  the  face. 

Inferior  Turbinated  Bones  —  (ossa  turbinata  inferiora.) 
(Fig.  49.)  The  inferior  turbinated  or  spongy  bones  are 
situated  at  the  lower  and  outer  part  of  the  nares.  Their 

FIG.  48,  B  represents  an  anterior  view  of  the  nasal  bones.  «  Inferior  ex- 
tremity. 5  Articulating  surface  for  its  fellow,  c  Articulating  edge  for  the 
superior  maxillary  bone,  d  Groove  on  inner  side  for  nasal  nerve,  e  Articu- 
lating border  for  frontal  bone.  /  Foramen  for  nutritious  artery. 

FIG.  48,  A  represents  a  posterior  view  of  nasal  bones,  a  Inferior  extremity 
ft  Articulating  margin  for  its  fellow,  c  Articulating  margin  for  superior 
maxilla,  d  Groove  for  internal  nasal  nerve,  t  Articular  border  for  frontal 
bone.  /  Lower  portion  of  groove  for  the  nasal  nerve. 


208  BONES  OF  THE  FACE. 

greater  length  extends  from  before  backwards.  They  are 
two  in  number  and  have  an  irregular  form.  Each  presents 
FIG.  49.  two  surfaces,  an  internal  or  convex, 

and  external  or  concave.  The  superior 
edge  is  united  to  the  maxillary  and 
palate  bones  by  their  transverse  ridges, 
and  from  it  ascends  a  small  pyramidal  process  connecting 
with  the  unguis  to  complete  the  nasal  duct.  The  inferior 
edge  is  free  and  rolled  outwards.  The  anterior  point  forms 
the  inner  wall  of  the  lower  orifice  of  the  nasal  duct.  The 
structure  is  thin,  brittle,  and  filled  with  small  pores.  The 
development  is  by  a  single  point  from  the  centre,  commen- 
cing about  the  fifth  month  of  foetal  life.  The  articulations 
are  with  four  bones,  the  superior  maxillary,  the  lachrymal, 
the  ethmoid  and  palate. 

Vomer — (the  plough-share.)     The  vomer,  a  single  bone,  so 
called  from  its  supposed  resemblance  to  the  plough-share, 
or,  more  properly,  the  coulter  of  the 
FIG.  50.  plough,  is  situated  on  the  median  line 

so  as  to  divide  the  nares.  It  has  two 
^  surfaces,  which  are  lateral,  and  covered 
by  the  pituitary  membrane,  and  four 
edges,  a  superior,  an  inferior,  an  anterior,  and  a  posterior. 
The  superior  is  thick  and  hollow,  and  receives  the  azygos 
process  of  the  sphenoid  bone.  The  inferior  is  long  and  united 
to  the  palatine  crest  of  the  superior  maxillary  and  palate 
bones.  The  anterior  edge  is  grooved  to  receive  the  middle 
septum  of  the  ethmoid  bone  and  nasal  cartilage  ;  while  the 
posterior  is  sharp  and  divides  the  nares  behind.  Its  struc- 
ture is  compact,  thin,  and  transparent.  Its  development  is 
from  a  single  point,  commencing  about  the  end  of  the 
second  month,  at  its  lower  portion.  Its  articulation  is  with 

FIG." 49  represents  the  maxillary  or  outer  aspect  of  the  right  Turbinated 
Bone.  1  2  Posterior  and  anterior  angles  of  the  turbinated  bone.  3  Lachry- 
mal process.  4  Maxillary  process.  5  Lower  margin.  7  Curved  portion  of 
the  maxillary  process. 

FIG.  50  represents  the  yomer  in  profile.  1  2  Superior  edge,  3  Anterior 
edge,  4  Inferior  edge  of  Tomer.  6  Lateral  surface. 


BONES  OP  THE  FACE.  209 

six  bones,  i.  e.  the  sphenoid,  ethmoid,  two  upper  maxillary, 
and  two  palate. 

Inferior  Maxillary  Bone — (os  maxillare  inferius^—The 
inferior  maxilla,  or  lower 
jaw,  is  situated  at  the  lower 
part  of  the  face,  occupying  the 
front  and  sides,  and  extending 
as  far  back  as  the  base  of  the1 
skull.  Its  form  is  semi-circu- 
lar, and  consists  of  a  body  and 
two  extremities.  The  body 
forms  the  central  and  lateral 
portions.  The  central  portion 
is  prominent,  known  as  the  chin,  and  has  a  vertical  ridge 
along  its  median  line,  the  sympliysis  menti,  which  denotes  the 
original  separation -of  this  bone  into  two  symmetrical  parts. 

The  anterior  surface  of  the  chin  often  presents  a  trian- 
gular shape,  the  base  below  having,  at  either  end,  a  promi- 
nent process,  while  the  apex  is  above.  On  either  side  of 
the  symphysis  is  a  depression  for  the  origin  of  the  depres- 
sor labii  inferioris  muscle;  and  external  to  this  is  an  ob- 
lique opening,  the  anterior  mental  foramen,  through  which 
come  out  the  inferior  dental  nerve  and  artery.  On  the 
posterior  part  of  the  chin  the  surface  is  concave,  except  in 
the  middle  line  of  the  symphysis,  where  is  seen  a  chain  of 
eminences.  To  the  upper  one  of  these  is  attached  the  fre- 
num  linguce,  to  the  middle,  the  genio-hyoglossi,  and  to  the 
lower,  the  genio-Jiyoidei  muscles.  On  either  side  of  this 
middle  line,  and  at  the  upper  part,  are  two  depressions  for 
the  sublingual  glands,  and,  at  the  lower  part  likewise,  de- 
pressions for  the  digastric  muscles.  The  lateral  portions 
take  a  direction  outwards  and  backwards;  on  their  exter- 

FIG.  51  represents  the  inferior  Maxillary  Bone,  a  Body  ;  6  Ramus  ;  c  Sym- 
physis menti ;  d  Alveolar  process ;  e  Anterior  mental  foramen  ;  /  Base  ;  g 
Groove  for  the  facial  artery ;  h  Angle ;  i  Posterior  portion  of  ridge  for  the 
mylo-hyoid  muscle ;  j  Coronoid  process  ;  k  Condyle  ;  /  Neck  of  Condyloid  pro- 
cess; m  Posterior  mental  foramen  ;  n.  Groove  for  inferior  maxillary  nerve  ; 
o  Molar  teeth ;  p  Bicuspid  teeth;  q  r  Middle  and  lateral  incisors. 

14 


210  BONES  OF  THE  FACE. 

nal  surface  is  an  oblique  ridge  running  backwards  and 
upwards  to  the  root  of  the  coronoid  process,  to  which  is 
attached  the  depressor-anguli  oris  and  platzsma  in  front, 
and  the  masseter  muscle  behind. 

On  the  internal  surface  is  also  an  oblique  ridge,  called 
the  mylo-hyoid  ridge,  which  gives  attachment  to  the  mylo- 
hyoid  muscle  in  front,  and  the  superior  constrictor  of  the 
pharynx  and  intermaxillary  ligament  behind.  Beneath 
this  ridge  is  a  groove  for  the  mylo-hyoid  nerve,  and  below 
this  an  oblong  depression  for  the  sub-maxillary  gland. 
The  lower  border  of  the  jaw,  called  the  base,  is  thick  and 
rounded.  The  upper  border  is  the  alveolar  arch,  having 
its  alveolar  processes  and  cavities  corresponding  to  the  va- 
riety of  teeth  they  receive.  The  alveolar  cavity  of  the  mid- 
dle incisor  has  its  antero-posterior  diameter  the  broadest, 
and  the  septum  between  it  and  its  fellow  thicker  than  that 
separating  it  from  the  lateral.  The  alveolus  of  the  lateral 
incisor  has  its  opening  wider  in  front  than  behind,  and  is 
described  as  being  indented  on  its  outer  side.  Its  anterior 
wall  is  a  little  convex,  the  posterior  concave,  and  its  late- 
ral septa  thicker  behind  than  in  front. 

The  alveolus  of  the  canine  is  found  to  be  larger  than  that  of 
either  the  incisors  or  bicuspids.  Its  form  is  conical,  with  the 
sides  compressed  and  presenting,  laterally,  a  depression  cor- 
responding to  the  root  of  the  tooth.  Its  anterior  wall  is  said 
to  be  more  prominent  and  thinner  than  any  other  in  the 
dental  arch,  and  looks  backwards  and  downwards,  while 
the  posterior  is  directly  vertical.  The  axis  of  the  canine 
is  forwards  and  upwards,  and  the  opening  of  its  alveolus 
is  said  to  be  twice  the  breadth  in  front  that  it  is  behind. 
Its  form  is  oval. 

The  alveolus  of  the  first  bicuspid  has  its  form  conical,  its 
sides  compressed,  its  outer  surface  flat,  and  its  inner  rather 
concave.  It  is  smaller  than  the  canine,  has  its  opening  oval, 
with  edges  in  front  and  behind  seen  to  be  a  little  indented. 
Its  antero-posterior  diameter  looks  outwards  and  forwards, 
its  vertical  obliquely  inwards. 

The  alveolus  of  the  second  bicuspidh&s  its  vertical  axis  look- 


BONES  OF  THE  FACE.  211 

ing,  says  Mr.  Nasmyth,  downwards  and  backwards  ;  a  fact 
which  he  regards  of  great  practical  moment  in  the  man- 
agement of  the  teeth,  as  a  space  is  thus  gained  of  three  or 
four  lines  hetween  the  roots  of  the  two  bicuspids.  This 
alveolus  is  larger  than  that  of  the  anterior,  hut  less  than 
that  of  the  canine. 

The  alveolus  of  the  first  molar  has  a  partition  dividing  it 
into  an  anterior  and  posterior  cavity — the  anterior  being 
rather  the  larger,  and  the  axes  of  both  looking  backwards. 
The  septum  is  described  as  thickest  in  the  centre,  abound- 
ing with  openings  for  the  passage  of  vessels,  and  has  its 
direction  inwards  and  backwards  from  the  outer  side.  Its 
opening  is  of  a  quadrilateral  form,  having  its  front  margin 
indented. 

The  alveolus  of  the  second  molar  has  also  a  septum 
(occasionally  absent)  dividing  it  into  an  anterior  and  pos- 
terior cavity,  the  anterior  being  the  larger,  and  found  to  be 
somewhat  contracted  in  its  middle  and  "compressed  from 
before  backwards;"  the  posterior  is  oval  and  not  so  deep. 
Its  opening  is  also  quadrilateral. 

The  alveolus  of  the  third  molar  is  always  smaller  and  shal- 
lower than  either  of  the  others,  and  is  found  to  present 
great  variety  both  in  form  and  size.  It  is  seen  sometimes 
divided  into  two  cavities,  and  then  again  having  but  one. 
The  alveoli  of  the  molar  teeth  all  look  outwards,  so  that  the 
crowns  of  these  teeth  have  a  direction  inwards.*  At  the 
posterior  extremity  of  the  lateral  portions  is  the  angle,  which 
is  nearly  a  right  angle  in  the  adult,  but  quite  obtuse  in  the 
foetus,  and  to  which,  on  its  internal  edge,  is  attached  the 
stylo  maxillary  ligament.  From  the  posterior  ends  of  the 
lower  jaw  there  rises,  almost  perpendicularly,  a  process 
called  the  ramus.  This  process  is  square-shaped  and  very 
strong.  It  has  different  angles  at  different  periods  of  life. 
In  the  infant  it  is  nearly  on  a  line  with  the  lateral  portions. 
In  youth  it  is  oblique.  In  the  adult  it  becomes  nearly  ver- 
tical, while  in  old  age  it  again  returns  to  the  infant  state 
Its  external  surface  is  covered  by  the  masseter  muscle 

*  Alexander  Nasmyth's  late  Researches  on  the  Teeth. 


212  BOKES  OF  THE  FACE. 

Its  internal  surface  has,  in  the  centre,  the  posterior  mental 
or  inferior  dental  foramen,  which  transmits  the  inferior 
dental  artery  and  nerve.  This  foramen  is  protected  by  a 
shelf  of  bone  to  which  is  attached  the  internal  lateral  liga- 
ment, and  it  leads  to  a  canal  which  passes  beneath  the 
alveolar  cavities,  with  each  of  which  it  communicates,  and 
conducts  to  the  teeth  their  nerves  and  vessels.  Below  this 
posterior  foramen  is  the  insertion  of  the  pterygoideus  inter- 
nus  muscle.  The  ramus  terminates  above  in  two  processes, 
viz :  the  anterior  or  coronoid,  and  posterior  or  condyloid. 

The  coronoid  process  is  triangular  and  is  surrounded  by 
the  tendinous  insertion  of  the  temporal  muscle.  The  ante- 
rior border  of  the  root  is  grooved  for  the  buccinator  muscle. 
The  condyloid  process  is  oblong  and  has  its  greatest  diam- 
eter looking  obliquely  backwards  and  inwards.  Its  upper 
surface  is  smooth  and  covered  with  a  movable  fibro-carti- 
lage,  intervening  between  it  and  the  glenoid  cavity  of  the 
temporal  bone  with  which  it  articulates.  Around  the  base 
of  the  condyle  there  is  a  contraction  called  its  neck,  to  the 
anterior  and  inner  portion  of  which  the  pterygoideus  exter- 
nus  muscle  is  inserted.  The  curve  between  the  two  pro- 
cesses is  the  sigmoid  notch,  over  which  pass  the  masseteric 
artery  and  nerve. 

The  structure  of  the  lower  jaw  is  compact  externally,  and 
spongy  or  cellular  within.  The  walls  of  the  alveoli  and 
their  partitions  are  also  spongy.  The  interior  of  this  bone 
has  already  been  stated  to  be  traversed  by  the  inferior 
maxillary  or  dental  canal.  This  canal,  commencing  at 
the  posterior  dental  foramen,  gradually  contracts  as  it 
proceeds  forwards  under  the  summits  of  the  alveoli.  At 
the  second  bicuspid  tooth  it  divides  into  two  canals,  the  one 
large,  terminating  at  the  anterior  mental  foramen,  the 
other  small  and  continued  forward  in  the  line  of  the 
original  canal,  to  the  incisor  teeth,  to  which  it  is  dis- 
tributed. 

The  situation  of  this  canal  varies  at  different  periods  of 
life.  In  the  infant,  at  birth,  according  to  Cruveilhier,  it 
occupies  the  lowest  portion  of  the  jaw.  After  second  den- 


ARTICULATION   OF  THE  LOWER  JAW.  213 

tition,  it  is  nearly  on  a  line  with  the  mylo-hyoid  ridge-; 
and  in  old  age,  when  the  teeth  are  lost,  it  runs  along  the 
alveolar  "border.  Its  size  also  varies.  Before  the  appear- 
ance of  the  second  teeth,  and  in  the  foetus,  it  is  observed  to 
be  very  large ;  it  diminishes  in  the  adult,  and  contracts 
still  more  in  old  age. 

The  development  of  the  inferior  maxilla  is  by  two  points 
of  ossification,  one  for  each  lateral  half;  their  common 
point  of  union  being  the  symphysis.  It  and  the  clavicle 
are  the  first  bones  formed.  The  lower  edge  of  this  bone  is 
seen  to  commence  ossifying  about  the  end  of  the  first  month, 
and  about  the  end  of  the  second,  each  half  of  the  bone  pre- 
sents a  groove  common  to  the  dental  canal  and  alveoli. 
Union  of  the  symphysis  occurs  during  the  first  year. 

ARTICULATION   OF  THE  LOWER  JAW. 

It  articulates  with  the  temporal  bones  at  the  glenoid  fos- 
sae, and  with  the  sixteen  lower  teeth.  The  condyles  of  the 
inferior  maxilla  and  that  portion  of  the  glenoid  cavity  of  the 

A  FIG.  52.  B 


temporal  bone,  in  front  of  the  glasserian  fissure,  constitute 
the  bony  portions  which  enter  into  the  movable  articulation 

FIG.  52,  A  represents  an  external  view  of  the  Articulation  of  the  Lower  Jaw. 
a  Zygomatic  arch.  6  Tubercle  of  the  zygoma,  c  Ramus  of  the  lower  jaw. 
d  Mastoid  process  of  the  temporal  bone,  e  External  lateral  ligament.  /  Stylo- 
maxillary  ligament. 

FIG.  52,  B  represents  an  inner  view  of  the  same  articulation,  a  Section 
through  the  petrous  portion  of  the  temporal  bone  and  spinous  process  of  the 
sphenoid,  b  Internal  view  of  part  of  the  body  and  ramus  of  the  lower  jaw. 
c  Interfial  portion  of  the  capsular  ligament,  d  Internal  lateral  ligament. 
e  Point  for  passage  of  the  mylo-hyoid  nerve.  /  Stylo-maxillary  ligament. 


214  ARTICULATION  OP  THE  LOWER  JAW. 

of  the  lower  jaw,  and  which,  are  covered  with  cartilage. 
The  other  elements  of  this  joint  consist  of, 

1.  A  capsular  ligament, 

2.  External  and  internal  lateral  ligaments, 

3.  Interarticular  cartilage, 

4.  Two  synovial  membranes, 

5.  Stylo-maxillary  ligament, 

6.  Intermaxillary  ligament. 

The  capsular  ligament  extends  from  the  glenoid  fissure 
and  zygomatic  eminence  to  the  neck  of  the  lower  jaw.  It 
consists  of  strong  fibres,  though  it  is  deficient  internally 
and  in  front  where  the  external  pterygoid  muscle  is  at- 
tached. This  ligament  is  connected  internally  with  the 
interarticular  cartilage  and  synovial  membranes,  and  ex- 
ternally with  the  external  and  internal  lateral  ligaments. 

The  external  lateral  ligament  extends  from  the  zygomatic 
process  of  the  temporal  bone  at  its  root,  to  the  neck  of  the 
condyle  of  the  lower  jaw,  at  its  outer  side.  It  is  short  and 
narrow,  and  is  regarded  simply  as  a  thickening  of  the  cap- 
sular ligament  upon  its  external  side.  This  ligament  is 
hid  by  the  parotid  gland. 

The  internal  lateral  ligament  extends  from  the  spinous 
process  of  the  sphenoid  bone  to  the  spine,  which  overhangs 
the  posterior  mental  foramen ;  it  is  longer  and  thinner  than 
the  external,  and  serves  to  protect  the  inferior  dental  artery 
and  nerve,  which  are  situated  between  this  ligament  and 
the  bone. 

The  interarticular  cartilage  is  situated  within  the  joint 
and  divides  it  into  two  distinct  cavities,  which  sometimes, 
however,  communicate  by  an  opening  in  the  centre.  This 
cartilage  is  'oval  transversely,  and  consists  of  concentric 
fibres,  very  compact,  and  more  distinct  and  thick  at  the  cir- 
cumference than  at  the  centre.  It  is  attached  to  the  cap- 
sular ligament,  and  by  presenting  a  movable  socket,  is 
believed  to  strengthen  as  well  as  to  guard  against  dislo- 
cations. 

Of  the  two  synovial  membranes,  the  larger  is  superior  and 


GENERAL  REMARKS  ON  THE  SKULL.  215 

covers  the  glenoid  cavity,  the  cartilaginous  portion  of  the 
zygomatic  eminence,  the  upper  surface  of  the  inter  articular 
cartilage,  and  the  capsular  ligament.  The  smaller  synovial 
membrane  covers  the  cartilaginous  surface  of  the  condyle, 
the  lower  surface  of  the  interarticular  cartilage,  and  is 
also  reflected  upon  the  inner  wall  of  the  capsular  liga- 
ment. These  synovial  capsules  are  generally  complete 
sacs,  having  no  communication,  and  their  function  is  to 
secrete  a  fluid  to  lubricate  and  thus  facilitate  the  move- 
ments of  this  joint. 

The  stylo-maxillary  ligament  extends  from  the  styloid 
process  of  the  temporal  bone  to  the  angle  of  the  lower  jaw. 
It  consists  of  a  delicate  aponeurosis,  and  has  but  little  to  do 
with  the  articulation. 

The  intermaxillary  ligament  also  has  little  to  do  with  the 
joint,  and  is  hardly  considered  deserving  the  name  of  a 
ligament  It  is  seen  extending  from  the  external  ptery- 
goid  plate  and  contiguous  portion  of  the  superior  maxilla 
above,  as  an  aponeurotic  band,  to  the  root  of  the  coronoid 
process  of  the  inferior  maxilla  below,  and  forming  a  com- 
mon point  of  attachment  for  the  buccinator  and  superior 
constrictor  muscles  of  the  pharynx.  The  motions  of  this 
joint  consist  of  elevation,  depression,  the  forward,  back- 
ward, and  lateral  movement  performed  by  the  muscles  of 
mastication. 

GENERAL  REMARKS  ON  THE  SKULL. 

Anatomists  distinguish  in  the  skull  five  regions,  an  an- 
terior, a  superior,  an  inferior  and  two  lateral  regions, 
(Fig.  53.)  The  anterior  region  is  the  face,  and  presents 
somewhat  fheform  of  an  oval.  Its  surface  is  very  irregular, 
having  cavities  for  the  accommodation  of  two  of  the  senses, 
seeing  and  smelling.  Its  outline  may  be  traced  by  draw- 
ing a  semi-circular  line  above,  through  the  protuberances  of 
the  frontal  bone,  and  extending  it  laterally  round  the  ex- 
ternal angular  processes  of  the  same  bone,  and  thence  con- 
tinuing it  along  the  outer  margin  of  the  malar  to  the  lower 
jaw,  running  along  its  lower  border.  So  that  the  facial 


216 


GENERAL  REMARKS   ON  THE   SKULL. 


FIG.  53. 


surface  includes  the  bones  of  the  face  with  a  portion  of  the 
frontal  bone. 

In  the  superior  part  of  this  surface,  on  the  median  Iine7 
is  seen  the  nasal  tuberasity,  on  either  side  of  which  are  the 
superciliary  ridges.  Below  these  are  the  superior  orbit- 
ary  margins,  with  the  supra  orbital  holes  at  their  inner 
third;  for  the  transmission  of  the  supra-orbital  nerve  and 

artery.  Below 
the  nasal  tu- 
berosity  is  the 
nasal  spine  of 
the  os  frontis, 
next  are  the 
nasal  bones 
forming  the 
bridge  of  the 
nose ;  on  either 
side  of  which  are 
seen  the  nasal 
processes  of  the 
superior  max- 
**  illary  bones, 
the  internal  an- 
gular processes 
of  the  os  fron- 
tis,  and  still  more  externally  the  openings  of  the  orbits. 
Below  the  ossa  nasi  are  the  anterior  nares,  on  the  inferior 
and  central  margin  of  which  is  the  anterior  nasal  spine, 
and  below  this  again  are  the  symphysis  of  the  upper  jaw 
and  the  alveolar  arch  and  processes. 

On  either  side  of  the  anterior  nares  are  the  canine  fossae 
for  giving  origin  to  the  levator  anguli  oris  muscle ;  above 
this  is  the  infra-orbital  foramen,  transmitting  the  infra- 

FIG.  53  represents  the  Bones  of  the  Cranium  and  Face,  with  a  few  of  the 
sutures.  1  Frontal  bone.  2  Parietal.  3  Temporal.  4  Sphenoidal.  5  Malar. 
6  Superior 'maxillary.  7  Nasal.  8  Vertical  plate  or  septum  of  ethmoid. 
9  Lower  jaw.  11  Lachrymal  bone.  12  Os  planum  of  ethmoid.  13  Super- 
numerary bone.  14  Incisor  teeth.  Between  1  and  2,  Coronal  suture.  Be- 
tween 2  and  3,  Squamous  suture. 


GENERAL  REMARKS  ON  THE  SKULL. 

orbital  vessels  and  nerve ;  and  above  this  again  is  the 
inferior  and  inner  orbitary  margin,  giving  attachment  to 
the  levator-labii  superioris  alasque  nasi,  and  covered  by 
the  orbicularis  palpebrarum  muscle. 

The  malar  bone  forms  the  outer  boundary  of  the  face ; 
and  the  lower  jaiu,  which  projects  forward  into  the  chin, 
and  backward  and  upward  into  the  rami  and  processes,  the 
inferior  boundary. 

The  cavities  of  the  face  are  the  orbits  and  the  nose.  The 
orbits  are  two  hollow  cones  with  their  bases  in  front  and 
their  apex  behind.  The  directions  of  their  axes  are  back- 
wards and  inwards,  and,  if  prolonged,  they  would  inter- 
sect each  other  over  the  sella  turcica,  forming  an  angle  of 
about  90  degrees.  Seven  bones  enter  into  the  composition 
of  each  orbit.  The  roof  is  formed  by  the  orbital  processes 
of  the  frontal  bone  and  the  lesser  wing  of  the  sphenoid.  The 
floor  is  formed  by  the  orbital  processes  of  the  superior  max- 
illary bone  and  of  the  palate  bone,  together  with  a  portion 
of  the  malar.  The  outer  wall  consists  of  the  orbital  sur- 
faces of  the  greater  wing  of  the  sphenoid  and  malar  bones, 
while  the  inner  wall  is  composed  of  the  lachrymal,  the  os- 
planum  of  the  ethmoid,  and  part  of  the  sphenoid. 

Several  foramina  and  openings  communicate  with  the 
orbit.  Behind  are  the  optic  foramen,  giving  entrance  to  the 
optic  nerve  and  ophthalmic  artery,  and  the  foramen  lacerum 
superius  or  orbitale,  or  the  sphenoidal  fissure,  transmitting 
the  third,  fourth,  first  branch  of  the  fifth,  and  the  sixth 
nerves.  At  the  lower  and  outer  portion  of  the  orbit  is  the 
splieno-inaxillary  fissure,  in  which  is  found  the  superior  max- 
illary nerve  and  artery.  There  are  also  some  small  fora- 
mina penetrating  the  malar  bone.  On  the  inner  wall  are 
seen  the  anterior  and  posterior  ethmoidal  foramina — the  for- 
mer giving  passage  to  the  nasal  branch  of  the  ophthalmic 
nerve  and  the  anterior  ethmoidal  artery,  the  latter  to  the  pos- 
terior ethmoidal  artery.  At  the  inner  canthus  is  the  nasal 
duct,  and  in  the  supra-orbital  margin  the  supra-orbital  fora- 
men. The  ball  of  the  eye  with  its  muscles,  vessels,  nerves, 
and  the  lachrymal  gland  and  its  ducts,  are  all  contained 
within  the  orbits. 


218 


GENERAL  REMARKS  ON  THE  SKULL. 


The  nose  or  nasal  fossce  are  two  cavities  situated  upon 
either  side  of  the  median  line,  and  separated  by  the  vomer 
and  middle  septum  of  the  ethmoid.  They  are  bounded  ante- 
riorly and  superiorly  by  the  nasal  bones ,  cribriform  plate  of 
the  ethmoid  and  sphenoid  bones,  infer iorly  by  the  palatal 
processes  of  the  superior  maxillary  and  palate  bones,  and 
externally  by  the  nasal  processes  of  the  superior  maxillary, 
lachrymal,  ethmoid,  palate,  and  inner  plate  of  the  pterygoid 
process  of  the  sphenoid. 

Each  fossa   contains  three  turbinated  bones,  a  superior, 
middle   and  inferior,  with   three  corresponding   meatuses. 
FIG.  54.  The  superior  meatus  communi- 

cates with  the  posterior  eth- 
moidal  and  sphenoidal  cells 
and  the  spheno-palatine  fora- 
men. The  middle  meatus,  sit- 
uated between  the  upper  and 
lower  spongy  bones,  looks  into 
the  antrum,  and  connects  with 
the  anterior  ethmoid  cells  and 
frontal  sinuses. 

The  inferior  region  or  base 
of  the  skull  is  v.ery  irregular 
and  reaches  from  the  nasal 
process  of  the  os  frontis  to  the 
external  occipital  protuberance. 
It  is  divided  into  three  re- 
gions, an  anterior,  middle  and  posterior.  The  anterior  ex- 
tends from  the  superciliary  arches  of  the  frontal  bone  to 
the  pterygoid  processes  of  the  sphenoid,  and  includes  the 

FIG.  54  represents  an  external  view  of  the  Base  of  the  Cranium,  aa  Hard 
palate.  &  Foramen  incisivum.  c  Palate  plate  of  the  palate  bone,  d  Point 
for  attachment  of  azygos  uvulae  muscle,  e  Vomer  dividing  posterior  nares. 
/  Internal  or  pterygoid  process,  g  Pterygoid  fossa,  h  External  pterygoid 
Process,  i  Temporal  fossa,  j  Cuneiform  process  of  occipital  bone,  k  Fo- 
ramen magnum.  I  Foramen  ovale.  m  Foramen  spinale.  n  Glenoid  fossa, 
o  Meatus  auditorius  externus.  p.  Foramen  lacerum  anterius.  q  Foramen 
caroticum.  r  Foramen  lacerum  posterius.  s  Styloid  process,  t  Stylo  mas- 
toid  foramen,  u  Mastoid  process,  v  Condyles  of  occipital  bone,  w  Poste- 
rior condyloid  foramen. 


GENERAL  REMAKES  ON  THE  SKULL.  219 

nasal  spine  and  orbital  plates  of  the  os-frontis,  with  the  inter- 
nal and  external  angular  processes,  and  the  ethmoid  bone. 

The  middle  division  reaches  from  the  pterygoid  to  the 
styloid  processes,  and  includes  the  pterygoid,  azygos,  and 
spinous  processes  of  the  sphenoid  bone,  the  glenoid  cavities, 
and  petrous  points  of  the  temporal,  with  the  cuneiform  pro- 
cess of  the  occipital  bone.  In  this  region  are  found  the 
foramina  ovalia,  spinalia,  corotica,  glenoidea,  and  auditoria 
externa.  The  posterior  division  reaches  from  the  styloid 
processes  to  the  external  occipital  protuberance,  and  includes 
the  styloid,  vaginal  processes,  the  two  condyloid,  and  the 
two  mas toid  processes,  with  their  digastric  fossa,  ihe  jugu- 
lar ridges,  the  inferior  and  superior  transverse  ridges,  the 
protuberance,  and  the  depressions  of  the  occipital  bone. 

The  foramina  in  this  division  are  the  foramen  magnum, 
the  anterior  and  posterior  condyloid,  the  stylo-mastoid,  the 
posterior  mastoid,  the  foramen  lacerum  posterius,  and  the 
aqueductus  cochlea?. 

The  to?  lateral  regions  are  divided  each  into  three  por- 
tions, an  anterior  or  temporal,  a  middle  or  squamous,  and 
posterior  or  mastoid.  The  temporal  division  includes  the 
temporal  fossa,  and  is  bounded  in  front  by  the  raaZar  bone 
and  the  external  angular  process  of  the  frontal  bone  ;  above 
by  the  temporal  ridge,  and  below  by  the  zygomatic  arch. 
The  anterior  portion  of  the  squamous  bone,  the  greater  wing 
of  the  sphenoid,  the  malar,  and  a  part  of  the  frontal,  form 
this  division,  which  is  covered  by  the  temporal  muscle. 
The  temporal  fossa  is  continuous  with  the  zygomatic,  which 
latter  is  situated  below  the  zygoma,  between  the  tuberosity 
of  the  superior  maxillary,  and  the  pterygoid  process  of  the 
sphenoid,  and  bounded  externally  by  the  zygoma  and  the 
ramus  of  the  lower  jaw.  The  zygomatic  fossa  contains  the 
external  pterygoid  muscle,  a  portion  of  the  temporal  and 
internal  pterygoid,  with  the  inferior  maxillary  nerve,  in- 
ternal maxillary  artery  and  branches. 

The  squamous  division  is  formed  by  the  squamous  portion 
of  the  temporal  bone  and  is  covered  by  the  temporal  muscle. 
The  mastoid  division  is  posterior,  and  its  most  prominent 


220  GENERAL  REMARKS  ON  THE  SKULL. 

feature,  the  mastoid  process,  has  been  already  noticed  in 
the  description  of  the  base.  The  superior  region,  or  vertex, 
is  smooth  and  marked  off  by  sutures  (Fig.  53,)  already 
detailed. 

The  inner  or  cerebral  surface  consists  of  the  arch  or  vault, 
and  the  base. 

The  vault  presents  along  the  median  line  a  sulcus  for  the 
superior  longitudinal  sinus.  There  are  also  seen  grooves  for 
the  middle  meningeal  artery,  and  depressions  for  the  convo- 
lutions of  the  brain. 

The  base  has  three  divisions,  an  anterior,  middle,  and 
posterior.  The  anterior  division  includes  the  crista  galli  and 
cribriform  plate  of  the  etlimoid  bone,  the  orbital  processes  of 
the  frontal,  and  the  aloe,  minores  of  the  sphenoid.  The 
foramina  of  this  division  are  the  olfactory,  foramen  ccecum, 
and  the  optic. 

The  middle  division,  called  also  the  middle  fossa,  is  situ- 
ated between  the  lesser  wings  of  the  sphenoid  and  the  supe- 
rior ridge  of  the  petrous  bone,  and  bounded  laterally  by  the 
squamous  portion  of  the  temporal.  In  the  centre  or  on  the 
median  line,  where  the  two  fossa3  approach,  is  seen  the 
sella  turcica  bounded  by  its  four  processes,  two  anterior, 
and  two  posterior  clinoid — on  either  side  is  a  groove  for  the 
cavernous  sinus  and  carotid  artery,  and  external  to  this  is 
the  middle  fossa  for  lodging  the  middle  lobes  of  the  cere- 
brum— on  the  anterior  surface  of  the  petrous  bone  are  seen 
a  depression  for  the  Gasserian  ganglion,  the  hiatus  Fallopii, 
and  the  eminences  marking  the  vertical  semi-circular  canals. 

The  foramina  of  this  division  are  the  superior  lacerated, 
the  rotundum,  the  ovale,  the  spinale,  the  middle  lacerated 
foramen,  and  the  hiatus  Fallopii. 

The  posterior  division  extends  from  the  superior  ridge  of 
the  petrous  bone  and  posterior  clinoid  processes,  to  the  trans- 
verse ridge  of  the  occipital.  It  includes  the  posterior  sur- 
face of  the  petrous  bones,  on  which  are  seen  the  internal  au- 
ditory foramina,  and  the  aqueducts  of  the  vestibule.  In  the 
middle  is  the  cuneiform  process,  on  either  side  of  and  between 
it  and  the  petrous  bone  are  the  posterior  lacerated  foramina ; 


GENERAL  DEVELOPMENT  OF  THE  SKULL,        221 

posterior  to  the  cuneiform  process  is  the  foramen  magnum,  and 
behind  this  is  the  occipital  surface  which  presents  two  large 
fossce  for  lodging  the  lobes  of  the  cerebellum.  These  are  sepa- 
rated by  a  vertical  ridge,  to  which  ihefalx  minor  is  attached. 
Where  the  vertical  and  transverse  ridges  intersect,  is  seen 
the  internal  occipital  protuberance,  corresponding  to  the  sit- 
uation of  the  torcular  Heropliili,  or  the  common  point  of 
junction  of  the  great  sinuses  of  the  brain. 

On  either  side  of  this  protuberance  is  the  transverse  ridge 
to  which  the  tentorium  is  attached,  and  below  and  parallel 
with  this  ridge  is  a  deep  groove  which  is  continued  along 
the  inferior  angles  of  the  parietal  and  the  mastoid  portion 
of  the  temporal  bone,  and  finally  end  in  the  foramen  lacerum 
posterius  of  each  side.  This  groove  conducts  the  lateral 
sinuses  out  of  the  brain, 

GENERAL  DEVELOPMENT  OF  THE  SKULL. 

In  the  foetus,  the  upper  part  of  the  face  decidedly  pre- 
dominates, in  consequence  of  the  early  development  of  the 
frontal  bone.  The  middle  portion  or  upper  jaw  is,  on  the 
other  hand,  very  small  from  the  absence  of  the  maxillary 
sinus — so  that  the  floor  of  the  orbit  and  the  alveolar  arch 
almost  meet.  The  alveolar  border  is  prominent,  owing  to 
the  presence  of  the  germs  of  the  teeth. 

The  lower  portion  of  the  face,  consisting  of  the  lower 
jaw,  is  also,  at  this  period,  contracted  in  its  vertical  diam- 
eter, and  like  the  upper  maxilla,  from  the  presence  of  teeth 
germs,  presents  a  similar  prominence  in  its  alveolar  arch. 
The  ethmoid  bone  is  also,  at  this  period,  little  developed 
in  height.  The  transverse  diameter  of  the  face,  on  a  line 
with  the  orbits,  is  great ;  at  the  lower  part,  small. 

In  the  adult,  the  maxillary  sinuses  being  developed,  and 
the  alveolar  arches  being  widened  and  extended,  give  the 
face  the  characteristic  expression  of  this  period  of  life; 
while  in  the  aged,  the  loss  of  the  alveolar  processes  and 
teeth  brings  back  again  the  face  in  a  great  measure  to  the 
foetal  condition.  These  remarks  apply  mostly  to  the  ante- 
rior face.  The  posterior  or  guttural  portion  in  the  foetus  and 


222  ACTIVE  ORGANS  OP  THE  HEAD. 

infant  lias  the  rami  of  the  lower  jaw  very  oblique  instead 
of  vertical,  as  in  the  adult.  The  posterior  nares  and  the 
pterygoid  processes  look  also  obliquely  forward  and  down- 
ward, while  in  the  adult  they  become  vertical  by  the  de- 
velopment of  the  maxillary  sinuses,  carrying  them  back- 
wards. The  palatine  region,  from  the  same  want  of  de- 
velopment in  the  maxillary  sinus  and  forward  obliquity  of 
the  pterygoid  processes,  is  much  shorter  from  before  back- 
wards, than  in  the  adult. 

It  is  thus  seen  how  much  the  configuration  of  the  face 
depends  on  the  presence,  absence,  or  partial  development 
of  these  sinuses. 

The  cranium  is  remarkable  for  its  early  ossification,  which 
commences  first  in  the  vault,  though  at  birth  it  is  found 
more  advanced  in  the  base.  Indeed,  at  this  period,  the 
base  is  firm  and  immovable,  while  the  vault  has  its  bones 
separated  by  intervening  membranes,  which  allow  of  con- 
siderable movement,  so  much  so  that  during  labor  there  is 
always  more  or  less  overlapping  of  the  bones.  It  is  at  this 
period  the  anterior  and  posterior  openings  in  the  cranium, 
called  fontanelles,  are  seen. 


CHAPTEK  II. 

ACTIVE   ORGANS   OF    THE    HEAD. 

THESE  organs  include — 

1.  Organs  of  Digestion. 

2.  Organs  of  Expression  and  Speech. 

3.  Organs  of  Sense,  including  the  Nerves. 

4.  Organs  of  Circulation. 

5.  The  Fascia. 

The  organs  of  digestion  comprise  those  of — 

1.  Prehension,  3.  Insalivation, 

2.  Mastication,  4.  Deglutition, 


ORGANS  OF  PREHENSION.  223 

which,  constitute  the  mouth.  The  mouth  contains  the  den- 
tal organs,  and  has  its  superior  wall  or  roof  formed  by  the 
palatine  processes  of  the  superior  maxillary  and  palate  bones. 
Its  floor  consists  of  the  mylo-hyoid  muscles.  The  lips  bound 
it  in  front,  the  soft  palate  behind,  and  the  cheeks  laterally. 


SECTION    I. 

ORGANS  OF    PREHENSION, 

WHICH    CONSIST    OF    THE    MUSCLES    OF    THE    MOUTH. 

Dissection. — To  expose  the  muscles  of  prehension,  com- 
mence the  first  incision  at  the  meatus  externus  of  the  ear, 
carrying  it  along  the  zygoma  to  the  external  canthus  of 
the  eye;  thence  round  the  lower  margin  of  the  orbit  to  the 
inner  canthus,  and  up  to  the  nasal  spine  of  the  os-frontis; 
from  this  continue  the  incision  along  the  median  line  of 
the  nose  to  its  tip,  thence  down  to  the  margin  of  the  upper 
lip;  from  this  continue  round  the  margin  and  angle  of  the 
mouth  to  the  middle  of  the  lower 

FIG.  55. 

lip;  thence  down  to  the  lower 
margin  of  the  chin;  and  thence 
along  the  sides  and  up  the  rami 
of  the  lower  jaw,  back  to  the 
place  of  beginning.  Make  a  sec- 
ond incision  from  the  promi- 
nence of  the  malar  bone  to  the 
angle  of  the  mouth.  Turn  the' 
integuments  from  the  ear  to- 
wards the  mouth.  Hold  the 
skin  tense,  and  always  dissect 
in  the  course  of,  and  close  to, 
the  fibres  of  the  muscle.  The 

FIG.  55  represents  a  front  view  of  the  Muscles  of  the  Face,  a  a  Anterior 
bellies  of  the  occipito-frontalis.  6  6  Orbicularis  palpebrarum.  c  Fyramidales 
nasi.  d  Compressor  nasi.  e  e  ff  Levator  labii-superioris-alaeque  'nasi.  g  g 
Zygomaticus  minor,  hh  Zygomaticus  major,  ti  Masseter.  jj  Buccinator 
or  trumpeter's  muscle,  k  k  Orbicularis  oris.  1 1  Depressor-labii-inferioris. 
m  Levator  menti.  n  n  Depressor-anguli  oris.  o  o  Levator-anguli-oris. 


224  ORGANS  OE  PREHENSION. 

cavity  of  the  mouth,  should  first  be  filled  with  baked  hair 
or  tow,  (soft  paper  will  answer,)  and  then  sewed  up. 

Levator  Idbii  superioris  alceque  nasi  (Fig.  55)  is  a  trian- 
gular and  thin  muscle,  situated  between  the  orbit  and  upper 
lip,  and  lying  on  the  side  of  the  nose.  It  arises  by  two  heads, 
one  from  the  nasal  process  of  the  superior  maxillary  bone,  the 
other  broad  from  the  orbitary  margin  above  the  infra-orbi- 
tal foramen;  its  fibres  descend  and  are  inserted  into  the 
ala  nasi  and  upper  lip. 

Its  function  is  to  elevate  the  ala  and  upper  lip.  Its 
superior  portion  is  covered  by  the  orbicularis  palpebrarum, 
and  its  orbital  division  is,  by  some,  made  a  distinct  muscle, 
and  called  the  levator  labii  superioris  proprius. 

Depressor  labii  superioris  alceque  nasi  is  a  small  muscle 
situated  on  either  side  of  the  frenum,  and  is  seen  by  raising 
the  upper  lip,  and  lifting  the  mucous  membrane.  It  arises 
from  the  surface  in  front  of  the  alveoli  of  the  incisor  and 
canine  teeth,  and  ascends  to  be  inserted  into  the  upper  lip 
and  ala  of  the  nose.  It  lies  upon  the  bone,  and  is  covered 
by  the  levator  labii  superioris  alwque  nasi  and  the  orbicularis 
vris. 

Its  function  is  to  depress  the  upper  lip  and  ala  nasi,  and 
antagonize  the  levator. 

Levator  anguli  oris  (musculus  caninus)  is  seen  by  raising 
the  levator  labii  superioris  alaaque  nasi  which  covers  it 
It  arises  from  the  canine  fossa  of  the  superior  maxillary 
below  the  infra-orbital  foramen,  having  the  infra-orbitar 
nerves  and  vessels  ramifying  on  its  anterior  surface.  It 
descends  and  is  inserted  into  the  angle  of  the  mouth,  inter- 
mingling its  fibres  with  those  of  the  orbicularis,  depres- 
sor anguli  oris,  and  zygomatic  muscles.  Its  function  is  to 
elevate  the  angle  of  the  mouth. 

Depressor  anguli  oris  (or  triangularis  oris)  is  a  triangu- 
lar, flat  muscle,  having  its  base  below  and  apex  above.  It 
arises  fleshy  and  broad  from  the  external  oblique  ridge  of 
the  lower  jaw,  ascends  converging,  and  is  inserted  into  the 
angle  of  the  mouth,  where  its  fibres  blend  with  the  levator 
anguli,  orbicularis,  and  zygomatic.  Its  function  is  to  de- 


ORGANS   OF  PREHENSION.  225 

press  the  angle  of  the  mouth,  and  antagonize  the  leva- 
tor. 

Levator  Idbii  inferioris  (or  menti)  is  seen  by  turning  down 
the  lower  lip  and  lifting  the  mucous  membrane.  It  arises, 
on  either  side  of  the  frenum,  from  the  surface  in  front  of 
the  alveoli  of  the  incisor  teeth  of  the  lower  jaw;  its  fibres 
descend  and  are  inserted  into  the  integument  of  the  chin. 
Its  function  is  to  elevate  the  chin  and  lower  lip. 

Depressor  labii  inferioris  (quadratics  menti)  is  a  broad 
muscle  intermixed  with  fat,  and  situated  upon  either  side 
of  the  symphysis.  It  arises  from  the  side  and  front  of  the 
inferior  maxilla  at  its  base,  and  is  inserted  into  the  greater 
part  of  the  lower  lip  and  orbicularis  muscle.  Its  function 
is  to  depress  the  lower  lip. 

Zygomaticus  major  is  a  long,  slender  muscle,  and  arises 
from  the  malar  bone  near  the  zygomatic  suture.  It  is  in- 
serted into  the  angle  of  the  mouth.  Its  function  is  to  draw 
the  mouth  upwards  and  backwards,  as  in  smiling. 

Zygomaticus  minor  is  very  small.  It  arises  from  the 
malar  prominence,  and  is  inserted  into  the  upper  lip  near 
the  angle.  This  muscle  is  sometimes  wanting,  and  some- 
times it  is  simply  a  slip  of  the  orbicularis  palpebrarum  by 
which  its  origin  is  covered.  Its  function  is  the  same  as  that 
of  the  zygomaticus  major.  Both  these  muscles  blend  with 
the  others  which  are  inserted  into  the  angle  of  the  mouth. 

Buccinator  (fiovxavov,  a  trumpet,)  is  situated  at  the  side 
of  the  face,  between  the  upper  and  lower  jaws.  It  is  a  thin 
and  broad  sheet  of  muscle,  the  fibres  of  which  run  horizon- 
tally, and  arise  from  the  alveoli  of  the  last  molar  teeth  of 
the  upper  jaw,  as  far  back  as  the  pterygoid  processes;  from 
the  external  oblique  ridge  of  the  lower  jaw,  as  far  back  as 
the  coronoid  process,  and  from  the  pterygo-maxillary  liga- 
ment. It  is  inserted  into  the  angle  of  the  mouth  and  blends 
with  all  the  other  muscles  inserted  here.  Its  function  is  to 
retract  the  lips,  to  diminish  the  cavity  of  the  mouth  by 
drawing  the  cheek  to  the  teeth,  thus  aiding  in  mastication; 
and  to  assist  to  puff  out  the  cheek,  as  in  filling  wind  instru- 
ments. It  is  covered  by  a  quantity  of  fat,  found  in  soft, 
15 


226    BLOOD  VESSELS  SUPPLYING  THE  ORGANS  OF  PREHENSION, 

round  masses,  which  separates  it  from  the  masseter  muscle 
and  ramus  of  the  lower  jaw,  and  by  the  zygomatic,  the 
levator,  and  depressor  anguli-oris  muscles,  together  with 
the  facial  nerves  and  vessels  which  ramify  over  its  surface. 
The  duct  of  Steno  is  seen  passing  through  this  muscle 
at  its  upper  part,  opposite  the  second  molar  tooth  of  the 
upper  jaw. 

Orbicularis-oris  consists  of  two  semi-circular  fleshy  planes, 
surrounding  the  mouth,  intersecting  each  other  at  the  an- 
gles, and  blending  with  all  the  muscles  already  described. 
It  has  one  leading  peculiarity  in  having  no  bony  origin  or 
insertion.  Its  function  is  to  close  the  mouth  and  antagonize 
all  the  muscles  inserted  into  its  angles.  This  muscle  con- 
stitutes the  chief  thickness  of  the  lips,  and  is  intermixed 
with  small  granulated  particles  of  fat. 

COMBINED  ACTION  OF  MUSCLES. 

The  separate  action  of  the  several  muscles  concerned  in 
prehension,  is,  as  we  have  seen,  to  elevate,  depress,  re- 
tract, and  close  the  lips  ;  while  in  their  conjoint  and  har- 
monious action,  they  either  act  separately  or  together,  or 
in  whatever  way  may  best  accomplish  the  great  end  for 
which  they  were  designed.  They  are  also  engaged  in  other 
functions,  as  speaking,  breathing  and  mastication. 

BLOOD  VESSELS  SUPPLYING  THE  ORGANS  OF  PREHENSION. 

1.  Facial  Artery.     2.  Infra  Orbitar.     3.  Transverse  Facial. 

The  Facial  Artery  (Fig.  73)  arises  from  the  external 
carotid,  at  its  front  part,  above  the  lingual,  and  ascends 
to  the  submaxillary  gland  behind,  by  which  it  is  covered. 
It  now  curves  over  the  base  of  the  lower  jaw,  anterior  to 
the  masseter  muscle,  ascends  to  the  commissure  of  the  lips, 
thence  by  the  side  of  the  nose  to  the  angle  of  the  eye, 
where  it  terminates  by  anastomosing  with  the  ophthalmic. 
Its  whole  course  is  very  tortuous,  to  adapt  it  to  the  various 
movements  of  the  jaws. 

Its  branches  are,  the  inferior  palatine,   submaxillary, 


THE  TEETH.  227 

submental,  pterygoid  and  masseteric,  inferior  labial,  infe- 
rior coronary,  superior  coronary,  later alis  nasi,  and  angular. 
Of  these  branches,  the  latter  are  mostly  concerned  in  nour- 
ishing the  organs  of  prehension.  The  inferior  labial  sup- 
plies the  skin  and  muscles  of  the  lower  lip.  The  inferior 
coronary,  leaving  the  facial  at  some  distance  from  the 
angle  of  the  mouth,  proceeds  along  the  border  of  the 
lower  lip,  and  unites  with  its  fellow  of  the  opposite  side. 
The  superior  coronary  pursues  a  similar  course  along  the 
border  of  the  upper  lip,  uniting  with  its  fellow  and  send- 
ing a  branch  to  the  septum  nasi.  The  lateralis  nasi,  and 
the  angular  termination  of  the  facial,  supply  the  ala  and 
dorsum  of  the  nose  and  the  angle  of  the  eye. 

The  Infra-orbital  is  a  branch  of  the  internal  maxillary, 
which,  passing  along  the  infra-orbital  canal,  comes  out  at 
the  infra-orbital  foramen,  supplying  the  muscles  of  the 
upper  lip,  and  anastomosing  witli  the  facial,  transverse 
facial,  alveolar,  buccal  and  ophthalmic  arteries. 

The  Transverse  facial  (trans  vers  alis  faciei)  comes  from 
the  external  carotid  in  the  substance  of  the  parotid  gland ; 
sometimes  it  is  a  branch  of  the  temporal ;  it  runs  parallel 
to  the  duct  of  Steno,  crossing  the  masseter  muscle,  supply- 
ing the  lateral  parts  of  the  mouth,  and  anastomosing  with 
the  facial  and  infra-orbital  arteries. 

The  Veins  correspond  to  the  arteries  and  terminate  in 
the  internal  jugular. 

The  Nerves  of  Prehension  (Figs.  74,  97)  belong  to  the 
5th  and  7th  pair,  which  will  be  described  under  the  heads 
of  organs  of  mastication  and  expression. 

SECTION   II. 

ORGANS  OF  MASTICATION. 

These  organs  are  divided  into  the  passive  and  active. 
The  passive  organs  of  mastication  are 

THE  TEETH. 

The  teeth  constitute  the  immediate  agents  in  mastica- 
tion, are  the  hardest  portions  of  the  body,  and  form  an 


228 


THE  TEETH. 


essential  element  in  the  classification  of  the  animal  king- 
dom. They  occupy  the  alveolar  cavities  of  the  superior 
and  inferior  maxillary  bones,  and  are  fixed  firmly  in  their 
respective  situations  by  a  species  of  articulation  called 
gomphosis  (70^05,  a  nail,)  from  the  supposed  resemblance 
to  the  manner  in  which  a  nail  is  confined  when  driven  into 
a  board,  as  seen  in  Fig.  56. 

The  teeth  in  both 
jaws  are  arranged  in 
what  have  been  called 
the  dental  arches.  The 
size  of  the  arches  in  the 
two  jaws  differs;  that 
of  the  upper  closes  over 
the  incisors  and  canine 
of  the  lower,  and  thus 
forms  the  segment  of 
a  larger  circle — this 
overlapping  in  the  two 
arches  illustrates  their 
adaptation  to  the  cutting  action  ;  and  they  have  been  com- 
pared to  the  blades  of  a  pair  of  scissors.  The  molars,  which 
come  in  contact  by  the  superior  surface  of  their  crowns, 
have  that  position  which  is  best  adapted  for  the  grinding 
and  pounding  motions.  Fig.  75,  from  Nasmyth,  illus- 
trates the  superior  dental  arch  of  man  ;  and  the  same  figure 
shows  the  superior  arch  of  a  chimpanzee.  This  latter  pre- 
sents a  marked  difference  from  the  human  arch,  in  having 
its  lateral  portions  straight,  and  in  presenting  a  space 
between  the  lateral  incisor  and  canine. 
The  teeth  have  two  grand  divisions : 

First,  the  Temporary;  Second,  the  Permanent. 

The  first  division  has  20  teeth;  the  second  32.     Each 
division  is  classified  into, 

1.  Incisors — (incisores.) 

2.  Canines — (cuspidati.) 

3.  Bicuspids — (bi-cuspidati.) 

4.  Molars — (molares.) 


THE  TEETH. 


229 


FIG.  57. 


Description  of  a  Tooth. — Each  tooth  consists  of  a  crown, 
neck,  and  root  or  fang.  The  crown  is  external,  naked,'has 
no  investment  of  periosteum  like  the  bones,  hut  is  covered 
by  a  substance  called  enamel.  The  neck  is  the  contracted 
portion  of  the  tooth,  surrounded  by  the  gum;  while  the 
root,  firmly  fixed  in  the  alveolar  walls,  is  covered  by  the 
periosteum  reflected  from  the  alveoli,  and  has  its  apex 
perforated  for  the  entrance  of  a  nerve  and  artery. 

Description  of  each  class  of  Teeth,  beginning  with  the 
permanent  division.  The  Incisors  (incido,  to  cut,)  are  sit- 
uated in  the  anterior  and  central  alveoli  of  the  upper  and 
lower  jaw.  They  are  four 
in  number  in  each  jaw — 
two  central  and  two  lat- 
eral. The  crown  of  each 
is  wedge-shaped  and 
sharp,  smooth  and  con- 
vex in  front,  concave  be-j 
hind,  and  covered  with  a 
thick  coating  of  enamel. 
The  cutting  edge  is  the, 
widestpart,  and  continues 
narrowing  to  the  extremi- 
ty of  the  fang.  The  root 
has  a  conical  form — is 
single,  and  flattened  on 
its  side,  and  has  an  opening  at  its  apex  for  the  passage  of 
the  vessel  and  nerve  to  the  pulp.  Those  of  the  upper  jaw 
are  larger  and  stronger  than  those  of  the  lower.  The 
central  incisors  of  the  upper  jaw  are  larger  than  the  lat- 
eral; while  in  the  lower,  the  lateral  are  larger  than  the 
central,  though  the  difference  is  slight. 

The  superior  central  incisors  are  the  Iroadest  of  all  t*he 
front  teeth,  measuring  about  four  lines  in  their  crowns. 
The  inferior  central  incisors  are,  on  the  contrary,  the  small- 
est, measuring  only  about  two  lines  and  a  half. 

FIG.  57,  a  a  a  a  Anterior  view  of  the  Incisors  ;  6  6  6  b  Posterior  view ; 
«  c  c  c  Lateral  view. 


230  THE  TEETH. 

The  superior  central  incisors  are  the  longest  of  all  the 
front  teeth  except  the  canine,  being  found  to  have  an  aver- 
age measurement  in  length  of  about  twelve  lines;  while 
the  inferior  central  incisors  are  but  ten  lines  long,  and  are 
the  shortest  of  all  the  teeth.  The  relative  length  of  the 
crown  and  root,  though  subject  to  variation,  is  nearly  equal 
in  the  upper  central  incisors,  while  in  the  inferior  central 
incisors  four  lines  are  assigned  to  the  crown  and  six  to  the 
root.  For  the  lateral  incisors  of  both  jaws,  four  lines  and 
a  half  for  the  crown  and  seven  for  .the  root  are  regarded  as 
the  fair  relative  average  length.  The  anterior  surface  of 
the  central  incisors  is  frequently  marked  by  longitudinal 
ridges,  which  in  early  life  are  found  to  terminate  in  small 
cusps  upon  the  cutting  edge  of  these  teeth — three  of  these 
cusps  are  seen  on  the  central,  and  but  one  on  the  lateral  in- 
cisor. This  serrated  provision  in  the  incisors  is  believed  to 
be  nicely  adapted  to  the  division  of  the  food,  and  designed 
to  compensate  for  the  weak  condition  of  the  dental  system 
and  its  muscular  powers  at  this  early  period.  As  the  per- 
manent teeth  advance  these  cusps  disappear. 

On  the  posterior  surface  of  the  superior  central  incisors, 
which  have  been  stated  to  be  concave,  and  receive  the 
crowns  of  the  lower  incisors  at  an  acute  angle,  raised  un- 
dulations are  described  to  exist  in  early  life,  and  are  re- 
garded as  assisting  in  the  mastication  of  the  food  at  this 
time,  when  the  molars  are  imperfect. 

Professor  Harris  describes  four  surfaces  to  the  crown  of 
an  incisor,  which  he  thus  characterizes:  two  approxirnal, 
one  labial,  and  one  palatine  or  lingual  surface;  also  four 
angles,  a  right  and  left  labio-approximal,  and  right  and 
left  palato-approximal,  or  lingua-approximal. 

Canine,  or  Guspidati — (cuspis,  a  point.)  The  canine  teeth 
are  two  in  each  jaw,  and  situated  one  upon  either  side  of 
the  lateral,  and  with  the  incisors  complete  the  range  of 
•what  are  called  the  oral  teeth.  They  particularly  distin- 
guish the  carniverous  animals,  and  are  designed  to  tear 
and  rend  the  food,  whilst  the  incisors  simply  cut.  The 
crown  is  conical,  and  has  its  anterior  surface  more  con- 


THE  TEETH. 


231 


FIG.  58. 


FIG.  59. 


vex  than  the  incisors,  and  the  posterior 
more  irregular,  and  possessing  a  larger 
tubercle  near  the  neck.  The  roots  are  the 
longest  of  all  the  teeth — larger  than  the 
incisors;  single,  but  marked  by  a  groove, 
showing  an  attempt  towards  the  double 
root 

The   roots  of  the  upper  canines  are 
seen  to  extend  into  the  nasal  process  of 
the  superior  maxilla,  above  the  floor  of 
the  nostrils — and  those  of  the  lower  are 
found  to  descend  about  one  half  of  the 
depth  of  the  lower  jaw,  and  to  be  mid- 
way between  the  anterior  mental  fora- 
men and  the  symphy-sis  menti.   The  supe- 
rior edge  of  the  upper  canine  is  greater 
than  that  of  the  lower,  the  former  being 
estimated  at  about  four 
lines,  the  latter  about 
three  and  a  half.     The 
upper  canine  is  larger 
than  the  lower,  mea- 
suring about  thirteen 
lines — to  the  crown  is 
given  six  lines  for  its 
length,  and  to  the  root 
seven  lines.  The  root  is 
not  unfrequently  found 
curved  or  undulating. 

The  canine  presents 
on   the   middle  of  its 
anterior  surface  a  ridge 
which  ends  on  the  summit  in  a  cusp.     On  either  side  of 
this  middle  ridge,  two  other  ridges  are  seen  but  not  ter- 

FIG.  58,  a  a  View  of  the  Cuspids,  or  canine,  from  before;  b  b  View  of 
the  same  from  behind  ;  c  c  Side  view. 

FIG.  59,  aaaa  View  of  the  Bi-cuspids  from  without;  b  b  b  b  View  from 
within ;  c  c  c  c  Side  view. 


232  THE  TEETH. 

minating  in  cusps.  On  the  posterior  surface  "undulating 
ridges,"  running  transversely,  are  seen,  but  more  distinct 
in  the  upper  than  in  the  lower  canines.  The  summits  of 
the  canines  are  tubercular  and  oblique,  and  their  cusps 
disappear  in  the  adult. 

Ei-Cusplds  (Bi-Cuspidati — Fig.  59.) — The  bi-cuspids  are 
upon  either  side  of  the  canines,  and  are  four  in  each  jaw ; 
they  are  intermediate  in  size  between  the  canines  and  mo- 
lars, and  derive  their  name  from  having  two  tubercles  on 
their  grinding  surfaces.  A  groove  running  in  the  direction 
of  the  alveolar  arch  separates  these  tubercles;  the  outer  is 
larger  than  the  inner,  and  those  of  the  upper  larger  than 
those  of  the  lower  jaw.  The  body  is  thicker,  and  the  sides 
are  flatter,  than  either  the  incisors  or  cuspidati.  Their 
roots  are  single,  though  the  groove  is  much  deeper  than 
the  canine,  and  often  divides  it  into  two. 

The  necks  of  the  bi-cuspids  are  smaller,  in  proportion  to 
their  crowns,  than  those  of  any  other  teeth ;  hence  the 
necessity  of  using  more  caution  in  their  extraction,  as  they 
are  more  liable  to  fracture. 

Professor  Harris  gives  a  bi-cuspis  five  surfaces,  two  ap- 
proximalj  one  buccal,  one  palatine  or  lingual,  and  a  grinding 
surface;  also  four  angles,  one  anterior,  and  one  posterior 
palato-approximal,  and  one  anterior,  and  one  posterior 
bucco-approximal. 

MolareSj  or  Multi-Cuspidati. — The  posterior  teeth  in  the 
alveolar  arch  of  each  jaw  constitute  the  true  molars  or 
grinders,  and  with  the  bicuspids  form  what  is  called  the 
buccal  range.  There  are  six  to  each  jaw,  three  upon  either 
side  behind  the  bicuspids.  Their  greater  size  distinguishes 
them.  The  crown  of  each  presents  a  square  form,  and 
has  on  the  grinding  surface  four  and  five  tubercles,  with 
as  many  depressions,  which  are  so  arranged  that  the  tuber- 
cles of  either  jaw  are  adapted  to  corresponding  depressions 
in  the  other. 

There  are  three  roots,  and  sometimes  four,  to  the  upper 
molars;  two  of  these  roots  are  external,  nearly  parallel  and 
vertical.  The  third  is  internal,  directed  to  the  roof  of  the 


THE  TEETH. 


233 


mouth,  and  forms  an  acute  angle  with  the  other.  The  mo- 
lars of  the  lower  jaw  have  but  two  roots,  the  one  anterior, 
the  other  posterior;  they  are  flattened  very  much  laterally, 
grooved,  and  sometimes  bifid.  The  first  molar  is  the  largest, 
the  third  or  last,  called  dens  sapientice}  is  the  smallest  and 
shortest.  The  wisdom  tooth  of  the  upper  jaw  has  its  roots 
sometimes  united  into  one,  while  the  root  of  the  lower  is 

FIG.  60. 


conical  and  generally  single. 
The  roots  of  the  first  two  I 
upper  molars  are  situated  be- 
neath the  floor  of  the  antrum, 
and  occasionally  perforate 
this  cavity.  Those  of  the  last 
inferior  molars  are  found  in 
the  base  of  the  coronoid  pro- 
cesses. The  apex  of  all  the  roots 
are  perforated  for  the  trans- 
mission of  vessels  and  nerves. 
The  roots  of  the  molar  teeth 
in  both  jaws  are  found  not 
unfrequently  to  approach  each  other,  and  thus  enclose  the 
osseous  wall  which  divides  them.  From  this  arrangement 
they  offer  considerable  difficulty  to  extraction.  The  inter- 

FIG.  60,   a  a  a  a  a  a  Exterior  view  of  the  molars,     b  b  I  b  I  b  Interior 
view,     c  c  c  c  c  c  Lateral  view. 


234  THE  TEETH. 

nal  root  of  the  upper  molar  is  seen  sometimes  to  be  joined 
by  a  " broad  plate"  to  the  anterior  external,  and  then 
again  all  three  have  been  found  united  in  one  mass.  The 
roots  of  the  lower  molars  are  seen  occasionally  to  be  sim- 
ilarly connected.  And,  indeed,  so  great  is  this  irregularity 
in  the  roots  of  the  molars,  as  to  length,  figure  and  direc- 
tion, that,  according  to  Mr.  Nasmyth,  it  is  impossible  to 
tell  beforehand  the  amount  of  resistance  to  be  encountered 
in  their  removal.  The  average  length  of  a  molar  he  esti- 
mates at  from  eight  to  thirteen  lines. 

In  reference  to  the  function  of  the  molars,  this  same 
gentleman  uses  the  following  language:  "The  mechanical 
disposition  of  the  molar  teeth  is  beautifully  fitted  to  the 
purposes  which  these  organs  have  to  fulfil;  for  example, 
the  first  act  of  mastication,  consisting  in  the  closure  of  the 
lower  against  the  upper  jaw,  while  it  secures  the  food, 
makes  its  greatest  force  of  pressure  against  the  outer  limb 
of  the  crown  of  the  superior  molars,  that  limb  which  we 
know  to  be  supported  by  two  out  of  the  three  roots  of  the 
tooth. 

"Again,  when  trituration  ensues,  the  ramus  of  the  jaw  is 
drawn  inwards,  and  the  chief  amount  of  pressure  is  trans- 
ferred to  the  outer  limb  of  the  lower  molars,  where  the 
greatest  strength  of  fang  exists." 

Structure. — The  structure  of  each  tooth  consists  essential- 
ly of  three  parts,  the  pulp,  dentine  or  ivory,  and  enamel,  to 
which  the  cementum  or  crusta-petrosa  is  added,  (Fig.  61,  A.) 
Each  tooth  contains  within  itself  a  cavity  for  lodging  the 
pulp,  called  the  pulp  cavity,  (Fig.  61,  B,  C.)  The  shape  of  the 
cavity  corresponds  to  that  of  the  tooth  to  which  it  belongs. 
The  dental  pulp  has  the  same  form  as  the  cavity,  and  is  de- 
scribed by  Mr.  Thos.  Bell,  as  "  very  soft,  gelatinous,  and 
semi-transparent,  and  having  its  surface  covered  by  an  ex- 
tremely delicate,  thin,  vascular  membrane,  closely  attached 
to  it  by  vessels." 

The  vessels  (Fig.  62,  from  a  drawing  by  Mr.  Nasmyth) 
which  supply  the  pulp,  enter  the  tooth  at  the  apex  of  its 
root,  forming  a  capillary  net-work  on  the  pulp,  and  show 


THE  TEETII. 


235 


FIG.  61. 


the  great  vascular- 
ity  of  this  tissue; 
the  larger  vessels 
are  deep,  and  run 
tortuously  in  the 
longitudinal  direc- 
tion; the  arteries 
and  veins  commu- 
nicate by  an  im- 
mense number  of 
looped  capillaries, 
as  seen  in  the 
drawing. 

The  nerves  of  the  pulp  (Fig.  63,  taken  also  from  Mr. 
Nasmyth)  come  from  the  superior  and  inferior  maxillary 
divisions  of  the  fifth,  accompany  the  artery,  and  are  seen  to 
form  a  series  of  loops.  The  pulp  thus  seems  to  be  consti- 
tuted of  blood  vessels  and  nerves,  surrounded  by  a  very 
delicate  membrane. 

FIG.  61,  A  represents  the  different  structures  composing  a  tooth,  a  Pulp. 
6  Dentine,  c  Enamel,  d  Crusta-petrosa,  or  cementum. 

FIG.  61,  B  represents  the  pulp  cavities  of  the  permanent  teeth  from  vertical 
sections. 

FIG.  61,  C  represents  thepuJp  cavities  of  the  permanent  teeth  of  both  jaws, 
from  transverse  sections  at  their  necks. 


236 


MICROSCOPIC  ANATOMY  OF  THE  PULP. 


MICROSCOPIC  ANATOMY  OF  THE  PULP. 
FIG.  62.  FlG  63. 


According  to  the  mi- 
croscopic observations  of 
Mr.  Nasmyth,  the  pulp 
consists  of  a  structure 
essentially  cellular,  (as 
exhibited  in  Fig.  64,  A.) 
which  he  calls  the  ret- 
icular  tissue.  These  cells 
constitute  the  "principal 

FIG.  62  represents  the  vascularity  of  the  pulps  of  one  of  the  central  incisor 
teeth  of  the  upper  jaw.  The  deeper  vessels  are  seen  to  be  large,  and  the 
looped  communication  between  the  capillary  arteries  and  veins  is  distinctly 
shown.  The  small  figure  shows  the  pulp  of  natural  size. 

FIG.  63  represents  the  pulp  of  an  adult  bi-cuspid,  and  the  arrangment  of 
its  nerves— magnified  twenty  times. 


MICROSCOPIC  ANATOMY  OF  THE  PULP. 


23T 


portion"  of  the  bulk  of  the  tooth.  They  vary  very  much 
in  size  and  shape,  being  estimated  from  the  ten-thousandth 
to  the  one-eighth  part  of  an  inch  in  diameter.  They  are 
disposed  throughout  the  pulp  in  concentric  layers,  and 
have  granules  interspersed  among  them. 


The  microscope  of  this  gentleman  also  shows  the  pulp 
cells  to  consist  of  a  membrane,  cavity  and  nucleus.  The 
nucleus  generally  occupies  the  lateral  portion  of  the  cell- 
wall,  though  some- 
times found  in  the 
centre  of  its  cavity. 
The  nuclei  of  all 
the  cells  are  compo- 
sed of  animal  tissue, 
and  remain  as  such 
without  any  trans- 
formation ;  while  the 
cells  themselves  un- 
dergo a  "conversion"  into  ivory,  by  the  deposition  in  their 
interior  of  calcareous  salts.  The  nuclei,  arranged  in  a 
"linear  succession,"  constitute  "the  fibres  of  the  ivory," 

FIG.  64,  A,  the  Cellular  arrangement  in  a  portion  of  the  body  of  the  pulp. 

FIG.  64,  B  represents  the  presence  of  Vesicles  on  the  superficial  layer  of  the 
pulp — not  an  unfrequent  occurrence  according  to  Mr.  Nasmyth. 

FIG.  64,  C,  another  variety  in  the  arrangement  of  the  Cells  of  the  pulp. 

FIG.  65,  A  represents  the  baccated  or  beaded  appearance  of  Dentine,  accord- 
ing to  Mr.  Nasmyth. 

FIG.  65,  B  represents  a  portion  of  the  Pulp,  as  well  as  the  ivory,  and  shows 
the  fibres  to  be  continuous  with  the  parietes  of  the  cells. 


238  DENTINE  OR  IVORY. 

and  are  imbedded  in  the  osseous  substance.  These  fibres 
are  solid,  instead  of  tubular  as  supposed  by  Ketzius  and 
others, — and  they  present  (from  the  peculiar  arrangement 
of  their  nuclei)  a  beaded  or  "baccated"  appearance — as 
seen  in  Fig.  65,  A. 

The  fibres  of  the  pulp  are  observed  to  be  spiral  in  their 
course,  but  less  so,  and  rather  undulating  where  the  ivory 
is  deposited  around  them.  The  pulp  is  enclosed  in  a 
double  sac — the  outer  one  stated  by  Mr.  Hunter  to  be 
"soft,  spongy,  and  without  vessels,"  while  the  inner  is 
very'  vascular  and  firm.  Mr.  Blake  on  the  other  hand 
makes  the  outer  to  be  full  of  vessels,  as  well  as  spongy,  and 
the  inner  to  be  destitute  and  delicate.  The  injections  of 
Mr.  Fox,  preparations  of  Mr.  Bell,  and  observations  of  Pro- 
fessor Harris,  all  seem  to  show  that  both  membranes  are 
decidedly  vascular.  At  an  early  period  when  this  sac, 
termed  the  dental  capsule,  is  about  to  close  its  follicular 
stage,  from  being  a  mucous  membrane,  presents,  according 
to  Mr.  Nasmyth,  a  "white,  silvery,  loose,  and  rugous" 
appearance,  which,  under  the  microscope,  exhibits  minute 
cells  differing  from  those  of  the  epithelium,  while  the  inter- 
nal layer  of  the  sac,  according  to  this  same  authority,  pre- 
sents layers  of  loose  cells,  of  oval  shape,  containing  nuclei 
and  some  granular  matter,  but  destitute  of  vessels.  This 
layer,  however,  he  states,  has  beneath  it  a  net-work  of 
vessels,  "supported  by  a  web  of  areolo-fibrous  tissue/' 
which  readily  accounts  for  both  layers  of  the  capsule  being 
considered  vascular. 

The  dental  capsule  is  found  to  be  connected  with  the 
alveolar  periosteum,  and  so  blended  with  it,  as  to  be  con- 
sidered a  single  membrane.  Mr.  Bell  makes  one  of  its 
attachments  inseparable  from  the  gums,  and  the  other  con- 
nected with  the  pulp,  where  the  vessels  and  nerves  enter. 

DENTINE  OR  IVORY. 

Dentine  or  Ivory,  (see  Fig.  61,  A,)  forms  by  far  the 
most  abundant  constituent  of  a  tooth,  composing  the 
whole  of  the  body,  root  and  neck,  excepting  the  thin  cov- 


DENTINE  OR  IVORY.  239 

ering  of  enamel,  the  crusta  petrosa,  and  pulp.  Its  color 
is  a  yellowish  white,  and  presents  when  broken  a  fibrous 
appearance.  It  is  harder  than  bone.  Chemical  analysis 
makes  ivory  to  consist,  in  100  parts,  of 

Phosphate  of  lime,  61.95 

Fluate  of  lime,  2.10 

Carbonate  of  lime,  5.30 

Phosphate  of  magnesia,  1.25 

Soda  and  chloride  of  sodium,  1.40 

Cartilage  and  water,  28.00 

According  to  Mr.  Nasmyth,  ivory  presents  three  varieties. 
The  first,  consisting  of  a  "  regular  series  of  fibres  and  cells," 
called  Jibro-cellular,  and  regarded  as  the  most  perfect  kind 
of  ivory,  forms  the  greater  portion  of  the  teeth  of  man,  and 
is  found  to  strongly  characterize  both  classes  of  the  mam- 
malia and  reptilia.  The  second  variety  of  ivory  presents 
vertical  canals  traversing  it,  as  seen  particularly  in  the 
teeth  of  fish,  and  is  called  canalicular.  The  third  variety, 
from  exhibiting,  like  bone,  little  corpuscular  bodies  scat- 
tered through  its  substance,  receives  the  name  of  corpus- 
cular ivory.  Specimens  of  this  latter  are  noticed  in  the 
teeth  of  the  walrus,  sloth,  &c.,  and  is  stated  to  exist  in  the 
human  tooth,  sometimes,  when  diseased. 

The  structure  of  the  dentine,  and  its  relation  to  the  pulp, 
are  seen  in  Fig.  61,  A,  after  Ketzius;  here  the  fibres  are  rep- 
resented as  tubular,  the  tubes  or  dental  canals  opening  by 
circular  orifices  in  the  pulp  cavity,  from  which  they  traverse 
the  body  of  the  tooth,  in  a  curvilinear  direction,  to  end  in 
cul  de  sacs  at  the  outer  margin  of  the  dentine,  or  at  the 
enamel.  These  tubes  are  represented  as  having  distinct 
parietes,  branching  in  their  course,  some  bifurcating  at 
their  termination,  others  at  their  middle,  and  containing  a 
serous  fluid,  which  is  supposed  to  be  intended  for  the  nour- 
ishment of  the  tooth,  by  imbibition.  It  appears  from  Mr. 
Nasmyth's  later  experiments  that  the  structure  of  dentine 
is,  like  that  of  the  pulp,  essentially  cellular  and.  fibrous — that 
is,  consisting  of  cells  and  fibres — and  that  these  cells  assume 


240  BLOOD-VESSELS  OF  IVORY  OR  DENTINE. 

different  shapes  in  different  ani- 

FIG.  66.  .111 

mals,  so  much  so,  indeed,  as  to  be 
regarded  an  important  feature 
in  the  classification  of  the  animal 
kingdom.  But  notwithstanding 
the  difference  in  shape,  in  the 
\  ivory  cells  of  different  animals, 
they  all  nevertheless  have  one 
character  in  common,  i.  e.  their 
baccated  (or  headed)  appearance 
as  seen  in  Fig.  65,  A.  The  beads 
represent  the  nuclei  of  the  differ- 
ent cells,  which,  as  before  stated, 
consist  of  animal  tissue,  remain 
as  such,  and,  connected  in  a  lin- 
ear series,  constitute  the  fibres 
of  the  ivory, — while  around  the 
fibres,  and  within  the  cells,  is 
deposited  the  calcareous  matter, 
giving  hardness,  density,  and 
strength  to  the  ivory.  The  fibres 
themselves  are  also  found  to  be 
solid,  instead  of  tubular  as  Ket- 
zius  thought,  and  the  interfi- 

brous  substance,  instead  of  being  structureless,  to  consist 

of  organized  cells. 

BLOOD-VESSELS  OF    DENTINE  OR    IVORY. 

The  vascularity  of  dentine  is  generally  denied  by  anat- 
omists; but  Fig.  66,  taken  from  an  injected  specimen  in 
the  possession  of  Professor  Harris_,  seems  clearly  to  show 
it  has  a  circulation,  and  in  his  Principles  and  Practice  of 
Dental  Surgery,  he  states  that  similar  specimens  are  in  the 
possession  of  Dr.  Maynard.  In  vol.  2  of  the  American 
Journal  of  Dental  Science,  the  doctor  uses  the  following 
language  in  explanation  of  the  above  figure,  "the  second 
time  he  had  the  good  fortune  to  make  this  discovery,  it 
was  in  the  half  of  an  inferior  molaris,  taken  from  the 


FORMATION   OF  DENTINE.  241 

mouth  of  a  boy  eleven  years  of  age,  and  of  which  an  exact 
representation  of  a  microscopic  view  of  it  is  annexed.  (Fig. 
66.)  The  tooth  had  ached  violently  for  several  days  pre- 
vious to  its  extraction,  from  which  circumstance  he  was 
induced  to  believe  that  the  vessels  of  the  pulp  were  highly 
injected,  and  to  satisfy  himself  upon  the  subject,  he  soon 
after  its  removal  split  it  open  with  a  strong  pair  of  ex- 
cising forceps.  As  was  anticipated,  the  vessels  of  the  pulp 
were  filled  with  red  blood,  and  on  examining  the  half  of 
the  tooth  in  which  this  had  remained,  through  a  micro- 
scope, a  number  of  vessels  within  the  very  substance  of  the 
bone,  charged  with  this  fluid,  were  distinctly  seen."  The 
crown  is  represented  as  decayed. 

Formation  of  the  Dentine. — The  ossification  of  a  tooth,  it 
is  well  known,  commences  on  the  surface  of  the  pulp,  and 
according  to  the  experiments  of  Mr.  Hunter,  from  feeding 
animals  on  madder,  this  ossific  matter  is  laid  layer  within 
layer,  from  the  surface  to  the  centre,  till  the  tooth  is  com- 
pleted, the  pulp  retiring  and  diminishing  as  ossification 
advances. 

The  incisors  begin  to  ossify  by  three  points,  the  cuspids 
by  one,  the  bicuspids  by  two,  and  the  molars  by  three, 
four,  or  five,  according  to  the  number  of  projections  or 
tubercles  upon  their  grinding  surface.  The  crown  of  the 
tooth  being  formed,  the  roots  are  next  observed  to  be  de- 
veloped, and  their  number  always  previously  indicated  by 
the  number  of  distinct  vessels  and  nerves  going  to  the 
pulp. 

This  view  of  the  formation  of  dentine  has  been  termed 
the  excretion  theory.  The  later  researches  of  Mr.  Nasmyth 
give  another  view  of  the  subject ;  observing  the  similarity 
of  structure  between  the  pulp  and  dentine,  that  each  pos- 
sessed the  cellular  or  reticular  arrangement,  (in  his  own 
comprehensive  language)  he  remarks,  u  My  theory,  indeed, 
is  most  simple,  the  cells  of  the  pulp  are  converted  into 
ivory  cells  by  the  deposition  within  them  of  earthy  salts, 
and  the  cells  so  converted,  with  their  nuclei,  are  the  perfect 
ivory ;  moreover,  the  nuclei  assume  a  peculiar  arrange- 
16 


242 


THE  ENAMEL. 


ment  and  constitute  the  structure  which  I  have  described 
and  demonstrated  by  the  name  of  baccated  fibre."  See 
Fig.  65,  A. 

FIG.  67. 

ABC 


Mr.  Tomes  makes  three  stages  in  the  formation  of  den- 
tine or  ivory.  1st.  The  Areolar,  consisting  of  a  very  fine 
tissue,  which  he  calls  the  preparatory  stage.  2d.  Cellular, 
(Fig.  6I7,  A,)  in  which  the  cells  are  scattered  irregularly  and 
have  no  definite  arrangement.  3d.  The  Linear,  where  the 
cells  (Fig.  67,  B)  are  disposed  in  regular  rows,  vertical  to  the 
coronal  surface.  From  this  third  stage,  Mr.  Tomes  thinks, 
the  regular,  continuous,  permanent  tubes  of  dentine  re- 
sult— these  vertical  cells  becoming  united,  end  to  end, 
opening  into  each  other  and  forming  a  communication :  so 
that  if  the  baccated  appearance  of  Mr.  Nasmyth  is  seen,  it 
is  regarded  as  an  arrest  of  development,  and  exhibiting 
dentine  in  an  imperfect  state. 

The  Enamel  (Fig.  61,  A)  covers  the  crown  of  the  tooth ;  is 
thickest  upon  the  cutting  and  grinding  surfaces,  and  is 
much  the  hardest  portion.  Its  hardness  is  so  great  as  to 
strike  fire  with  steel,  and  resist  the  file  or  saw ;  hence  it  is 
well  suited  to  oppose  the  pressure  and  friction  to  which  it 
is  constantly  liable.  Its  color  is  a  pearly  white,  and  it  is 
very  brittle.  It  is  found  to  consist  of  fibres,  or  minute 

FIG.  67,  A  represents  the  Dentine  in  its  second  stage. 
FIG.  67,  B  represents  the  Dentine  in  the  early  part  of  the  third  stage. 
FIG.  67,  C  represents  the  Dentine  at  the  completion  of  the  third  and  most 
perfect  stage. 


CRUSTA-PETROSA   OR  CEMENTUM. 


243 


hexagonal  prisms,  arranged  perpendicularly  to  the  surface 
of  the  ivory  parallel  to  each  other,  and  having  one  of  their 
extremities  resting  upon  the  ivory,  and  the  other  forming 
the  free  surface  of  the  crown,  as  seen  in  Fig.  68,  A.  A  thin 
membrane  is  described  as  separating  the  enamel  from  the 
ivory,  and  is  found,  by  Mr.  Nasmyth,  to  be  composed 
of  cells.  The  enamel,  like  ivory,  consists  also  of  animal 
and  earthy  matter,  and  is  chemically  composed,  according 
to  Berzelius,  in  100  parts;<of 

Phosphate  of  lime,  85.3       Phosphate  of  magnesia,      1.5 
Fluoride  of  calcium,  3.2        Soda  and  muriate  of  soda,  1. 
Carbonate  of  lime,      8.         Animal  matter  and  water,  1. 
A  FIG.  68.  C 


Orusta-petrosa  (or  cementum) 
(Fig.  61,  A)  forms  a  thin  coating 
of  osseous  lamina  to  the  root 
of  the  tooth,  from  the  neck 
where  the  enamel  ends,  to  the 
apex  of  the  fang.  In  some  animals — as  the  elephant — it 
is  continued  over  the  enamel  as  a  thick  layer.  In  struc- 
ture, it  has  the  calcegerous  cells  and  tubuli,  and  consists 
of  true  bone.  Its  quantity  increases  as  age  advances,  and 
presents,  sometimes  in  old  people,  an  exostosis  on  the 

FIG.  68,  A  represents  the  hexagonal  termination  of •  the  Enamel  fibres. 
1,  2,  3,  show  the  irregular  crevices  between  the  hexagonal  fibres. 

FIG.  68,  B  represents  a  lateral  view  of  the  Enamel  fibres.  1  1  Enamel 
fibres  ;  2  2  Transverse  stripes. 

FIG.  68,  C  represents  a  view  of  the  Enamel  on  a  vertical  section. 


244 


BLOOD-VESSELS  OF  DENTINE   OR  IVORY. 


roots,  and  even,  it  is  said,  extends  into  and  fills  up  the 
pulp  cavity  of  the  tooth. 

A  FIG.  69.  B 


Eruption  of  the  Temporary  Teeth. — The  precise  time  when 
the  temporary  teeth  make  their  appearance,  is  not  always 
the  same,  though  the  general  law  of  fixed  limitation,  and 
of  a  regular  time  of  appearing,  if  not  interrupted  by  any 
disturbing  cause,  is  as  true  and  certain  as  with  any  other 
portion  of  the  body. 

Mr.  Thomas  Bell's  observations  make  the  four  central 
incisors  to  appear  at  from  five  to  eight  months  after  birth ; 
the  four  lateral,  from  seven  to  ten ;  the  four  anterior  mo- 
lars, twelve  to  sixteen ;  the  cuspidati,  from  fourteen  to 

% 

FIG.  69,  A  represents  an  anterior  view  of  the  Temporary  Teeth. 

FIG.  69,  B  represents  a  posterior  and  inner  view  of  the  same. 

FIG.  69,  C  represents  a  side  view  of  the  temporary  teeth. 

FIG.  69,  D  represents  a  vertical  section,  so  as  to  exhibit  their  pulp  cavities. 


BLOOD-VESSELS  OF  DENTINE  OR  IVORY.  245 

twenty;  and  the  four  posterior  molars  is  from  eighteen 
to  thirty-six  months. 

Professor  Harris,  who  has  devoted  much  attention  to 
this  point,  thinks  Mr.  Bell  in  error,  in  regard  to  the  ap- 
pearance of  the  posterior  molars.  His  observations  fix 
the  period  from  twenty-four  (instead  of  eighteen)  to  thirty- 
six  ;  though  he  admits  exceptions  to  the  general  rule. 

The  teeth  have  sometimes  made  their  appearance  at 
birth,  showing  extreme  forwardness  in  their  eruption ;  and 
on  the  other  hand,  cases  are  stated,  where  the  eruption  did 
not  occur  till  ten  years  after  birth. 

Eruption  of  the  Permanent  Teeth. — The  accompanying 
figure  (70)  shows  the  relative  position  of  the  two  sets  of 
teeth.  The  permanent,  it  will  FIG  7Q 

be  seen,  are  behind  the  tempo- 
rary set;  and  the  period  of  their 
eruption  is  regarded  much  more 
variable  than  the  temporary. 
The  following  order  in  the 
time  of  their  eruption,  is  given 
by  Professor  Harris:  "First 
molars,  from  fifth  to  sixth  year; 
central  incisors,  from  sixth  to 
eighth ;  lateral  incisors,  from 
seventh  to  ninth ;  first  bicuspids,  ninth  to  tenth ;  second 
bicuspids,  tenth  to  eleventh  and  a  half;  cuspidati,  eleventh 
to  twelfth;  second  molars,  twelfth  to  fourteenth;  and  the 
third  molars  (dentes  sapientise),  from  eighteenth  to  twen- 
tieth." 

The  power,  agency,  and  manner  in  which  the  teeth  are 
made  to  rise  out  of  their  prison-houses,  the  alveolar  cells, 
and  come  through  the  gums,  are  not  settled.  Some  sup- 
pose the  process  entirely  mechanical,  and  that  the  tempo- 
rary set  are  pushed  out  of  their  places  by  the  advance  of 

FIG.  70  represents  the  two  sets  of  teeth  in  a  child  four  years  old.  The  ex- 
terior walls  of  each  jaw  have  been  removed  to  show  the  relative  position  of 
each  set. 

The  illustrations  of  the  temporary,  together  with  those  of  the  permanent 
teeth,  and  several  others,  were  kindly  furnished  the  author  by  Professor 
Harris. 


246  TEMPORARY  AND  PERMANENT  TEETH. 

the  permanent,  though  we  are  not  informed  what  pushes 
forward  these  last. 

Others  again  attribute  it  to  the  prolongation  of  the 
pulp,  &c.,  while  Delabarre  and  Harris  think  a  much  more 
philosophical  explanation  is  to  be  found  in  the  sac  of  the 
tooth  itself,  which,  they  think,  possesses  the  power  of  con- 
traction ;  and  as  the  uterus  expels  the  child,  so  it  extrudes 
the  tooth.  This  is  a  very  ingenious  and  satisfactory  theory, 
provided  this  contractile  power  and  its  efficiency  can  be 
established. 

An  equally  great  diversity  of  opinion  is  entertained  in 
reference  to  the  shedding  of  the  teeth. 

Absorption  of  the  partitions  between  the  two  sets  of 
teeth,  and  subsequently  of  the  roots  of  the  temporary,  from 
the  pressure  of  the  advancing  permanent  teeth,  is  regarded 
by  Mr.  Fox  as  the  prime  agent.  Others  think  the  process 
entirely  mechanical,  a  sort  of  abrasion  by  the  rising  tooth. 
Others  again  believe  that  the  vessels  cease  to  carry  fluids,  and 
that  the  teeth  consequently  die,  and  drop  out  for  the  want 
of  the  necessary  nutrition ;  while  others  give  the  operation 
a  chemical  solution :  among  the  latter  are  Delabarre  and 
Harris.  A  "fungiform  or  carneous  substance"  is  spoken  of 
as  existing  behind  the  roots  of  the  temporary  teeth,  called 
"absorbing  apparel,"  whose  office  it  is  to  exhale  a  chemical 
fluid  which  has  the  power  of  dissolving  the  roots,  and  thus 
removing  them.* 

DIFFERENCE  BETWEEN  THE  TEMPORARY  AND   PERMANENT  TEETH. 

We  will  quote  the  language  of  Mr.  Bell  on  this  head. 
"  The  temporary  teeth  are,  generally  speaking,  much 
smaller  than  the  permanent — of  a  less  firm  and  solid  tex- 
ture, and  their  characteristic  forms  and  prominences  much 
less  strongly  marked.  The  incisors  and  cuspidati  of  the 
lower  jaw  are  of  the  same  general  form  as  in  the  adult, 
though  much  smaller ;  the  edges  are  more  rounded,  and 
they  are  not  much  more  than  half  the  length  of  the  latter. 

*  For  further  information  on  this  point,  see  flarris's  Principles  and  Practice 
of  Dental  Surgery. 


IRREGULARITIES  OF  THE  TEETH.  24*7 

The  molares  of  the  child,  on  the  contrary,  are  considerably 
larger  than  the  bicuspids  which  succeed  them,  and  resem- 
ble, very  nearly,  the  permanent  molares. 

"  The  roots  of  these  teeth — the  molares  of  the  child — are 
similar  in  number  to  those  of  the  adult  molares,  but  they 
are  flatter  and  thinner  in  proportion — more  hollowed  on 
their  inner  surfaces,  and  diverge  from  the  neck  at  a  more 
abrupt  angle,  forming  a  sort  of  arch." 

DIFFERENCES  BETWEEN  THE  TEETH  AND  BONE. 

Six  points  of  difference  exist  between  teeth  and  bone. 

1.  Every  tooth  has  its  larger  portion  naked  and  exposed 
to  the  air ;  while  bone,  on  the  contrary,  is  surrounded  at 
every  point  by  periosteum  or  cartilage, 

2.  The  structure  of  a  tooth  is  more  compact,  has  not  so 
much  of  the  animal,  but  more  of  the  mineral  ingredient 
than  bone.  Is  also  less  vascular  and  not  so  highly  organized. 

3.  The  cavity  of  a  tooth  contains  a  pulp,  instead  of  the 
medulla  of  bone, 

4.  The  diseases  of  teeth  and  their  power  of  recovery 
differ  from  bone. 

5.  Their   development   and  growth    differ   from   bone. 
Teeth  develop  themselves  from  the  surface  to  the  centre ; 
bone,  on  the  contrary,  from  the  centre  to  the  circumference. 
Teeth  commence  by  a  mucous  papilla  or  bulb,  enclosed  in 
a  sac,  which  is  at  first  the ,  depressed  mucous  membrane, 
forming  a  follicle ;  and  have  three  stages  of  growth,  the  pa- 
pillary, follicular,  and  saccular,  while  the  three  stages  of 
bone  are  the  mucous,  cartilaginous,  and  osseous. 

6.  The  duration  of  teeth  is  less  than  that  of  bone,  and 
once  during  life  they  are  completely  renewed,  entirely  dis- 
placed by  a  new  and  wholly  different  set,  a  thing  unknown 
to  bone. 

IRREGULARITIES  OF  THE  TEETH. 

Any  deviation  from  the  natural  condition  of  the  teeth, 
whether  in  the  time  of  their  appearance,  their  number,  posi- 
tion, form,  size,  or  intimate  structure,  may  in  the  most  com- 
prehensive sense  of  the  term,  be  considered  an  irregularity, 


248  ORIGIN   AND   DEVELOPMENT   OF   THE  TEETH. 

though  the  term  is  most  usually  restricted  to  misplacement 
in  position  and  number. 

The  permanent  teeth  most  frequently  deviate  from  their 
natural  places  and  exhibit  irt^egularity  in  their  arrange- 
ment. The  incisors  and  cuspidati,  it  is  said,  present  an 
improper  direction  oftener  than  any  of  the  other  teeth.  Some 
teeth  may  be  said  to  vary  in  improper  direction  when  they 
are  out  of  the  line  of  the  proper  arch,  and  project  either  too 
far  forwards  or  too  far  backwards ;  or  when,  with  this  de- 
viation, there  is  an  additional  irregularity,  by  which  they 
are  turned  about  and  have  their  anterior  and  posterior  sur- 
faces presenting  very  obliquely  forwards  and  backwards. 
Another  irregularity  in  position  is,  where  the  teeth  change 
places ;  thus  the  central  incisor  has  been  seen  to  take  the 
place  of  the  lateral,  and  the  lateral  of  the  central.  .  Again, 
irregularity  of  teeth  may  occur  not  only  in  consequence  of 
change  of  position,  but  different  parts  of  the  tooth  itself- 
may  change,  as  in  the  upper  jaw,  for  example,  the  crown 
may  be  above  and  the  roots  below,  looking  towards  the  al- 
veolar surface — an  instance  of  which  is  seen  in  the  Museum 
of  the  Baltimore  College  of  Dental  Surgery. 

The  irregularity  in  number  may  be  either  a  deficiency  or 
excess.  Instances  are  cited  in  which  the  teeth  have  all  been 
wanting,  or  a  great  number  have  been  absent ;  or,  as  we 
are  told,  they  have  been  fused  together  so  as  to  constitute 
but  a  single  piece.  Those  which  exceed  in  number  are 
called  supernumerary  teeth. 

Irregularity  in  time  of  appearance  is  equally  great. 
Teeth  have  been  seen  at  birth,  and  on  the  other  hand,  not 
till  ten  years  of  age.  These  may  be  regarded  as  the  ex- 
tremes, between  which  we  find  every  intermediate  shade  of 
variety. 

SECTION   III. 

ORIGIN    AND    DEVELOPMENT    OF    THE    TEETH,   AND    FORMATION   OF 
THE   ENAMEL. 

The  teeth  are  appendages  of  the  mucous  system,  and 
have  their  origin  from  the  mucous  membrane  of  the  mouth. 


ORIGIN  AND  DEVELOPMENT   OF  THE  TEETH.  249 


FIG.  71;        A 


B  Mr.  Goodsir's  obser- 

vations on  this  sub- 
ject being  the  most 
minute  and  accurate, 
we  will  very  briefly 
state  the  result  of  the 
facts  he  has  commu- 
nicated. 

His  observations 
began  in  an  embryo 
as  early  as  the  sixth 
week.  At  this  pe- 
riod the  superior 
maxillary  bone, 
within  its  external 
alveolar  margin, 
presents  a  deep,  nar- 
row groove.  This  he 
calls  the  primitive  dental  groove,  the  mucous  membrane 
lines  it.  In  the  seventh  week,  appears  upon  its  floor  a 

'*     •         y-  * 

FIG.  71,  A  represents  the  origin  and  progress  of  the  temporary  with  the 
corresponding  permanent  teeth,  after  Mr.  Goodsir.  a  Mucous  membrane, 
b  Mucous  membrane  containing  a  granular  mass,  c  Primitive  dental  groove. 
d  Papilla  on  the  floor  of  the  groove,  e  Papilla  enclosed  in  a  follicle.  /  Pa- 
pilla assuming  the  shape  of  a  pulp,  opercula  forming,  and  reserve  cavity  seen. 
g  Papilla  become  a  pulp  and  the  follicle  a  sac,  from  the  opercula  closing- 
h  Secondary  groove  adherent  except  behind  the  inner  operculum,  where  a 
closed  cavity  of  reserve  is  left  for  the  pulp  and  the  sac  of  the  permanent 
tooth,  i  Deposition  of  tooth  substance  commencing,  j  Cavity  of  reserve  re- 


250  ORIGIN  AND   DEVELOPMENT  OF  THE  TEETH. 

small  papilla,  which  is  the  germ  of  the  anterior  temporary 
molar.  In  the  eighth  week,  the  papillas  for  the  canine,  in 
the  tenth  those  for  the  incisors,  and  next  those  for  the 
posterior  temporary  molars  are  seen. 

This  is  styled  the  first  or  papillary  stage  of  development. 
Delicate  processes,  passing  from  the  sides  of  the  dental 
grooves,  meet  in  front  and  behind  the  papillae,  so  as  to  form 
an  open  follicle  for  each.  This  is  the  second  or  follicular 
stage,  which  is  not  completed  until  the  fourth  or  fifth 
month.  At  this  period  the  papillge  begin  to  change  their 
form  into  that  of  the  future  teeth. 

The  follicles,  which  are  still  open,  begin  now  to  be  closed, 
sending  from  their  edges  membranous  processes  across 
their  mouths,  called  opercula  or  lids.  Two  of  these  oper- 
cula  belong  to  the  incisors,  three  to  the  canine,  and  four 
or  five  to  the  molars.  The  complete  formation  of  these 
operculaa  constitutes  the  third  or  saccular  stage,  which 
commences  about  the  fourth  month  and  continues  to  the 
period  of  eruption — which  is  another  stage  called  the  erup- 
tive, and  already  described  in  another  place. 

During  the  saccular  stage  occur  some  of  the  most  inter- 
esting phenomena  in  dental  growth.  At  this  period  the 

ceding,  and  its  floor,  where  the  pulp  is  being  formed,  dilating,  fc  Cavity  of 
reserve  becoming  a  sac,  and  temporary  tooth  a  layer  of  bone.  I  Temporary 
tooth  rising  to  the  surface  of  the  gums  and  getting  a  fang,  m  Sac  of  the  tem- 
porary tooth  touching  the  surface  of  the  gums,  and  its  roots  elongated,  n  Sac 
of  the  temporary  tooth  again  become  a  follicle  by  its  eruption,  o  Completion 
of  the  sac,  and  its  free  portion  becoming  the  vascular  margin  of  the  gum,  and 
the  "  permanent  sac  connected  by  a  chord  passing  through  the  alveole  dental 
canal  or  foramen.'' 

FIG.  71,  B.  a  Non-adherent  portion  of  primitive  dental  groove,  b  Papilla 
and  follicle  upon  the  floor  of  this  non-adherent  portion,  now  become  a  part  of 
the  secondary  groove,  c  Papilla  become  a  pulp,  and  the  follicle  a  sac,  and 
cavity  of  reserve  seen,  d  Sac  of  first  molar  advancing  into  the  coronoid  pro- 
cess or  tuberosity  of  superior  maxilla,  and  increased  in  size,  e  Sac  of  first 
molar  having  resumed  its  former  position.  /  Cavity  of  reserve  sending  back- 
wards the  sac  of  the  second  molars,  g  Sac  of  second  molar  coming  into  the 
coronoid  process,  or  tuberosity  of  superior  maxilla,  h  Sac  of  second  molar 
returned  and  cavity  of  reserve  shortened,  i  Cavity  of  reserve  sending  offsac  and 
pulp  of  the  dens-sapientiaj  or  wisdom  tooth,  j  Sac  of  wisdom  tooth  advancing 
into  coronoid  process,  and  tuberosity  of  the  superior  maxilla,  k  Sac  of  the 
wisdom  tooth  returned  and  forming  the  last  of  the  dental  range. 


ORIGIN  AND   DEVELOPMENT  OF  THE  TEETH.  251 

papillae  become  pulps,  the  ivory  or  dentine  and  enamel 
are  formed,  the  enlargement  in  the  maxillary  bones,  and 
the  ossification  of  the  alveolar  processes  takes  place. 

The  rudiments  of  the  second  or  permanent  set  of  teeth 
are  developed  soon  after  the  commencement  of  the  saccular 
period.  The  papillae  and  sacs  of  the  ten  milk  teeth,  in  either 
jaw,  are  closed  about  the  fourteenth  week ;  and  the  upper 
or  superficial  part  of  the  primitive  groove  remains  open  and 
receives  the  name  of  the  secondary  dental  groove. 

It  is  in  this  groove  that  the  permanent  teeth  begin  their 
development.  Behind  the  operculum  of  each  milk  tooth 
sac  a  small  cavity  is  seen,  called  the  cavity  of  reserve.  The 
mucous  membrane  lines  this  cavity,  and  on  its  floor,  as  in 
the  primitive  groove,  a  papilla  is  formed  which  becomes 
enclosed  in  a  follicle  and  finally  in  a  shut  sac ;  as  this  is 
going  on,  the  papilla  is  found  to  recede  from  the  surface, 
and  the  neck  of  its  sac,  which  was  originally  continuous 
with  the  common  mucous  membrane,  remains  as  an  oblit- 
erated cord  connected  to  the  internal  surface  of  the  gum  of 
each  temporary  tooth.  These  cords  are  called  the  itinera- 
dentium.  About  the  fifth  month  the  papilla  and  follicle  of 
the  anterior  permanent  molar  is  developed  in  a  portion  of 
the  primitive  groove,  which  is  behind  the  posterior  tem- 
porary molar,  and  is  not  closed  so  soon  as  the  anterior 
portion. 

The  dental  groove,  in  closing  over  the  sac  of  this  anterior 
permanent  molar,  leaves  a  space  between  the  sac  and  the 
gum,  which  is  the  cavity  of  reserve  for  the  second  perma- 
nent molar,  and  a  similar  one  for  the  third  molar,  or  wis- 
dom tooth.  Owing  to  the  sacs  of  the  anterior  permanent 
teeth,  and  the  temporary  ones  enlarging  faster  than  the 
maxillary  bones  can  elongate,  the  cavity  for  the  permanent 
molars  recedes  into  the  root  of  the  coronoid  process  below, 
and  into  the  maxillary  tuberosity  above.  But  after  birth, 
as  the  jaw  enlarges,  the  first  permanent  molar  takes  its 
proper  place  and  level  in  the  dental  circle,  which  is  now 
occupied  by  the  cavity  of  reserve  dilating  in  it,  and  devel- 
oping in  it  the  papilla  of  the  second  permanent  molar.  In 


252       ORIGIN  AND  DEVELOPMENT  OF  THE  TEETH. 

time,  as  the  jaw  elongates  still  further,  this  molar  also  de- 
scends to  its  appropriate  place ;  and  then  the  remainder  of 
the  cavity  behind  dilates  for  the  development  of  the  dens 
sapientice. 

Ahout  the  fourth  or  fifth  month  of  intra-uterine  life, 
when  the  sacculated  stage  is  complete,  and  the  pulps  have 
taken  the  form  of  the  future  teeth,  we  find  the  growth  of 
the  dentine,  or  ivory,  commencing  by  being  deposited  first 
on  the  most  prominent  parts  of  the  surface  of  the  pulp,  as 
on  the  cutting  and  grinding  surfaces.  This  we  have 
already  explained  under  the  head  of  dentine. 

At  birth,  and  previous  to  it,  each  maxillary  bone  pre- 
sents, on  its  border,  a  whitish  and  dense  tissue  continuous 
with  the  gum ;  on  raising  it,  membranous  and  bony  septa, 
though  imperfect,  are  found  between  the  alveoli;  and  in 
the  latter  are  seen,  extending  from  this  fibrous,  white  tis- 
sue, prolongations  enclosing  the  dental  follicle  in  a  distinct 
sac,  which  is  perforated  at  the  bottom  for  the  vessels  and 
nerves  to  enter. 

On  examination,  these  dental  sacs  are  found  to  resemble 
serous  sacs,  and  to  hold  some  fluid.  Their  external  or 
parietal  layer,  being  fibro-cellular,  is  connected  with  the 
periosteum,  lines  the  alveolus,  and  is  reflected  from  the 
bottom,  round  the  vessels  and  nerves  over  the  pulp,  where 
it  is  called  the  tunica  propria.  It  is  highly  vascular,  no- 
ticed in  the  description  of  the  pulp.  This  reflected  portion 
was  originally,  in  the  follicular  stage,  mucous  membrane, 
which  the  papilla  and  pulp,  in  their  ascent  and  develop- 
ment carry,  or  push  before  it. 

It  has  been  stated  that,  on  the  surface  of  the  pulp,  the 
ivory  is  first  deposited;  and  that,  according  to  Mr.  Na- 
smyth's  discoveries,  the  superficial  set  of  cells  contained 
in  this  pulp  become  elongated,  and  are  first  formed  into 
tooth  bone ;  and  as  these  become  "calcified,"  the  layer  next 
beneath  takes  a  similar  arrangement,  is  in  like  manner 
formed  into  bone,  and  so  on,  layer  within  layer,  till  the 
greater  part  of  the  pulp  is  ossified.  In  this  way  a  complete 
shell  is  formed  for  the  pulp,  except  where  the  vessels  enter. 


FORMATION   OF   THE   ENAMEL.  253 

The  pulp  elongates,  sending  off  processes  to  form  the 
roots,  which,  in  their  descent,  continue  to  deposit  the  ivory 
around  them.  During  this  process,  previous  to  the  com- 
pletion of  the  outer  shell,  we  have  the  preparation  for  the 
formation  of  the  enamel. 

FORMATION   OF  THE  ENAMEL. 

A  diversity  of  opinion  is  entertained  as  to  the  manner  in 
which  the  enamel  is  formed.  The  doctrine  most  prevalent 
at  one  period,  was  that  the  inner  membrane  of  the  dental 
sac  made  a  deposition  of  the  enamel  fluid,  which  by  a  pro- 
cess of  condensation  resembling  crystallization,  ultimately 
attained  the  extreme  hardness  and  beautiful  polish  char- 
acteristic of  enamel. 

The  most  recent  observations,  however,  seem  to  prove 
that  there  is  an  especial  apparatus  provided  for  this  pur- 
pose, called  by  Raschkow,  the  adamantine  organ — and  by 
G-oodsir,  the  granular  substance,  which  is  described  as  being 
within  the  dental  sac,  and  becoming  gradually  absorbed  ; 
and  that  when  the  ivory  is  complete,  the  interior  of  this 
sac  is  observed  to  present  a  "  villous  and  vascular  appear- 
ance," having  a  thin  layer  of  this  granular  substance  upon 
it,  which  layer  is  regarded  as  the  enamel  organ  or  membrane, 
the  matrix  by  which  the  enamel  is  furnished. 

Professor  Harris  also  embraces  this  view  from  dissecting 
the  alveoli  of  a  pig,  and  afterwards  those  of  a  "  human 
foetus  at  the  fourth  month/'  where  he,  for  the  first  time, 
saw  this  granular  substance,  and  was  convinced  that  its 
office  was  the  furnishing  the  enamel,  and  that  his  previous 
views  were  incorrect.* 

The  microscope  of  Mr.  Nasmyth  demonstrates  that  the 
enamel,  as  well  as  the  ivory,  consists  of  cells,  and  that  it 
is  by  the  calcifying  of  these  cells  that  the  enamel  is  formed, 
the  deposit  being  first  made  on  the  prominences  of  the 
tooth,  then  over  the  surface  of  the  crown  and  body,  down 
to  the  neck,  where  it  ceases. 

*  See  Harris's  Principles  and  Practice  of  Dental  Surgery. 


254 


FORMATION  OF  THE  ENAMEL. 


The  enamel  is  represented  as  being  deposited  in  minute 
'particles  of  a  calcareous,  crystalline  character,  neither  very 
compact,  nor  firm,  but  soon  becoming  solid  and  strongly 
adhering  to  the  surface  of  the  ivory ;  its  fibres  being  p°er- 

pendicular  to  and 
having  a  different 
direction  from 
those  of  the  ivory. 
We  select  from 
Mr.  Nasmyth  the 
accompanying 
figure,  which 
shows  all  the  dif- 
ferent structures 
entering  into  the 
composition  of  a 
tooth,  as  the  blood 
vessels,  pulp,  cells 
of  pulp,  their  con- 
version into  den- 
3  tine,  enamel,  and 
cementum,  at  a 
single  glance,  and 
which  we  have 
introduced  here 
at  the  close  of 
their  description, 
in  order  that  a 
proper  estimate 
may  be  formed  of 
this  gentleman's 
views  of  the  mode 
in  which  teeth  are 
formed. 

FIG.  72,  1  1  Blood  vessels  and  capillaries  of  the  pulp.  2  2  Cells  in  pro- 
cess of  conversion  into  ivory  or  dentine.  3  3  Line  showing  the  transition  of 
these  cells  into  the  structure  of  dentine  more  clearly.  4  4  The  dentine.  5  5 
Enamel.  6  6  Cortical  substance  or  crusta  petrosa. 


CHANGES  PRODUCED  ON  THE  FACE.          255 


CHANGES  PRODUCED  ON  THE  UPPER  AND  LOWER  JAW  AND  FACE, 
FROM  THE  DEVELOPMENT  OF  THE  TEETH. 

During  the  period  of  the  first  and  second  dentition,  great 
and  obvious  changes  are  noticed  in  the  face,  resulting  from 
changes  occurring  in  the  upper  and  lower  jaw  bones,  from 
development  of  the  teeth. 

The  principal  of  these  changes  we  will  briefly  notice,  to 
impress  upon  the  student  the  great  and  commanding  in- 
fluence which  the  teeth  simply  exert  during  their  develop- 
ment, in  producing  the  various  configurations  of  the  face, 
observed  at  different  periods.  The  first  we  notice  is  in  the 
dental  arches.  The  maxillary  bone,  as  stated  in  another 
place,  presents  in  the  first  instance  a  simple  groove,  scarcely 
perceptible  when  the  tooth  germs  are  present,  but  which 
soon  becomes  partitioned  off  and  formed  into  alveoli  for  the 
accommodation  of  the  two  sets  of  teeth.  After  the  per- 
manent set  have  completed  their  eruption,  we  find  but  a 
single  range  of  alveoli ;  and  when,  as  in  old  age,  the  teeth 
are  lost,  the  alveoli  are  destroyed  and  the  arches  again  re- 
turn to  their  original  embryo  state. 

The  alveolar  arches,  when  the  teeth  are  being  developed, 
show  striking  changes  in  their  length  and  height.  The 
length  of  the  arches  depends  upon  the  volume  and  number 
of  the  teeth,  and  Blandin  says  it  may  be  safely  asserted 
that  the  arches  grow  from  the  "  beginning  of  life,"  to  the 
full  development  of  the  dens-sapientae.  These  arches,  in 
the  adult,  are  separated  by  drawing  a  transverse  line  in 
front  of  the  first  molar,  into  an  anterior  and  a  posterior 
portion. 

All  the  alveoli  belong  to  the  first  portion  till  the  appear- 
ance of  the  first  permanent  molar  in  the  fifth  year.  The 
alveolar  arch  now  extends  itself  back  to  make  room  for 
the  second  molar  and  wisdom  teeth,  and  on  their  appear- 
ance, the  anterior  and  posterior  portions  are  of  equal 
length. 

The  changes  in  height  of  the  alveolar  arches,  seem  to 
be  regulated  by  the  development  of  the  roots  of  the  teeth. 


256  CHANGES  PRODUCED   ON  THE  FACE. 

About  the  fifth  or  sixth  year,  Blandin  makes  the  arches  to 
attain  their  maximum  height ;  and  as  we  depart  from  this 
period,  either  forward  or  backward,  they  "gradually  di- 
minish." 

The  base  of  the  lower  jaw  exhibits  changes  during  the 
development  of  the  teeth ;  being  arched  upwards  and  back- 
wards in  the  young  and  the  aged,  but  lying  horizontal  in 
the  adult.  The  angle  of  the  lower  jaw  is  very  obtuse  in 
the  foetal  and  young  subject ;  in  the  adult  it  contracts  to 
a  right  angle ;  while  in  old  age  it  again  opens,  or  returns 
to  the  infantile  state.  The  mental  prominence,  in  the  infe- 
rior maxilla,  is  most  projecting  when  the  angle  is  obtuse, 
as  in  the  young  and  the  aged ;  while  in  the  nearly  right 
angle  of  the  adult  it  is  much  less  so.  The  condyloid  and 
coronoid  processes,  instead  of  presenting  the  vertical  di- 
rection of  the  adult,  look  backwards  and  upwards  in  the 
child,  and  the  very  aged.  The  coronoid  processes  in  the 
young,  are  higher  than  the  condyloid ;  in  the  adult,  they 
are  nearly  on  the  same  level ;  and  in  the  aged  they  again 
return  to  their  early  state. 

The  inferior  dental  canal  does  not  exist,  except  in  the 
form  of  the  rudimentary  groove,  at  the  earliest  periods ;  it 
becomes  developed  when  the  alveoli  are  formed. 

This  canal  occupies,  in  the  adult,  about  the  middle  point 
between  the  alveolar  arch,  and  the  base  of  the  lower  jaw. 
It  is  said  to  be  situated  precisely  at  the  lower  portion  of 
the  alveoli,  in  the  young  subject;  and  in  the  aged,  it  is 
found  at  the  superior  border  from  the  loss  of  the  alveoli. 
In  first  dentition  it  is  large,  and  gradually  disappears  on 
the  shedding  of  the  teeth. 

The  anterior  dental  or  mental  foramen,  according  to  Mr. 
Duval,  is  situated,  at  birth,  near  to  the  symphysis ;  and  in 
proportion  to  the  development  of  the  teeth,  is  carried  back- 
wards. At  first,  it  is  between  the  canine  and  first  molar. 
When  the  milk  teeth  are  fully  developed,  it  is  more  poste- 
rior ;  and  on  the  appearance  of  the  large  molars,  it  occupies 
the  point  between  the  two  temporary  molars,  or  future 
bicuspids. 


CHANGES  PRODUCED  ON  THE  FACE.  257 

The  infra  orbital  foramen  of  the  upper  jaw  presents  sim- 
ilar changes.  It  is  found,  at  birth,  to  correspond  with  the 
point  between  the  canine  and  first  molar;  after  this,  to 
become  more  posterior  on  the  completion  of  first  dentition; 
and  when  the  first  permanent  molaris  appears,  to  occupy 
the  usual  adult  point,  namely,  on  a  line  between  the  two 
bicuspids. 

T he  pterygoid process es  of  the  sphenoid  are  also  affected, 
and  undergo  changes  during  the  development  of  the  teeth. 
M.  Blandin  says  these  processes  are  to  the  superior  dental 
arch,  what  "the  posterior  border  and  angle  are  to  the 
inferior."  Both  are  alike  points  of  support  to  the  alveolar 
arches;  and  both  also  undergo  similar  changes  in  the 
development  of  the  teeth.  At  birth  these  processes,  like 
the  posterior  of  the  lower  jaw,  look  very  obliquely,  for- 
wards and  downwards.  In  the  adult  they  take  the  verti- 
cal position;  and  in  old  age  they  again  return  to  their 
primitive  oblique  condition. 

The  maxillary  tuberosity  also  undergoes  important 
changes  during  the  development  of  the  teeth.  Before  the 
time  of  their  eruption,  this  tuberosity  is  large,  from  lodg- 
ing the  greater  molars ;  but  after  their  appearance,  it  in  a 
great  measure  disappears,  and  still  can  be  seen  to  exist, 
notwithstanding  M.  Blandin's  opinion  to  the  contrary. 

The  roots  of  the  superior  middle  molars  of  the  upper 
jaw  exert  a  decided  influence  upon  the  floor  of  the  max- 
illary sinus.  In  the  rudimentary  state  their  action  is  not 
very  great.  But  in  the  adult  period,  when  the  sinus  is 
large  and  the  roots  fully  developed,  we  sometimes  find 
these  roots  entering  this  sinus,  a  fact  of  great  practical 
importance  in  the  treatment  of  its  diseases ;  while,  in  old 
age,  we  are  told  the  sinus,  "by  a  new  development,  has  its 
floor  carried  back  from  the  roots  of  the  teeth,"  whose  action 
upon  the  sinus  is  already  diminished  by  the  contraction  of 
the  alveoli. 

Now  all  these  changes  upon  the  upper  and  lower  jaw, 
during  the  development  of  the  teeth,  it  will  be  readily 
perceived,  must  exert  a  most  powerful  influence  on  the 
17 


258  VARIETIES  IN  THE  TEETH. 

configuration  of  the  face.     This  is  so  manifest  that  we 
deem  any  further  remarks  on  the  subject  unnecessary. 

FUNCTIONAL  RELATIONS  OF  THE  TEETH. 

The  relations  of  the  teeth,  in  their  healthy  functional 
action,  are  varied,  and  are  of  great  importance.  They  are, 
in  the  first  place,  the  immediate  instruments  in  mastica- 
tion—a process  forming  one  of  the  essential  and  prelimi- 
nary steps  in  the  function  of  digestion.  By  the  incisors 
the  food  is  divided ;  by  the  canine  it  is  torn  in  pieces ;  and 
by  the  molars  it  is  compressed,  triturated,  and  reduced  to 
still  smaller  fragments  adapted  to  the  digestive  powers  of 
the  stomach. 

The  teeth  also  form  a  wall  or  hedge,  nicely  suited  to 
retain  the  saliva  and  other  fluids  in  the  mouth.  They  aid 
in  articulation.  All  know  how  the  loss  of  the  teeth  affects 
the  pronunciation ;  how  the  sounds  are  less  clear  and  dis- 
tinct, and  speech  becomes  often  fatiguing,  difficult,  and 
unintelligible.  The  incisors  are  of  more  importance  in 
articulation  than  any  others;  next  in  order  are  the  ca- 
nine ;  and  lastly,  the  molares. 

They  also  conduct  impressions  to  the  brain,  by  trans- 
mitting them  to  the  fifth  and  auditory  nerves;  and,  finally, 
in  some  of  the  lower  animals  they  form  the  principal 
weapons  of  defence,  as  well  as  of  attack. 

The  teeth  are  connected,  directly  or  indirectly,  with  the 
whole  body,  and  all  its  organs  and  functions.  We  there- 
fore postpone  any  further  remarks  on  their  relations,  till 
the  several  organs  shall  have  come  under  examination. 

VARIETIES  IN  THE  TEETH. 

These  varieties  are  multiplied,  and  have  been  arranged 
in  reference  to  the  age,  the  individual,  and  the  race. 

Under  the  head  of  development,  much  has  already  been 
said  as  to  the  appearance  of  the  teeth  at  different  ages. 
We  will  therefore  simply  remark,  in  the  language  of  Mr. 
Blandin:  "In  the  very  young  child  the  crown  is  formed 
before  the  ossification  of  the  root  commences.  At  an  age  a 


BLOOD-VESSELS  OF  THE  TEETH.  259 

little  more  advanced  the  crown  of  the  tooth  is  beginning 
to  wear  away  before  the  root  is  entirely  completed.  In 
the  adult  the  crown  has  lost  its  points  and  the  root  at- 
tained its  full  development.  Finally,  in  old  persons,  the 
crown  is  sometimes  completely  worn  away,  whilst  the  root 
still  remains  almost  in  a  perfect  state."  The  destruction 
of  the  teeth  is  therefore  regarded  as  a  useful  criterion  in 
determining  the  age. 

The  individual  varieties  of  teeth  are  numerous,  and  refer 
to  their  number,  situation,  form,  direction,  and  structure, 
already  treated  under  the  head  of  irregularities  of  the  teeth, 
which  see. 

The  varieties  according  to  race  are  extremely  limited. 
The  blacks  have  them,  it  is  considered,  somewhat  larger, 
longer,  and  more  oblique  than  the  white.  As  to  the  cus- 
tom of  staining  and  filing,  which  some  nations  adopt,  such 
habits  cannot  properly  be  considered  under  the  head  of 
varieties. 

SECTION    IV. 
BLOOD-VESSELS  OF  THE  TEETH.    (Fig.  fS.) 

The  arteries  supplying  the  teeth  come  from  the  internal 
maxiilcfry.  This  is  a  branch  of  the  external  carotid.  The 
external  carotid  is  one  of  the  two  divisions  of  the  common 
carotid,  and  extends  from  the  top  of  the  larynx  to  the  neck 
of  the  condyle  of  the  loiverjaw,  and  meatus  auditorium  externus. 

It  is  at  the  upper  part  of  the  larynx  or  thyroid  cartilage 
that  the  common  carotid  arteries  make  their  division  into 
external  and  internal  carotid. 

The  common  carotids  (*opa,  the  head,  <n>j,  the  ear,)  arise 
low  down  in  the  neck  at  its  base.  The  right  common  ca- 
rotid comes  from  the  arteria  innominata,  the  left  from  the 
arch  of  the  aorta.  Both  ascend  the  neck,  covered  first  by 
iheplatysma  and  superficial  fascia,  along  the  inner  margin 
of  the  sterno-cleido  mastoid  muscles,  to  the  top  of  the  thyroid 
cartilage,  where,  as  we  have  just  stated,  they  divide  into 
the  external  and  internal  carotids. 


260 


BLOOD-VESSEL  OF  THE  TEETH. 


FlG-  73t        A  The    external    gives   off 

several  branches.  The  in- 
ternal maxillary,  however, 
is  the  only  one  claiming 
attention  in  the  present 
place.  To  expose  this  ves- 
sel, the  zygomatic  arch 
should  be  sawn  through 
at  each  end,  and  turned 
down.  The  temporal  mus- 
cle is  to  be  divided  at  its 
insertion  into  the  coronoid 
process,  and  turned  up. 
The  ramus  of  the  jaw  di- 
vided in  its  middle,  disar- 
ticulated and  removed,  the 
vessel  is  now  brought  to 
view. 

It  will  be  seen  to  com- 
mence in  the  substance  of 
the  parotid  gland,  near  the 
meatus    externus,    to    pass 
obliquely  forwards  behind 
the  neck  of  the  lower  jaw; 
then  between  the  two  pter- 
yyoid  muscles, 
often  winding 
round  the  out- 
er   surface    of 
the    external 
pterygoid  at 
its     origin. 
From    this    it 

proceeds   to   the  tuberosity  of  the   superior  maxilla,  and 
finally  bends  down   into  the  pterygo  maxillary  fossa,  to 

FIG.  73,  A  represents  the  arteries  supplying  one  side  of  the  face  and  mouth. 
1  1  External  carotid  artery.  2  Inferior  maxilla  with  its  exterior  wall  re- 
moved, so  as  to  expose  the  inferior  dental  artery,  and  roots  of  the  teeth. 


BLOOD-VESSELS  OF  THE  TEETH.  261 

terminate  by  sending  off  several  brandies.     Its  branches 
supplying  the  teeth  are, 

1.  The  superior  dental  or  alveolar. 

2.  Infra  orbitar. 

3.  Inferior  dental  or  maxillary. 

The  superior  dental  artery  comes  off  from  the  internal 
maxillary,  at  its  entrance  into  ihepterygo  maxillary  fossa; 
it  then  winds  round  the  maxillary  tuberosity,  sending 
branches  through  the  posterior  dental  canals  to  supply  the 
molares  and  the  antrum,  and  finally  proceeds  forward  upon 
the  alveolar  processes,  supplying  their  cavities,  and  the 
gums.  Those  branches  going  to  the  teeth  enter  by  the 
foramen  at  the  apex  of  the  roots,  and  are  distributed  over 
the  pulps. 

The  infra-orbital  artery  arises  from  the  internal  maxil- 
lary in  the  upper  part  of  the  pterygo  maxillary  fossa,  enters 
the  infra  orbital  canal,  traverses  its  whole  extent  along 
with  a  nerve  of  the  same  name,  and  emerges  upon  the 

3  Posterior  mental  foramen,  which  gives  passage  to  the  inferior  dental  artery. 

4  Anterior  mental  foramen,  where  the  same  artery  makes  its  exit.    5  5  The 
anterior  and  inferior  wall  of  the  superior  maxilla  removed,  so  as  to  exhibit 
the  antrum,  roots  of  the  teeth,  and  arteries  supplying  each.     6  Infra-orbitar 
foramen,  for  the  passage  of  the  infra-orbitar  vessels.     8  Nasal  process  of  su- 
perior maxilla.    9  Pterygoideus  intejnus  muscle.     10  Angle  of  inferior  max- 
illary bone.     11  Orbit  of  the  eye.     12  Superior  thyroid  artery.     13  13  Facial 
artery.     14  Terminating  branch  of  the  lingual.     15  Where  the  external  carotid 
terminates  by  dividing  into  the  internal  maxillary  and  temporal.     16  Temporal 
artery.    17  Internal  maxillary.    18  18  Inferior  dental  artery.    19  Deep  temporal 
branch.    20  Transverse  artery  of  the  face.    2121  Muscular  branches.    22  Alve- 
olar branch.     23  Posterior  dental  branch.     24  Where  the  infra  orbital  artery 
terminates.     25  Nasal  branch  of  the  facial.    26  Sub-mental  branch. 

FIG.  73,  B  represents  chiefly  the  external  carotid  artery,  and  its  branches 
which  supply  the  exterior  head,  face,  and  part  of  the  neck.  1  Common  ca- 
rotid artery.  2  External  carotid.  3  Internal  carotid.  4  Superior  thyroid. 

5  Lingual.    6  Facial  branches  of  external  carotid.    7  Sub-mental.    8  Inferior 
coronary.     9  Superior  coronary  branches  of  facial.     10  Occipital.     11  Infe- 
rior pharyngeal  branches  of  external  carotid.    12  12  13  Branches  of  occipital. 
14  Posterior-auricular  branch  of  external  carotid.     15  Transverse  facial.     16 
Posterior  temporal.     17  Middle  temporal.     18  Anterior  temporal  branches  of 
the  temporal  artery.     19  Supra  orbitar,  a  branch  of  the  ophthalmic.     20  Sub- 
clavian,  a  branch  of  the  arteria  innominata  on  the  right,  and  the  aorta  on  the 
left. 


262  BLOOD-VESSELS  OF  THE  TEETH. 

face  at  the  infra  orbital  foramen,  anastomosing  with  the 
facial  and  transverse  facial  arteries.  Just  before  it  emerges, 
it  sends  down,  in  the  anterior  dental  canal,  a  branch  to 
supply  the  incisors  and  cuspidati,  and  also  the  lining 
membrane  of  the  antrum. 

The  inferior  dental  arises  from  the  internal  maxillary 
behind  the  neck  of  the  lower  jaw,  descends  to  the  poste- 
rior mental  foramen,  which  it  enters  along  with  the  dental 
nerve;  thence  it  passes  along  the  canal  beneath  the  roots 
of  the  teeth,  sending  up  into  each,  in  its  course,  small 
twigs  which  supply  the  molars.  When  opposite  the  bicus- 
pid, it  divides  into  two  branches — the  one  being  the  con- 
tinued trunk  which  proceeds  forwards  to  the  symphysis, 
supplying  the  anterior  teeth,  while  the  second  branch 
passes  out  at  the  anterior  mental  foramen,  upon  the  side 
and  front  of  the  chin,  anastomosing  with  branches  of  the 
facial  artery. 

The  internal  maxillary  vein,  made  up  of  the  veins  corre- 
sponding to  the  several  branches  of  the  internal  maxillary 
artery,  returns  the  blood  of  the  artery,  and  passing  behind 
the  neck  of  the  jaw,  unites  in  the  substance  of  the  parotid 
with  the  temporal  vein — the  junction  of  the  two  mainly 
forming  the  external  jugular,  which  passes  superficially 
down  the  neck,  to  terminate  in  the  subclavian  vein. 

THE  NERVES  OF  THE  TEETH.   (Fig.   *74.) 

The  nerves  supplying  the  teeth  come  from  the  fifth  pair, 
and  are  nerves  of  sensation.  The  fifth  nerve  can  be  traced 
to  the  spinal  cord,  having  its  roots  in  the  anterior  and  pos- 
terior columns  ;  hence  it  is  called  the  cranial-spinal  nerve. 
Being  a  spinal  nerve,  it  has  on  its  posterior  root  a  ganglion, 
and  the  junction  of  the  anterior  and  posterior  roots  consti- 
tutes properly  the  fifth  nerve.  It  is  seen  to  emerge  at  the 
.side  of  the  Pons-varolii  on  the  anterior  part  of  the  cms- 
cerebelli.  At  this  point  it  is  composed  of  from  80  to  100 
filaments,  which  pass  forward  in  a  canal  of  the  dura-mater 
upon  the  anterior  surface  of  the  petrous  bone,  in  a  depres- 
sion of  which  it  expands  into  a  ganglion  called  the  Gasse- 


THE  NERVES  OF  THE  TEETH. 


263 


rian  ganglion.  On  the  under  surface  of  this  ganglion  is 
seen  the  anterior  root,  having  no  connection  with  it  and 
being  the  motor  portion. 

From  the  gasserian  ganglion  proceed  three  branches, 

1.  The  ophthalmic, 

2.  The  superior  maxillary, 

3.  The  inferior  maxillary  nerve. 


FIG.  74. 


The  two  latter  furnish  the  branches  supplying  the  teeth. 
The  superior  maxillary  nerve 
arises  from  the  middle  of  the 
ganglion  of  Gasser,  passes 
forwards  through  the  fora- 
men rotundum  of  the  sphenoid 
bone,  into  the  pterygo-max- 
illary  fossa — at  this  point  it 
sends  off  several  branches, 
two  of  which  descend  to  join 
the  ganglion  of  Meckel.  The 
main  trunk  is  continued  for- 
ward with  the  artery  in  the 
infra  orbital  canal,  as  the  in- 
fra orbital  nerve}  and  finally 
emerges  at  the  infra  orbital 
foramen  between  the  levator 
labii  superioris  alasque  nasi, 
and  levator  anguli  oris  muscles,  anastomosing  with  the 
nasal  branch  of  the  ophthalmic,  and  the  portio-dura  of 

FIG.  74  represents  the  distribution  of  the  fifth  pair,  or  Trifacial  Nerve,  and 
especially  those  branches  supplying  the  teeth. 

1  Orbit ;  2  Maxillary  sinus,  or  antrum  of  Highmore ;  3  Tongue ;  4  Infe- 
rior maxilla;  5  Root  of  fifth  pair,  forming  the  ganglion  of  Gasser;  6  Oph- 
thalmic, or  first  branch  of  the  fifth ;  7  Superior  maxillary,  or  second  branch 
of  the  fifth ;  8  Inferior  maxillary,  or  third  branch  of  the  fifth ;  9  Frontal 
branch  ;  10  Lachrymal  branch;  11  Nasal  branch,  which  latter,  with  9  and 
10,  are  branches  again  of  the  first  or  ophthalmic  division  of  the  fifth ;  12 
Internal  nasal  nerve  going  through  the  anterior  ethmoid  foramen;  13  Ex- 
ternal nerve  ;  14  External  and  internal  frontal  nerve  ;  15  Infra  orbitar  nerve  ; 
16  Posterior  dental  nerves;  17  Middle  dental  branch;  18  Anterior  dental 


264  THE  NERVES  OF  THE  TEETH. 

the  seventh.  The  infra  orbital  nerve,  just  before  emerging., 
sends  down  in  the  anterior  dental  canal ,  in  front  of  the 
antrum,  the  anterior  dental  nerve,  which  gives  off  filaments 
to  supply  the  incisors,  canines,  and  bicuspids  of  the  upper 
jaw,  as  well  as  the  lining  membrane  of  the  antrum.  These 
accompany  the  arterial  twigs  and  enter  the  apex  of  the 
roots  in  a  similar  manner.  An  anastomosis  occurs  between 
the  anterior  and  posterior  dental  nerves.  The  posterior 
dental  nerves  come  off  from  the  superior  maxillary  in  the 
pterygo  maxillary  fossa;  they  consist  of  two  or  three 
branches,  which  enter  the  posterior  dental  canals  upon  the 
tuberosity  of  the  superior  maxillary  bone,  and  supply  the 
molares,  the  contiguous  gums,  and  buccinator  muscle. 

The  superior  maxillary  nerve  is  connected  with  the 
ganglion  of  Meckel,  called  also  spheno-palatine,  from  which 
three  sets  of  branches  are  found  to  proceed — the  one  pass- 
ing downwards,  the  inferior,  the  second  going  backwards, 
the  posteriory  while  the  third  proceeds  inwards,  and  is  the 
internal  set. 

The  ganglion  of  Meckel  is  situated  in  the  ptery go-maxil- 
lary fossa  between  the  pterygoid  processes  and  the  tuber- 
osity of  the  superior  maxilla,  surrounded  by  adipose  mat- 
ter and  branches  of  the  internal  maxillary  artery.  The 
first  set  of  branches,  the  inferior,  proceeding  from  this 
ganglion,  descend  the  posterior  palatine  canal.  They  are 
four  or  five  in  number  and  receive  the  name  of  the  palatine 
nerves.  As  they  approach  the  palate  they  divide  into  an 
anterior,  posterior,  and  middle  set  of  filaments;  the  ante- 
rior proceeds  forwards  above  the  mucous  membrane  in  a 
groove  on  the  inside  of  the  alveoli,  supplying  these  parts, 
while  the  posterior  and  middle  are  distributed  to  the  soft- 
palate,  tonsils,  and  uvula. 

nerve ;  19  Terminating  branches  of  infra  orbital ;  20  Orbitar  branch  upon 
the  malar  bone ;  21  Pterygoid  branches  from  Meckel's  ganglion  ;  22  Ante- 
rior branches  of  the  inferior  maxillary,  or  third  division  of  the  fifth  ;  23 
Lingual  or  gustatory  branch  of  the  inferior  maxillary,  joined  by  the  chorda 
tympani ;  24  Inferior  dental  nerve,  and  branches  supplying  the  teeth ;  25 
Mental  branches ;  26  Superficial  temporal  nerve  ;  27  Auricular  branches ; 
28  Mylo-hyoid  branch. 


THE  NERVES  OF  THE  TEETH.  265 

The  posterior  branch,  called  the  pterygoid  or  vidian* 
passes  from  the  ganglion  of  Meckel  in  the  backward  direc- 
tion, through  the  vidian  canal  at  the  root  of  the  pterygoid 
process,  then  enters  the  cranium  through  the  foramen 
lacerum  medius,  and  divides  into  an  inferior  and  superior 
branch.  The  former,  called  the  carotid  branch,  enters  the 
cavernous  sinus  and  unites  with  the  plexus  surrounding 
the  carotid  artery,  formed  by  the  ascending  branches  of 
the  superior  cervical  ganglion.  The  superior  branch  rep- 
resents rather  the  continued  trunk  of  the  vidian,  and 

*  Very  great  confusion  of  description  and  wide  diversity  of  opinion  prevail 
among  anatomists  in  regard  to  this  nerve  and  its  connections.  By  some  it  is 
regarded  as  a  sensory  nerve,  coming  off  from  the  fifth  pair.  By  others  it  is  con- 
sidered as  a  sympathetic  nerve  originating  from  Meckel's  ganglion,  and  binding 
together  the  various  superficial  and  deep  nerves  of  this  region. 

Before  its  entrance  into  the  hiatus  fallopii,  it  is  found  to  connect  itself  by 
filaments  with  many  nerves  at  the  base  of  the  skull,  entering  the  hiatus.  It  is 
ordinarily  described  as  uniting  with  the  facial  at  its  angle,  where  the  intu- 
mescentia  genuformis  (or  gangliformis)  is  found.  The  researches  of  Morganto, 
Brinton,  and  Malagati,  show  that  this  intumescence  does  not  belong  to  the 
facial,  but  to  a  third  division  of  the  old  seventh  nerve,  first  described  by  Mis- 
berg,  and  called  by  him  porlio  intermedia,  because  it  lies  between  the  facial 
and  auditory  nerves.  It  is  clearly  traced  into  the  medulla  oblongata  in  one 
direction,  and  into  this  geniculate  ganglion  in  the  other.  Malagati  infers  from 
his  recent  investigations  that  this  portio  intermedia  is  really  a  nerve  of  organic 
life,  entering  the  brain,  and  associating  the  ear  with  that  viscus  as  well  as  with 
the  viscera  of  the  thorax  and  abdomen — a  theory  which  accounts  for  the  re- 
markable sympathies  known  to  exist  between  the  ear  and  these  various  organs, 
how  it  is  with  this  geniculate  ganglion,  that  the  superior  branch  of  the  vidian 
(nervus  petrosus  superficialis  major  of  Arold)  is  connected.  With  it  also  is  joined 
the  nervous  petrosus  superficialis  minor,  which  may  be  regarded  either  as  a  branch 
of  the  optic  ganglion,  or  of  the  tympanic  plexus.  In  any  case,  however,  it  con- 
nects the  glosso-pharyngeal  with  this  petrosal  branch  of  the  vidian,  through  the 
medium  of  Jacobson's  nerve. 

From  this  same  geniculate  ganglion,  which  thus  appears  to  be  a  highly  im- 
portant sympathetic  centre,  the  chorda  tympani  comes  off',  and,  as  described  in 
the  text,  passes  through  the  Glasserian  fissures  and  unite  itself  with  the  gusta- 
tory branch  of  the  fifth  pair.  It  seems  to  exercise  an  influence  upon  the  sense 
of  taste  ;  for  impairment  of  this  function  always  occurs  when  the  facial  js  in- 
jured, when  its  injury  can  involve  those  of  the  chorda  tympani. 

The  termination  of  the  chorda  tympani  has  been  stated  according  to  the 
views  of  the  English  anatomists.  It  cannot,  however,  be  wholly  traced  into 
the  submaxillary  ganglion.  Some  anatomists  have  failed  entirely  to  establish 
the  connection.  Guarini  traces  it  into  the  lingualis  muscle.  At  most,  only  a 
portion  of  the  nerve  can  be  connected  with  this  ganglion. 


266  THE  NERVES  OP  THE  TEETH. 

passes  beneath  the  ganglion  of  Gasser  and  the  dura  mater, 
outwards  and  backwards  upon  the  anterior  cerebral  sur- 
face of  the  petrous  bone,  to  the  hiatus  fallopii,  which  it 
enters.  In  this  canal  it  joins  the  portio  dura,  and  accom- 
panies this  latter  nerve  to  the  posterior  part  of  the  tympa- 
num, where  it  then  leaves  the  portio  dura  by  entering  the 
cavity  of  the  tympanum,  and  here  receives  the  name  of 
chorda  tympani.  Its  entrance  into  the  tympanum  is  below 
the  pyramid,  and  from  this  point  it  crosses  the  cavity  be- 
tween the  long  leg  of  the  incus,  and  handle  of  the  malleus; 
then  it  emerges  along  with  the  tendon  of  the  laxator  tym- 
pani  muscle  by  the  glenoid  fissure,  and  now  runs  forwards 
and  inwards,  joining  in  its  course  the  gustatory  nerve  as 
far  as  the  submaxillary  gland,  at  which  point  it  joins  the 
submaxillary  ganglion.  This  ganglion  is  found  at  the 
posterior  part  of  the  submaxillary  gland. 

The  vidian  nerve,  by  this  lengthy  and  circuitous  course, 
establishes,  says  Mr.  Harrison,  several  very  interesting  re- 
lations :  by  it,  the  ganglion  of  Meckel,  the  superior  cervi- 
cal ganglions  of  the  sympathetic,  and  the  submaxillary 
ganglion,  are  all  connected.  It  also  unites  the  superior 
and  inferior  maxillary  nerves,  and  both  to  the  portio  dura. 

The  third  set  of  branches  from  Meckel's  ganglion  pass 
inwards,  and  are  called  the  nasal  or  spheno-palatine.  These 
(often  only  a  single  branch)  pass  through  the  spheno- 
palatine  foramen  and  then  separate  into  five  or  six  branches, 
which  supply  the  mucous  membrane  of  the  upper  and  mid- 
dle spongy  bones.  One  long  branch,  called  the  nerve  of 
Cotunnius  or  naso-palatine,  is  seen  to  descend  along  the 
septum-nasi  as  far  as  the  foramen  incisivum,  at  which 
point  it  meets  the  anterior  branches  of  the  palatine  nerves, 
and  also  here  a  small  ganglion  is  spoken  of,  but  difficult 
to  be  distinguished. 

An  orbital  branch  comes  off  next  from  the  superior  maxil- 
lary, this  gets  into  the  orbit  through  the  spheno-maxillary 
fissure,  and  there  divides  into  a  temporal  and  a  molar 
branch.  The  former  is  traced  through  the  malar  bone  into 
the  temporal  fossa,  accompanies  the  temporal  artery,  and 


THE  NERVES  OF  THE  TEETH.  267 

is  spent  upon  the  side  of  the  head  and  temple  ;  the  malar 
branch  also  passes  through  the  malar  hone  and  is  dis- 
tributed to  the  muscles  and  integuments  upon  this  hone. 

The  inferior  maxillary  nerve  forms  the  third  and  largest 
division  of  the  fifth.  It  arises  from  the  lower  portion  of 
the  Gasserian  ganglion,  passes  through  the  foramen  ovale 
of  the  sphenoid  bone,  and  as  it  leaves  this  foramen  unites 
with  the  motor  root,  and  then  divides  into  two  branches, 
an  external  or  superior,  and  internal  or  inferior. 

The  inferior  gives  off  the  branch  which  supplies  the  teeth 
of  the  lower  jaw.  This  is  the  inferior  dental  nerve.  It 
separates  from  the  gustatory  nerve,  and  descends  between 
the  pterygoid  muscles,  along  the  ramus  of  the  lower  jaw 
to  the  posterior  dental  foramen  into  which  it  enters.  It  now 
proceeds  along  the  canal  in  the  inferior  maxillary  bone, 
supplying  the  teeth  in  its  course  to  the  anterior  dental  fo- 
ramen through  which  it  emerges,  and  is  distributed  to  the 
muscles  and  integuments  of  the  lower  lip  and  chin ;  at  this 
latter  foramen  a  small  branch  is  continued  forward,  the 
incisive  branch,  to  supply  the  incisor  teeth. 

The  mylo-hyoideus  is  the  only  branch  generally  given  off 
by  the  inferior  dental  nerve.  It  comes  off  at  the  posterior 
dental  foramen  and  passes  along  a  groove  on  the  inferior 
maxillary  bone,  to  the  mylo-hyoid  and  digastric  muscles. 

The  gustatory  is  the  next  in  size  of  the  internal  or  lower 
division  of  the  inferior  maxillary.  It  connects  with  the 
inferior  dental,  and  is  joined  by  the  chorda-tympani  soon 
after  this  junction.  It  descends  between  the  ramus  of  the 
lower  jaw  and  the  internal  pterygoid  muscle;  proceeds  ob- 
liquely forwards  above  the  submaxillary  gland  and  mylo- 
hyoid  muscle,  accompanied  by  the  duct  of  Wharton,  and  is 
distributed  to  the  lateral  and  anterior  parts  of  the  tongue. 
The  gustatory  gives  off,  in  this  course,  filaments  to  the 
pterygoideus  internus,  the  pharynx,  tonsils,  muscles  of  the 
palate  and  the  gums,  as  well  as  communicating  branches 
with  the  lingual. 

The  auricular  is  the  smallest  branch  of  the  inferior  divis- 
ion, it  passes  posterior  to  the  neck  of  the  lower  jaw  and  in 


268  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

front  of  the  meatus  externus,  supplying  the  articulation  of 
the  jaw,  the  meatus  auditorius,  the  cartilages  of  the  ear,  and 
then  mounting  over  the  zygoma,  divides  into  anterior  and 
posterior  branches;  which  follow  the  course  of  the  temporal 
artery.  This  nerve  connects  with  the  facial.  The  superior 
division  of  the  inferior  maxillary  nerve  has  the  motor 
trunk  and  divides  into  the  masseter,  the  deep  temporal,  the 
buccal,  and  ihepterygoid  branches. 

The  masseter  nerve  passes  in  front  of  the  neck  of  the 
lower  jaw  and  the  insertion  of  the  temporal  muscle,  through 
the  sigmoid  notch,  and  is  distributed  to  the  masseter  mus- 
cle. The  deep  temporal  nerves  ascend  to  the  temporal  mus- 
cle, in  which  they  are  lost.  They  are  two  in  number,  an 
anterior  and  a  posterior. 

The  buccal  nerve  goes  between  the  pterygoid  muscles, 
giving  some  filaments  to  these,  and  is  then  distributed 
upon  the  buccinator,  forming  a  plexus  upon  this  muscle 
with  the  infra-orbital  and  the  facial.  The  pterygoid  nerve 
consists  of  two  or  three  branches,  which  go  to  the  ptery- 
goid muscles. 

SECTION    V. 

COMPARATIVE   ANATOMY   OF   THE   TEETH. 

The  examination  of  similar  organs  in  the  inferior  ani- 
mals, has  always  been  a  subject  of  deep  interest  and  close 
study  to  the  anatomist  and  physiologist,  and  always  re- 
garded by  them  as  essential  to  the  full  understanding  of 
the  structure  and  functions  of  the  various  organs  of  the 
human  body — to  the  full  development  of  medical  science. 

What  is  true  of  the  body,  as  a  whole,  applies  with  equal 
force  to  its  several  parts.  Each  organ  finds  its  analogue 
in  some  one  or  more  of  the  inferior  animals;  and  the  teeth, 
as  forming  parts,  and  indispensable  parts,  of  the  human 
frame,  come  in  equally  for  their  share  of  examination,  in 
this  comparison  of  organs,  among  the  inferior  animals. 

The  importance  of  this  subject  has  now  fully  aroused 
the  master  spirits  of  the  profession  to  investigation  in  this 


COMPARATIVE  ANATOMY  OP  THE  TEETH.  269 

department  of  scientific  and  practical  research ;  and  their 
labors  have  already  been  crowned  with  the  most  useful 
and  happy  results. 

Cuvier  and  Owen,  with  many  others,  have  shown  that 
the  teeth  of  all  animals  obey  the  same  fixed  and  immutable 
law  of  limitation  in  their  form,  size,  structure,  function, 
and  duration — in  a  word,  that  all  the  essential  elements  of 
their  organization  are  obedient  to,  and  governed  by  the 
same  general  laws.  Still  further,  the  teeth  are  now  re- 
garded as  forming  the  most  secure  basis  for  classifying  the 
animal  kingdom;  for  every  class  of  animals  having  the 
form  of  its  teeth  differing  from  that  of  every  other  class,  we 
readily  recognize  the  distinction,  and  obtain  a  foundation 
of  classification  superior  to  any  other — while  from  the 
great  durability  of  these  organs,  and  their  superior  resist- 
ance to  the  process  of  decomposition,  the  geologist  is  fur- 
nished with  a  key  by  which  he  can  unlock  the  history  of 
the  past,  and  testify,  not  simply  of  the  existence  of  ani- 
mals long  since  extinct,  but  accurately  classify,  and  faith- 
fully describe  their  habits,  food,  and  other  peculiarities. 
To  the  dental  student,  therefore,  an  acquaintance  with 
comparative  dental  anatomy,  as  far  as  his  opportunities 
will  allow,  becomes  a  matter  of  great  interest,  and  should 
always  hold  a  high  rank  among  the  various  studies  per- 
taining to  his  profession. 

We  do  not,  by  any  means,  however,  intend  to  enter  into 
any  lengthy  detail  on  comparative  dental  anatomy;  for 
such  an  attempt  would  be  entirely  incompatible  with  the 
limits  of  the  present  work,  as  well  as  altogether  unneces- 
sary since  the  publications  of  Owen,  Blandin,  and  others. 

All  that  we  propose  here,  is  simply  to  give  such  a  general 
outline  as  may  induce  every  student  to  examine  the  sub- 
ject for  himself,  and  so  to  estimate  the  value  of  such 
knowledge  as  to  be  persuaded  to  devote  all,  or  as  much  of 
his  leisure  moments  as  he  can  spare  to  its  study  and 
investigation. 

The  extent  of  the  dental  organs  proper  seems  to  be  lim- 
ited to  the  vertebrated  division  of  the  animal  kingdom,  or 


270  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

confined  to  those  possessing  a  spine.  In  the  invertebrata, 
instead  of  true  teeth,  the  parts  answering  this  purpose  are 
rather  horny  or  calcareous  indurations. 

The  class  mammalia,  with  but  few  exceptions,  have  teeth ; 
and,  according  to  M.  Geoffrey,  St.  Hilaire,  some  animals 
which  appeared  to  be  entirely  without  them,  were  found  to 
possess  them  during  a  portion  of  their  life. 

Every  tooth  in  the  human  subject  consists  naturally  of 
a  crown,  neck  and  root;  but  this  division  does  not  apply 
to  all  the  mammalia,  for  the  incisors  of  the  rodentia,  and 
the  tusks  of  the  elephant,  are  covered  with  enamel  over 
their  whole  extent,  and  are  hence  said  to  be  without  roots. 
This  distinction  is,  however,  not  considered  good,  since  por- 
tions of  these  teeth  are  imbedded  like  the  roots  of  all  others 
in  alveolar  cavities. 

The  teeth  of  the  mammalia  are  divided  into  "  simple 
compound,  and  semi-compound  or  mixed/5 

Like  the  human  teeth,  the  simple  have  no  "  anfractuosi- 
ties"  on  their  outer  surface.  The  crown  consists  of  a  regu- 
lar shell  of  ivory,  covered  with  a  smooth  and  even  layer  of 
enamel. 

The  compound  teeth,  on  the  other  hand,  look  like  several 
teeth  joined  together,  as  they  have  their  surface  presenting 
such  deep  sinuosities,  and  the  cavity  of  the  compound  tooth 
has  as  many  subdivisions  as  there  are  parts  joined  together. 
"A  good  idea,"  says  M.  Cuvier,  "of  the  compound  teeth  of 
animals  may  be  drawn  from  the  human  molar  teeth,  which 
have  a  simple  crown  and  compound  root,  whilst  the  former 
have  generally  a  simple  root  and  compound  crown.  Sup- 
pose the  roots  of  the  large  human  molars,  covered  with 
enamel  and  joined  together  by  cement,  and  you  have  a  type 
of  the  compound  teeth  of  other  mammalia."  -f*» 

The  teeth  of  the  mammalia  are  also  divided,  like  the 
human  teeth,  into  the  deciduous  or  milk,  and  the  permanent 
teeth.  The  number  of  teeth  in  this  class  varies  very  much, 
though  less  than  in  the  other  vertebrata.  The  highest 
number  is  stated  to  be  190,  and  only  to  be  found  in  the 
dolphin.  The  form  of  the  teeth  constitutes  the  especial 


COMPARATIVE  ANATOMY  OF  THE  TEETH.  271 

mark  of  distinction  among  the  different  mammalia.  They 
are  all  received  into  proper  alveolar  cavities,  supported  by 
and  contained  within  the  maxillary  or  intermaxillary  bones. 
The  teeth  of  mammalia  are  also  distinguished  from  those 
of  man  by  their  varied  conformation,  especially  of  the 
crown,  which  is  asserted  to  differ  as  widely  as  the  food  upon 
which  they  each  respectively  subsist  Those  of  the  carniv- 
erous  and  ferocious  class,  which  feed  on  flesh  for  example, 
have  crowns  with  much  stronger  prominences,  and  more 
pointed  and  cutting  edges,  while  those  on  the  other  hand 
which  live  on  vegetable  food,  and  are  peaceable  in  their 
disposition,  have  flat  and  large  crowns. 

The  human  teeth  come  between  these  two  extremes,  and 
partake  of  the  characters  of  both,  and  hence  it  is  that  man 
is  regarded  as  an  omniverous  animal,  his  teeth  being 
adapted  to  living  on  both  animal  and  vegetable  diet. 

The  teeth  of  the  lower  mammalia  consist,  as  in  man,  of 
ivory  and  enamel,  and  they  are  arranged  in  similar  man- 
ner. The  animals,  however,  have  a  substance  called  cement, 
or,  as  Tenon  terms  it,  the  "osseous  cortical  substance;" 
which,  though  existing  in  human  teeth,  is  by  no  means  so 
abundant  or  extensive. 

The  cement  is  harder  than  the  ivory,  but  not  so  hard  as 
enamel.  It  blackens  sooner,  on  exposure  to  heat,  than  the 
latter,  showing  that  it  contains  a  greater  amount  of  animal 
matter.  It  is  said  to  be  so  abundant  in  the  grinders  of  the 
elephant,  as  to  form  about  half  their  volume.  Its  mode  of 
formation  is  not  settled :  some  think  it  is  the  ossification 
of  the  internal  membrane  of  the  follicle — others,  with  Cu- 
vier,  that  the  same  organ  which  secretes  the  enamel,  after 
it  is  formed,  then  furnishes  the  cement.  The  chemical 
analysis  of  cement  is  given  as  follows : 

Animal  matter,  43.01 

Phosphate  of  lime,  52,94 

Carbonate  of  lime,  4.05 

The  duration  or  period  of  growth  in  the  teeth  of  man  and 
mammalia  varies,  so  much  so  that  in  the  statement  about 


272  COMPARATIVE  ANATOMY  OP  THE  TEETH. 

to  be  made,  the  law  of  fixed  limitation  in  the  growth  of  all 
organs  would  seem  to  have  some  exceptions.  The  rodentia, 
pachydermata,  and  cetacece,  are  cited  as  instances  of  unlim- 
ited growth  of  the  teeth,  and  such  indefinite  growth  as 
is  confined,  almost  in  all  cases,  to  the  incisors  or  ca- 
nines. The  cause  of  this  constant  growth  of  these  teeth 
during  life,  is  thus  given  by  M.  Blandin:  "These  teeth," 
he  says,  "are  classed  with  those  which  have  no  roots;  their 
internal  cavity  is  conical  in  form.  The  pulp,  conical  also, 
rests,  by  a  large  base,  upon  the  bottom  of  the  alveolus, 
whence  it  receives  its  vessels  and  nerves,  and  not  through 
the  medium  of  a  pedicle. 

"In  consequence  of  this  arrangement,  it  is  evident  that 
the  bony  matter  can  never  surround  the  pulp  in  such 
a  manner  as  to  interrupt  its  functions ;  and  there  is  no 
reason,"  he  then  a'dds,  "why  it  should  not  continue  to 
secrete  this  substance  during  life." 

The  order  in  which  the  teeth  of  mammalia  make  their 
appearance,  is  the  same  as  in  man,  i.  e.  from  before  to  the 
back  part  of  the  mouth.  The  number  of  dentitions  in  some 
of  the  mammalia  is  not  limited  as  in  man.  The  elephant, 
it  is  found,  has  its  molars  renewed  as  many  as  eight  times. 

This  frequent  renewal  of  the  teeth,  it  seems,  is  regulated 
in  proportion  to  the  life  of  the  animal,  as  to  whether  long 
or  short,  and  there  are  but  two  ways  in  which  the  animal 
can  be  kept  supplied  with  teeth,  either  to  replace  by  a  new 
set  when  the  present  ones  are  lost,  or  by  constantly  adding 
new  matter  to  the  base  of  those  already  formed,  as  fast  as 
they  are  destroyed  by  friction  on  their  upper  surface.  The 
teeth  are  liable  to  be  ivorn  away  from  friction,  some  more 
than  others,  as  the  back  teeth  of  the  elephant  are  not 
so  much  worn  as  the  front.  The  kind  of  food  seems  to 
exert  a  special  influence  in  this  wearing  away ;  those  that 
live  on  grass  and  nuts,  as  the  gramenivora  and  rodentia,  have 
distinct  lines  on  their  cutting  and  grinding  surfaces,  and 
the  direction  of  these  lines  indicates  the  direction  of  the 
teeth  in  the  mastication  of  the  food.  In  the  ruminantia  the 
lines  are  transverse,  showing  that  the  friction  is  from  side 


COMPARATIVE  ANATOMY  OF  THE  TEETH.  2*73 

to  side,  while  in  the  rodentia  they  are  antero-posterior, 
showing  the  friction  to  be  from  front  to  back. 

In  the  carnivora,  on  the  other  hand,  or  those  that  live  on 
flesh,  there  is  very  little  wearing  away  of  the  teeth,  scarcely 
any  lines  from  friction  to  be  seen,  and  the  points  and  cut- 
ting edges  are  preserved  to  the  end  of  life.  This  ine- 
quality in  the  wearing  of  the  teeth  has  been  turned  to 
practical  account  in  determining  the  age  of  the  horse,  and 
the  incisors  are  those  by  which  the  age  is  known.  "  The 
middle  teeth,  says  M.  Cuvier,  begin  to  appear  about  fifteen 
days  after  birth,  and  at  two  years  and  a  half  the  middle 
ones  are  replaced ;  at  three  and  a  half  the  two  next  follow, 
and  at  four  and  a  half  the  outermost  or  corner  teeth.  All 
these  teeth  with  originally  indented  crowns,  lose  by  degrees 
this  character  by  detrition.  At  seven  and  a  half  or  eight 
years  the  depressions  are  completely  effaced,  and  the  horse 
is  no  longer  marked.  The  inferior  canines  appear  at  three 
years  and  a  half,  the  superior  at  four  years.  They  remain 
pointed  until  the  sixth,  and  at  ten  begin  to  peel  away." 
The  horse  seldom  lives  longer  than  thirty  years. 

With  these  general  remarks,  we  will  now  proceed  to  run 
a  very  brief  contrast  between  the  teeth  of  the  different  or- 
ders of  the  class  mammalia  and  those  of  man,  commencing 

/  o 

with  the  highest  in  the  scale  and  then  descending.  The 
first  order  is  the 

QUADRUMANA. — This  order  is  divided  into  the  monkeys, 
simicB)  and  lemurs.  The  chimpanzee  and  ourang-outang  con- 
stitute the  highest  order  of  monkey,  and  are  next  to  man 
in  their  organization.  According  to  Mr,  Owen,  the  most 
prominent  points  of  distinction  between  the  dentition  of 
man  and  that  of  these  higher  quadrumana,  consist  in  the 
"  absence  of  the  interval  between  the  upper  lateral  incisor 
and  the  canine  in  man,  and  the  comparatively  small  size 
of  the  latter  tooth,"  (Fig,  75.) 

The  human  teeth  are  more  equal  in  size,  and  describe  a 
more  regular  curve  in  both  jaws,  and  do  not,  as  just 
stated,  present  the  vacant  space  of  the  monkey.  The  in- 
cisors of  the  human  teeth  are  smaller  in  proportion  to  the 
18 


274 


COMPARATIVE  ANATOMY  OF  THE  TEETH. 


FIG.  75.     A 


molars  than  those  of  the  chimpanzee  or  orang.  The  upper 
and  lower  bicuspids  are  also  smaller  in  proportion  to  the 
molars,  than  those  of  these  animals. 

In  the  human  teeth 
the  crowns  of  the  true 
molars  are  observed  to 
be  larger  in  proportion 
to  the  bicuspids,  still 
larger  in  proportion  to 
the  canines  and  incisors, 
and  larger  in  proportion 
to  the  jaws,  and  have 
the  borders  of  their 
grinding  surface  more 
round  than  is  found  in 
the  chimpanzee  and 
orang.  When  the  per- 
manent teeth  appear,  it 
is  remarked  that  the 
first  true  molar  in  both 
upper  and  lower  jaw  is 
"  much  more  worn,"  in 
comparison  with  the  other  molars,  than  in  the  chimpan- 
zee and  orang,  in  consequence  of  the  longer  time  which 
elapses  between  the  appearance  of  the  first  and  last  true 
molars  of  the  human  teeth  and  those  of  these  animals, 
and  consequently  the  greater  amount  of  friction  the  first 
molars  are  subject  to. 

The  number  of  teeth  in  these  quadrumana  is  the  same 
as  in  man.  The  deciduous  set  are  the  same  in  number. 
The  following  contrast  between  the  human  deciduous  teeth 
and  those  of  the  chimpanzee  and  orang,  is  from  the  pen  of 
Mr.  Owen. 

"The  upper  milk  incisors  of  the  chimpanzee,"  he  says, 
"are  relatively  larger  than  in  man,  especially  the  middle 
pair,  but  the  disproportionate  size  of  these  is  still  more  man- 

FIG.  75,  A  represents  the  superior  dental  arch  of  man. 

FIG.  75,  B  represents  the  superior  dental  arch  of  a  chimpanzee. 


COMPARATIVE  ANATOMY  OF  THE  TEETH.  275 

ifest  and  characteristic  of  the  orang,  and  the  outer  angle  of 
the  lateral  incisors  is  more  rounded  off  in  this  quadruman. 
The  crown  of  the  canine  is  longer  and  more  pointed  in  the 
chimpanzee  than  in  man;  still  more  so,  and  farther  apart 
from  the  incisor,  in  the  orang.  The  first  molar  is  as  large 
in  the  human  subject  as  in  the  chimpanzee,  and  its  crown  is 
divided  into  two  principal  cusps,  hut  the  outer  and  larger 
one  has  a  small  subdivision  notched  off  posteriorly,  and  the 
inner  cusp  is  relatively  larger  than  in  the  chimpanzee.  The 
first  upper  molar  of  the  orang  is  simply  bicuspid,  but  is 
larger  than  in  the  chimpanzee.  The  second  molar  of  the 
human  child  could  scarcely  be  distinguished  from  that  of 
the  young  chimpanzee,  both  are  quadricuspid,  and  the  same 
oblique  ridge  crosses  the  grinding  surface  from  the  ante- 
ro-internal,  to  the  postero-external  tubercle,  but  the  pointed 
summits  of  the  two  outer  cusps  are  a  little  more  extended 
in  the  chimpanzee.  The  second  molar  of  the  orang,  besides 
its  larger  size,  has  the  four  tubercles  better  defined,  and  the 
oblique  ridge  less  developed. 

"  The  lower  deciduous  incisors  of  the  anthropoid  apes 
differ  from  those  of  the  human  subject  in  their  superior 
size,  greater  relative  thickness,  and  the  lateral  incisor  more 
particularly,  by  the  rounding  off  of  the  auter  angle. 

"The  lower  canine  of  the  chimpanzee  has  a  larger, 
longer,  and  more  pointed  crown,  with  a  sharp  posterior 
edge;  this  is  less  marked  in  the  canine  of  the  orang,  which 
is  larger  arid  thicker  than  in  the  chimpanzee;  the  crowns 
of  the  upper  and  lower  canines  are  more  obliquely  opposed, 
the  lower  one  being  more  advanced  in  those  apes  than  in  the 
human  subject. 

"  The  first  lower  deciduous  molar  of  the  human  subject 
has  four  tubercles  and  a  small  anterior  ridge,  and  is  larger 
than  that  of  the  chimpanzee,  which  supports  a  single  large 
pointed  cusp  and  a  posterior  ridge.  The  first  molar  of  the 
orang  has  a  similar  simple  crown,  but  is  as  large  as  that 
of  the  child.  The  second  molar  is  of  equal  or  superior  size 
in  the  human  subject  to  that  in  the  chimpanzee,  but  it 
supports  three  outer  and  two  inner  cusps,  while  in  the 


276  COMPARATIVE  ANATOMY   OF   THE  TEETH. 

chimpanzee  it  has  but  four  cusps;  in  the  orang,  the  fifth 
external  and  posterior  tubercle  is  feebly  indicated.  The 
deciduous  molars  of  the  human  subject,  as  in  the  chim- 
panzee and  orang,  have  each  three  fangs  in  the  upper  and 
two  in  the  lower  jaw." 

In  the  order  of  succession  in  the  teeth  of  these  quadru- 
mana  and  man,  there  is  some  difference.  It  has  already 
been  stated,  in  the  description  of  human  dentition,  that 
the  first  true  molar  and  first  incisor  are  the  earliest  to 
appear  in  the  permanent  set;  and  between  these  two 
points,  Mr.  Hunter  remarks,  the  teeth  progress  more  rap- 
idly than  those  behind. 

But  in  the  quadrumana  this  is  not  the  case,  and  the 
progress  is  slower ;  for  in  these  the  second  molar  is  found 
to  precede  the  bicuspid,  and  the  last  molar  the  canine. 
And  the  cause  of  this  difference  is  assigned  to  the  difference 
in  the  food.  Monkeys,  living  on  fruits  and  meats,  require 
the  use  of  their  grinders  at  an  earlier  period  than  either 
the  canine  or  incisors.  In  the  baboons  and  mandrills ,  which 
are  a  step  lower  than  the  monkey  tribe,  we  find  their  denti- 
tion most  especially  distinguished  from  the  human,  by  the 
canine  teeth  presenting  the  ferocity  and  strength  of  the 
carnivorous  animals.  Those  of  the  mandrill  are  described 
as  "  weapons  most  formidable  for  their  size  and  shape,"  the 
upper  canines  especially,  which  pass  behind  the  crowns  of 
the  lower  incisors,  and  on  the  outside  of  the  first  lower 
bicuspid,  which  seems  pressed  back,  as  it  were,  by  the  ac- 
tion of  the  upper  canines.  A  considerable  space  divides 
the  upper  canine  from  the  incisors — a  shorter  one  separates 
it  from  the  bicuspid.  The  first  bicuspid  of  the  lower  jaw 
is  distinguished  by  the  base  of  its  crown  having  an  unusual 
anterior  prolongation,  which  is  reduced  to  a  cutting  edge 
by  the  friction  of  the  upper  canine. 

The  class  of  lemurs  are  the  lowest  in  the  scale  of  the 
quadrumana,  and  differ  from  these  in  their  dentition,  as 
well  as  from  the  human  race,  by  having  thirty-six  teeth 
instead  of  thirty-two ;  the  difference  being  in  the  bicuspids, 
of  which  these  animals  have  six  to  each  jaw,,  three  on 


COMPARATIVE  ANATOMY  OF  THE   TEETH.  27 T 

either  side  instead  of  four,  as  in  man  and  the  higher 
monkey. 

The  two  incisors  of  the  upper  jaw  are  separated  by  a 
wide  space  from  the  two  on  the  left,  and  are  small,  vertical, 
and  have  their  crowns  short  and  expanded. 

The  canine  is  long,  compressed,  and  curved,  with  its 
edge  sharp  and  pointed.  The  three  bicuspids  present,  on 
the  inner  side  of  their  crowns,  a  tubercle,  while  on  their 
outer  there  is  extended  a  compressed  and  pointed  lobe. 

Both  jaws  have  their  first  true  molars  the  largest.  The 
first  bicuspid,  in  the  upper  jaw,  has  its  two  roots  connate 
or  joined  together;  those  of  the  other  two  are  distinct. 
The  roots  of  the  upper  molars,  as  in  the  human  teeth,  are 
three  in  number  ;  but  in  the  lower  jaw,  both  bicuspids  and 
molars  have  only  two  roots.  The  number  of  deciduous 
teeth  in  the  lemurs  is  twenty-four,  instead  of  twenty,  as  in 
man — the  excess  being  in  the  molars.  Among  the  quad- 
rumana  there  are  two  genera  described,  which  are  most 
remarkable  for  their  very  singular  and  anomalous  denti- 
tion. They  consist  of  the  goleopitliecus  (the  weasel-like 
monkey)  and  the  cheiromys. 

The  former  are  said  to  resemble  the  bat,  in  having  a 
kind  of  wing,  formed  of  a  fold  of  the  integument,,  reaching 
from  the  front  to  the  hind  extremity,  and  may  be  called 
flying  monkeys. 

The  teeth  in  this  genus  are  thirty-four  in  number,  i.  e. 
four  incisors  in  the  upper  jaw,  two  on  either  side,  and  six 
in  the  lower  jaw,  three  on  either  side,  making  ten  incisors 
in  all — two  more  than  in  man.  The  two  anterior  upper 
incisors  have  a  wide  space  between  them,  are  very  small, 
and  have  their  crowns  expanded  and  presenting  three  or 
four  tubercles.  The  second  incisor  of  the  upper  jaw,  which 
is  said  to  be  connected  with  the  intermaxillary  bone,  has 
one  very  striking  peculiarity  in  having  two  roots.  Its 
crown  is  of  a  triangular  shape,  having,  at  the  front  and 
posterior  base,  a  small  talon — also  dentations,  two  anterior 
and  three  posterior,  at  the  same  points. 

The  upper  canine  has,  very  unlike  the  human,  two  roots. 


2*78  COMPARATIVE   ANATOMY   OF   THE   TEETH. 

The  first  upper  biscupid  has  its  crown  of  a  trihedral  shape. 
The  second  bicuspid  has  a  pointed  talon  at  its  base. 

The  crowns  of  the  first  two  incisors  of  the  lower  jaw  pre- 
sent a  very  peculiar  arrangement  in  the  form  of  a  comb. 
This  tooth-like  or  pectinated  appearance,  is  compared  to  the 
little  notches  on  the  edge  of  aa  new-formed  hunian  incisor," 
though  the  serrations  are  much  deeper  and  more  numer- 
ous. These  teeth  have  a  single  root.  The  third  incisor  is 
thought  to  resemble  a  canine,  though  its  crown  is  described 
as  being  broad,  horizontal,  and  having  four  shallow  notches 
on  its  margin ;  this  tooth,  also,  has  a  single  root.  The 
lower  canine,  like  the  upper,  has  two  roots.  The  milk 
teeth  are  twenty-two  in  number — ten  to  the  upper  jaw, 
and  twelve  to  the  lower. 

In  the  cheiromys  a  resemblance  is  traced  to  the  rodentia, 
in  the  chisel-like  incisors  of  both  jaws,  which  make  but  a 
single  pair,  and  are  large  and  curved.  The  canines  are 
wanting,  and  a  wide  space  separates  the  incisors  from  the 
molars. 

As  the  cutting  edge  of  the  teeth  below  does  not  strike 
against  the  "posterior  ridge"  of  those  above,  M.  Blainville 
supposes  that  the  chisel  teeth  of  the  incisors  have  a  differ- 
ent use  from  those  of  the  rodents,  and  that  the  cheiromys 
employ  them  as  "cutting  pincers  to  remove  the  bark  of 
trees,  in  search  of  larvae  or  insects,"  though  the  flat,  smooth 
crowns  of  the  molars  would  seem  to  show  their  food  not  to 
be  entirely  of  this  character.  The  upper  jaw  has  four  mo- 
lars on  each  side,  and  the  lower  three,  placed  vertically 
and  parallel.  The  first  upper  molar  is  the  smallest,  and 
the  second  the  largest  of  that  jaw.  In  the  lower  jaw 
the  last  molar  is  the  smallest.  A  striking  contrast  with 
the  human  molar  exists  in  the  roots.  In  the  cheiromys 
the  first  and  last  molars  of  the  upper  jaw  have  but  one 
root ;  the  two  middle  have  each  three  roots.  In  the  lower 
jaw  the  first  molar  has  two  roots,  the  other  two  but  one. 

INSECTIVORA. — This  order  is  regarded  as  the  transition 
step  between  the  quadrumana  and  carnivora.  The  differ- 
ent genera  are  remarkable  for  the  varieties  in  their  teeth, 


COMPAKATIVE  ANATOMY   OF  THE  TEETH.  2*79 

in  number,  shape,  and  size.  The  most  common  character- 
istic found  to  prevail  is  the  presence  of  "several  sharp 
points  upon  the  crowns  of  the  true  molar  teeth." 

This  order  is  divided  into  the  families  of  moles  (talpidee), 
shrews  (solicidge),  and  hedge-hogs  (erinacidas.) 

The  mole  of  the  cape,  as  it  is  called,  according  to  Mr. 
Owen,  has  forty  teeth.  Its  dental  formula  is  to  the  up- 
per jaw  on  either  side,  three  incisors,  one  bicuspid,  and  six 
molars ;  to  the  lower  jaw,  three  incisors,  two  bicuspids,  and 
five  molars.  The  American  mole  has  thirty-six  teeth:  to 
the  upper  jaw,  on  either  side,  three  incisors,  one  canine, 
three  bicuspids,  three  molars;  to  the  lower  jaw_,  two  inci- 
sors, no  canine,  three  bicuspids,  three  molars.  The  common 
mole  has  forty-four  teeth,  in  the  arrangement  of  which 
there  is  some  difference  among  naturalists.  M.  Cuvier 
rates  no  canine  to  the  lower  jaw,  and  gives  four  bicuspids 
and  three  molars  on  either  side  to  both  jaws.  Mr.  Bell 
allows  two  canine  to  the  lower  jaw,  gives  no  bicuspids,  and 
makes  seven  molars  to  the  upper,  and  six  to  the  lower  jaw, 
on  either  side;  while  M.  Blainville  has,  to  both  upper  and 
lower  jaw,  on  each  side,  four  incisors,  one  canine,  three 
bicuspids,  three  molars. 

In  the  hedge-hog,  one  variety  has  thirty-six  teeth.  The 
formula  given  is,  incisors  two,  canine  one,  bicuspids  three, 
molars  three,  to  both  upper  and  lower  jaw,  on  either  side. 
The  common  hedge-hog  has  the  same  number,  but  differ- 
ently arranged  as  follows:  incisors  three,  bicuspids  four, 
molars  three,  on  either  side,  in  each  jaw.  Another  variety 
has  forty-eight,  i.  e.  incisors  three,  canine  one,  bicuspids 
four,  molars  four,  on  either  side,  in  each  jaw. 

CHEIROPTERA. — This  order  includes  two  divisions  of  the 
bats — first,  those  that  live  on  insects,  and  second,  those 
that  live  on  fruits. 

The  number  of  teeth  belonging  to  the  first  is  thirty- 
eight,  i.  e.  incisors  two,  canine  one,  bicuspids  three,  molars 
three,  to  the  upper  jaw,  on  either  side ;  and  to  the  lower, 
incisors  three,  canine  one,  bicuspids  three,  molars  three. 

The  vampire  or  blood-sucking  bat  has  but  twenty  teeth. 


280 


COMPARATIVE   ANATOMY -OF   THE   TEETH. 


The  dental  formula  is,  incisors  one,  canine  one,  bicuspids 
two,  to  the  upper  jaw,  on  either  side ;  and  to  the  lower, 
incisors  two,,  canine  one,  bicuspids  three.  The  bats  which 
live  on  fruit  have  thirty-four  teeth.  Their  dental  formula 
is,  to  the  upper  jaw,  on  either  side,  incisors  two,  canine 
one,  bicuspids  two,  molars  three;  in  the  lower,  incisors 
two,  canine  one,  bicuspids  three,  molars  three. 

CARNTVORA. — Animals  of  this  order  live  entirely  on  one 
kind  of  food,  i.  e.  flesh;  and  their  dental  system  being  de- 
signed not  only  to  masticate,  but  also  to  obtain,  seize,  and 
kill  their  prej,  their  teeth  are  much  more  extensive  than 
in  man. 

The  different  genera  present  variations  from  the  regular 
type  as  established  in  the  feline  or  cat  tribe. 

FIG.  76. 


Among  the  whole  order  there  are  found  to  be  six  in- 
cisors in  each  jaw,  with  few  exceptions.  The  canines  are 
never  absent,  are  largely  developed,  and  have  long,  eoni- 

FIG.  76  represents  the  deciduous  and  permanent  teeth  of  the  dog.  2  3  4  d 
Deciduous  molars  of  the  upper  and  lower  jaw.  2  3  4  p  Permanent  molars. 
d  c  Deciduous  canine  of  both  jaws,  d  i  Deciduous  incisors  of  both  jaws, 
i  Permanent  incisors.  2  m  3  m  Tubercular  molars. 


COMPARATIVE   ANATOMY   OF   THE  TEETH. 


281 


cal,  sharp-pointed   and   cutting   crowns.     The  variations 
from  the  type  are  found  in  the  molars. 

We  will  give  a  few  examples  in  illustration.  The  cat, 
taken  as  the  type  of  the  order,  has  28  teeth — the  upper 
jaw  having,  on  either  side,  incisors  3,  canine  1,  hicuspids 
3,  molar  1.  In  the  lower  jaw  there  are,  incisors  3,  canine 
1,  hicuspids  2,  molar  1. 

In  the  upper  jaw  the  first  bicuspid  has  a  single  root, 
with  one  exception.  The  second  bicuspid  has  two  strong 
diverging  roots;  the  third  has  three.  In  the  lower  jaw  the 
first  bicuspid  has  two  roots.  The  number  of  milk  teeth  in 
the  cat  is  26.  The  upper  jaw  has,  incisors  3,  canine  1, 
molars  3,  on  either  side.  In  the  lower  jaw  there  are,  in- 
cisors 3,  canine  1,  molars  2. 

The  dog  has  42  teeth.  (Fig.  76.)  In  the  upper  jaw  there 
are  on  either  side,  incisors  3,  canine  1,  bicuspids  4,  mo- 
lars 2.  In  the  lower  jaw  there  is  an  additional  molar. 

There  is  a  FIG.  77. 

single  root  to 
the  incisors, 
canines,  and 
first.bicuspids 
of  both  jaws, 
all  the  rest 
in  the  lower 
jaw  have  two, 
except  the  sec- 
ond bicuspid, 
which  is  con- 
nate. The  sec- 
ond upper  bi- 
cuspid, which 
is  also  called 

sectorial,  has  three  roots,  the  first  true  molar  has  four,  the 
last  three  roots. 

FIG.  77  represents  the  deciduous  and  permanent  teeth  of  the  bear.  1  2  3  4 1) 
Deciduous  molars  of  the  upper  and  lower  jaw.  p  Permanent  molars,  d  i 
Deciduous  incisors,  c  Canine  teeth. 


282  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

The  hyena  has  34  teeth.  In  the  upper  jaw  on  either 
side  there  are,  incisors  3,  canine  1,  bicuspids  4,  molar  1. 
In  the  lower  jaw  there  is  one  bicuspid  less.  The  number 
of  deciduous  teeth  is  28,  i.  e.  incisors  3,  canine  1,  molars 
3,  to  each  jaw  on  either  side. 

The  weasel  has  34,  the  otter  36,  the  badger  30,  the  raccoon 
40,  the  bear  42.  (Fig.  77.)  The  deciduous  teeth  of  the  bear 
are  22,  and  the  seal  has  34  teeth. 

MARSUPIALIA. — This  order,  so  called  from  having  a  pouch 
for  the  accommodation  of  their  young,  are  divided  into  the 
carnivorous  and  herbivorous  genera. 

The  opossum  and  kangaroo  are  familiar  examples  under 
this  head.  The  dog-headed  opossum  (thylacinus)  has  forty- 
six  teeth.  In  the  upper  jaw,  on  either  side,  there  are — 
incisors  four,  canine  one,  bicuspids  three,  molars  four;  in 
the  lower  jaw  are  found — incisors  three,  canine  one,  bicus- 
pids three,  molars  four.  In  other  varieties  of  the  opossum 
the  teeth  vary  in  number,  being  42,  48,  50  and  54.  The 
kangaroo  has  twenty-eight  teeth.  The  canines  are  absent. 
The  animals  of  this  genus  live  on  herbs. 

The  dental  formula  is,  to  the  upper  jaw,  on  either  side, 
incisors  three,  bicuspids  one,  molars  four ;  in  the  lower  jaw, 
there  are,  molars  four,  incisor  one,  bicuspid  one.  Other 
varieties  have  only  twenty-four  teeth. 

KODENTIA. — This  order  includes  the  squirrel,  rabbit,  rat, 
beaver,  &c. 

The  incisors  form  the  distinguishing  characteristic  of 
this  order.  There  is  one  on  either  side,  separated  from 
the  short  series  of  molars  by  a  wide  space.  The  upper 
ones  describe  a  large  segment  of  a  small  circle,  and  are 
regularly  curved ;  the  lower  ones  are  a  smaller  segment  of 
a  larger  circle. 

These  teeth  are  called  " scalpriform"  or  chisel-like.  The 
molar  teeth  are  described  as  presenting  numerous  varieties, 
representing,  in  fact,  all  the  modifications  found  in  the  om- 
nivorous and  herbivorous  genera  of  mammalia.  In  some 
of  the  rodents,  as  the  Chili  rats,  the  molar  teeth  have  no 
roots.  In  others,  as  the  beaver,  they  have  short  roots. 


COMPARATIVE   ANATOMY  OF  THE   TEETH.  283 

The  mode  in  which  the  teeth  are  implanted  in  the  jaws 
varies  according  to  the  diet.  Those,  for  example,  like  the 
true  rat,  which  live  on  a  mixed  food,  do  not  require  so 
great  a  depth  of  the  crown,  and  the  teeth  are  hence  not  so 
firmly  fixed,  nor  so  large  as  in  those  rodents  whose  food  is 
entirely  vegetable,  and  where  the  friction  is  greater. 

The  highest  numher  of  teeth  in  this  order  is  stated  at 
twenty-eight.  The  rahbit  has  six  molars  on  each  side,  in 
the  upper  jaw,  and  five  in  the  lower.  The  squirrel  has 
five  molars  in  the  upper  on  either  side,  and  four  in  the 
lower.  The  rat  has  three  molars  on  each  side,  in  both 
jaws,  though  the  spring-rat,  as  it  is  called,  has  four  molars 
in  both  jaws,  on  each  side. 

EDENTATA. — It  would  be  supposed  from  the  name  of  this 
order  that  all  the  genera  composing  it  were  without  teeth. 
Hence  Mr.  Owen  very  justly  remarks,  it  is  to  be  regretted 
that  such  a  term  should  have  been  applied,  seeing  that  all 
the  species  of  this  order,  except  two,  have  teeth,  though 
nearly  all  are  without  incisors. 

The  ant-eater,  armadillo,  and  sloth,  are  examples  under 
this  head. 

The  ant-eater  has  twenty-six  teeth — seven  on  each  side 
of  the  upper  jaw,  and  six  on  each  side  of  the  lower.  The 
number  in  the  armadillo  is  stated  to  vary  from  twenty-four 
to  twenty-six  on  each  side  of  the  upper  jaw,  and  twenty- 
two  to  twenty-four  in  the  lower ;  making,  in  the  whole, 
from  ninety-four  to  one  hundred  teeth.  The  sloth  has 
eighteen  teeth,  all  molars — there  being  five  on  each  side 
of  the  upper  jaw,  and  four  on  each  side  of  the  lower. 

The  extinct  gigantic  animals  by  the  name  of  megather- 
oids,  some  of  whose  teeth  are  nearly  a  foot  in  length, 
belong  also  to  this  order. 

PACHYDERMATA. — This  order  includes  the  elephant,  mas- 
todon, hippopotamus,  rhinoceros,  hog,  horse,  &c. 

The  elephant,  distinguished  by  its  two  enormous  tusks, 
has  28  teeth.  In  the  upper  jaw,  on  each  side,  there  are  two 
incisors  and  six  molars.  In  the  lower  there  are  only  six 
molars  on  either  side.  The  tusks  are  situated  in  the  inter- 


284  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

maxillary  bones,  and  are  preceded  by  deciduous  ones. 
These  latter  appear  between  the  5th  and  2*7 th  month;  are 
about  two  inches  in  length,  one  third  of  an  inch  in  diame- 
ter, and  are  shed  between  the  first  and  second  year.  In 
about  a  month  or  two  after  this  period,  the  permanent 
tusks  are  described  as  cutting  the  gum,  and  are  then  about 
an  inch  in  length. 

At  birth  the  alveolus  of  the  permanent  tusk  is  a  round 
cell  placed  at  the  posterior  and  inner  part  of  the  temporary 
alveolus.  The  tusks  are  called  the  incisor  teeth  of  the  ele- 
phant, and  are  considered,  in  proportion  to  the  body,  the 
largest  of  all  the  teeth.  They  are  stated  to  have  measured 
nine  feet  in  length,  having  a  base  of  eight  inches,  and 
weighing  150  pounds.  This  is  an  unusual  weight,  the 
more  common  being  from  fifty  to  seventy  pounds. 

In  some  varieties  the  tusks  are  straight,  and  point 
downwards,  and  in  others  of  a  still  more  anomalous  kind, 
one  tusk  has  been  seen  horizontal,  and  the  other  vertical. 
The  molar  teeth  are  of  immense  size  and  complex  structure. 
The  crown  is  mostly  hid  in  the  socket,  only  a  small  portion 
appearing  above  the  gum.  It  is  divided  into  several  per- 
pendicular transverse  plates — coated  with  enamel,  and  then 
covered  with  cement — which  unites  the  several  divisions 
of  the  crown;  these  divisions  come  together  at  the  base 
and  form  the  body  of  the  crown  from  whence  the  roots 
proceed. 

In  the  development  of  the  grinders,  the  summits  of  the 
anterior  plates  begin  to  be  formed  first,  and  then  the  others 
in  succession,  the  anterior  being  in  use  before  the  posterior 
are  formed.  The  first  molar  is  stated  to  have  four  of 
these  vertical  plates  or  divisions  of  the  crown,,  and  two 
roots.  The  second  molar  has  eight  or  nine  plates,  and  also 
two  roots.  The  third  molar  has  from  eleven  to  thirteen 
plates,  and  has  a  small  anterior  and  large  posterior  root. 
It  is  thought  these  three  may  probably  be  deciduous  teeth. 

The  fourth  molar  has  from  fifteen  to  sixteen  plates  in  the 
crown  and  three  roots.  The  fifth  molar  has  from  seventeen 
to  twenty  plates,  appears  above  the  gum  about  the  twentieth 


COMPARATIVE  ANATOMY  OF  THE  TEETH.  285 

year,  and  is  found  not  to  be  shed  before  the  sixtieth.  The 
sixth  and  last  molar  has  from  twenty-two  to  twenty-seven 
plates.  Its  antero-posterior  length  in  the  line  of  the  curv- 
ature is  found  to  measure  from  twelve  to  fifteen  inches, 
and  breadth  about  three  and  a  half  inches. 

The  mastodon  is  an  extinct  race.  It  has  the  tusks  of  the 
elephant,  and  differs  in  its  grinders,  having  their  surfaces 
divided  into  "  wedge-shaped  transverse  ridges,"  instead  of 
the  numerous  vertical  plates  of  the  elephant. 

The  dental  formula  is  given  as  twenty-eight ;  seven  teeth 
on  each  side  to  the  upper  jaw,  and  the  same  number  to  the 
lower.  This  number,  however,  combines  both  the  decidu- 
ous and  permanent  set. 

The  hippopotamus.  This  monster  of  the  waters  is  exceed- 
ingly interesting  to  the  dentist,  as  from  its  teeth,  informer 
times,  were  mostly  supplied  the  best  artificial  substitutes 
for  the  human.  It  was  most  appropriate  for  this  purpose, 
as  the  dentine  was  extremely  hard,  and  sections  of  it  sus- 
ceptible of  very  high  polish.  The  number  of  teeth,  as 
given  by  M.  Cuvier,  is  thirty-two,  i.  e.  six  molars  on  each 
side  of  each  jaw,  two  incisors  on  each  side  of  each  jaw,  and 
two  canines  also  on  each  side  of  each  jaw.  The  three  ante- 
rior molars  (the  premolars  of  Mr.  Owen)  are  conical;  the 
posterior  present  two  pairs  of  points.  The  upper  incisors 
are  short,  conical  and  recurved,  the  inferior  "prolonged, 
cylindrical,  pointed,  and  horizontally  projecting."  The 
upper  canine  is  straight,  the  lower  very  large  and  bent 
back,  recurved. 

Rhinoceros.  This  genus  has  no  canine  teeth.  Its  in- 
cisors vary,  though  the  usual  number  given  is  eight,  two 
on  each  side  of  both  upper  and  lower  jaw.  The  number 
of  molars  is  twenty-eight.  This  animal  is  remarkable  for 
its  single  horn,  though  in  some  varieties  there  are  two. 
The  African  rhinoceros  is  said  to  have  two  horns,  and  no 
incisors. 

The  hog,  (suidce.)  This  family,  among  the  ungulata, 
comprises  the  greatest  varieties  in  dentition.  The  ca- 
nines form  the  most  prominent  feature  of  this  group, 


286 


COMPARATIVE  ANATOMY   OF  THE  TEETH. 


being  remarkable  for  their  "  extraordinary  size,  shape,  and 
direction."     This  is  best  illustrated  in  the  wild  boar,  where 

FIG.  78.     A 


they  curve  forwards,  outwards  and  upwards.  The  molars 
are  regarded  as  complex  in  structure  as  those  of  the  ele- 
phant, while  the  incisors  vary  in  number  in  the  several 
genera.  The  usual  number  of  teeth  is  set  down  at  forty- 
four.  To  both  jaws  on  either  side  there  are,  incisors  3, 

FIG.  78,  A  represents  the  Permanent  Teeth  of  the  Hog.  lnt,2m,  3m,  1st,  2d 
and  3d  Molars.  lp,  2p,  3/>,  4p,  1st,  2d,  3d  and  4th  Premolars.  li,  2i,  3i,  1st, 
2d  and  3d,  Incisors,  c  Canine  teeth. 

FIG.  78,  B  represents  the  Deciduous  and  Permanent  Teeth  of  the  Hog.  The 
figures  and  letters  point  so  distinctly  to  the  different  kinds  of  teeth,  as  to  require 
no  further  explanation. 


COMPARATIVE  ANATOMY  OF  THE  TEETH. 


287 


canine  1,  bicuspids  4,  molars  3,  The  number  of  milk 
teetli  is  made  twenty-eight.  Incisors  3,  canine  1,  molars 
3,  to  both  jaws  on  either  side, 

In  the  Peccari  the  dental  formula  numbers  thirty-eight 
teeth — i.  e.  in  the  upper  jaw,  on  each  side,  there  are,  inci- 
sors two,  canine  one,  bicuspids  three,  molars  three;  in  the 
lower,  on  each  side,  are,  incisors  three,  canine  one,  bicus- 
pids three,  molars  three. 

The  Horse,  (equidce)     This  noble  and  useful  animal,  be- 
longing to  the  family  solidungula,  or  singlQ-hoofed  variety, 
has  forty  teeth.     In  both  jaws,  on  each          pIGi  79> 
side,  there  are  three  incisors,  one  canine, 
three  bicuspids,  and  three  molars. 

The  lower  canines,  according  to  M.  Cu~ 
vier,  are  only  sometimes  present  in  the 
male,  and  always  wanting  in  the  female. 
Between  the  canines  and  first  bicuspids 
there  is  a  wide  space  corresponding  to  the 
angle  of  the  mouth,  where  the  bit  is  re- 
ceived. The  incisors  are  slightly  curved, 
having  long,  subtrahedral  fangs,  taper- 
ing to  their  extremity,  and  closely  ar- 
ranged in  the  segment  of  a  circle.  These 
teeth,  says  Mr.  Owen,  are  distinguished 
from  those  of  all  other  animals  "by  the 
fold  of  enamel  which  penetrates  the  body 
of  the  crown  from  its  broad,  flat  summit,  like  the  inverted 
finger  of  a  glove."  This  fold  encloses  a  cavity,  which  pre- 
sents the  form  of  an  island,  when  the  tooth  begins  to  be 
worn.  This  cavity  is  partly  filled  by  "cement,  and  partly 
by  the  discolored  substances  of  the  food,  and  is  called  the 
mark."  It  is  described  as  being  usually  obliterated,  in  the 
middle  incisors,  about  the  sixth  year — in  the  second  inci- 
sors, about  the  seventh;  and  the  third,  about  the  eighth, 

FIQ.  79,  A  longitudinal  section  of  the  Incisor  of  a  Horse,  e  Enamel. 
d  Dentine,  c  Cement.  c  Cement  reflected  into  the  depression  of  the 
crown,  s  Colored  tartar  and  food  filling  up  this  cavity  and  constituting  what 
is  known  as  the  "  mark"  and  made  use  of  to  tell  the  age  of  the  horse. 


288  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

in  the  lower  jaw.     It  is  longer  disappearing  in  those  of  the 
upper  jaw. 

EUMINANTIA. — This  order  is  considered  to  be  the  best 
determined  in  the  whole  class  of  mammalia. 

The  camel,  lama,  dromedary,  ox,  sheep,  goat,  stag,  &c., 
are  varieties  of  this  order. 

The  genera  are  divided  into  those  which  are  without 
horns,  and  those  which  have  them.  The  latter  class  is  by 
far  the  most  numerous.  The  camel  and  lama  are  examples 
of  the  former,  while  the  ox,  ram,  stag,  &c.,  are  specimens' 
of  the  latter.  Another  division  is  into  those  in  which  the 
horns  are  solid,  and  those  in  which  they  are  hollow. 

In  the  development  of  the  horns  arid  teeth,  the  relation 
seems  to  be  inverse,  for  where  the  horns  are  present,  we 
find  the  canines  absent,  and  where  the  horns  are  wanting, 
as  in  the  musk,  canines  are  not  only  seen,  but  also  a  pair 
of  incisors  in  the  upper  jaw. 

The  diiferent  genera  are  called  ruminantia,  from  the  pe- 
culiar faculty  they  possess  of  masticating  their  food  a 
second  time,  by  returning  it  to  the  mouth  after  first  swal- 
lowing it. 

This  singular  faculty  depends  on  the  structure  of  the 
stomach,  or  rather  stomachs,  which  are  four  in  number ; 
and  the  first  three  are  so  related  to  each  other  that  the 
food  may  enter  either  of  them,  as  the  ossophagus  ends  at 
their  common  point  of  communication. 

The  first  stomach  is  called  the  paunch,  and  receives  the 
vegetable  matters  from  the  first  mastication.  This  passes 
into  the  second,  which  is  of  honey-comb  formation,  and  here 
the  food  is  moistened  and  compressed  into  little  pellets 
called  cud,  which  is  now  returned  into  the  mouth  to  un- 
dergo a  second  mastication.  It  is  now  passed  from  the 
mouth  into  the  third  stomach,  which  is  laminated  in  its 
appearance,  and  from  this  it  enters  into  the  fourth,  which 
has  the  rugce,  and  which  is  the  seat  of  digestion  proper. 

One  characteristic  in  the  teeth  of  this  order  is,  the  ab- 
sence of  incisors  and  canines  in  the  upper  jaw.  This  is 
furnished  by  a  callous  pad  as  a  substitute.  A  second  char- 


COMPARATIVE  ANATOMY  OP  THE  TEETH.  289 

acter  is  the  constancy  of  eight  incisors  in  the  lower  jaw, 
the  two  outer  of  which  Mr.  Owen  calls  canine.  The  usual 
dental  formula  gives  32  teeth  to  the  ruminantia:  6  bi- 
cuspids and  6  molars  to  the  upper  jaw;  to  the  lower,  6 
incisors,  2  canines,  6  bicuspids,  and  6  molars.  A  wide 
space  separates  the  incisors  and  bicuspids. 

The  upper  bicuspids  have  three  roots;  the  upper  true 
molars  have  four  roots.  In  the  lower  jaw  both  bicuspids 
and  molars  have  but  two  roots;  but  the  second  root  in  the 
last  molar  consists  of  two  connate  roots. 

CETACEA. — This  order  of  mammalia  includes  the  whales, 
which  have  no  teeth,*  properly  speaking,  but  horny  sub- 
stitutes, called  "whale-bone"  or  "baleen."  The  so-called 
teeth  of  the  right  whale  are  in  the  form  of  plates,  termin- 
ating in  a  fringe  of  bristles.  In  a  new-born  whale  Mr. 
Owen  found  the  number  of  these  plates  to  be  190.  The 
largest  are  arranged  on  each  side  of  the  upper  jaw  in  a 
longitudinal  series  and  close  to  each  other,  vertically,  with 
their  flat  surfaces  looking  forwards  and  backwards,  and 
their  free  margins  outwards  and  inwards.  The  smaller 
plates  are  disposed  in  an  oblique  series  within  the  larger. 
The  base  of  each  plate  is  described  as  being  fixed  upon  a 
pulp  developed  within  a  broad,  shallow  depression  of  the 
gunr,  and  covering  the  entire  surface  of  the  maxillary  and 
anterior  portion  of  the  palate  bones — the  whale  thus  hav- 
ing palatal  teeth.  The  base  of  each  plate  is  hollow,  for 
receiving  the  pulp — bearing  the  same  relation  to  it  that 
the  pulp  of  a  true  tooth  does  to  its  cavity. 

THE  SECOND   CLASS   OF   ANIMALS,   BIRDS    (AVES.) 

As  the  organs  of  prehension  of  this  class  consist  of  a  horny 
substance,  and  are  therefore  not  teeth  properly  speaking,  a 
remark  or  two  is  all  that  is  considered  necessary  to  be  made 
in  reference  to  these  substitutes  or  mere  representatives  of 
teeth. 

It  is  true,  as  has  been  remarked,  that  strictly  speaking, 

*  Some  varieties  in  this  order,  it  is  thought,  have  teeth  proper. 

19 


290  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

the  beak  of  the  bird  is  an  organ  of  prehension  and  mastica- 
tion, and  often  a  powerful  weapon  for  either  offence  or  de- 
fence, though  in  its  form  and  structure  it  is  more  like  the 
claws  and  nails  than  teeth. 

The  beak  in  birds  of  prey  is  hard,  in  water  birds  it  is 
comparatively  soft.  The  form  is  very  various,  and  corre- 
sponds with  the  kind  of  food  and  the  habits  of  the  several 
varieties.  In  some  birds  of  prey  it  is  curved  into  a  "hook 
with  sharp  cutting  edges."  In  others,  as  in  the  stork,  it  is 
straight;  some  have  it  bent  downwards,  others  upwards; 
some  have  it  compressed,  as  the  penguin,  transversely;  and 
others,  as  the  duck,  have  it  flat. 

The  jaws  present,  in  some,  distinct  elevations  or  notches, 
resembling  teeth.  The  duck  has  these  indentations  regu- 
larly arranged,  and  supplied  with  branches  of  the  inferior 
maxillary  nerve. 

THIKD  CLASS  OF  ANIMALS — REPTILES   (REPTILIA.) 

The  teeth  of  this  class,  occupying  a  position  intermediate 
between  those  of  the  bird  and  of  the  .fish,  are  thought  to 
partake  thereby  of  the  characteristics  of  both. 

The  tortoise  has  the  beak  of  the  bird,  and  with  this 
exception  all  other  reptiles  are  said  to  have  true  teeth. 
These  are  pointed  and  conical,  and  resemble  more  those 
of  the  carnivorous  class,  and  form  weapons  of  attack  and 
defence. 

The  number  of  teeth  belonging  to  reptiles  is  not  deter- 
mined, but  it  is  greater  than  in  man.  They  are  fixed  in 
the  jaws,  though  sometimes  as  in  the  serpent,  are  placed 
in  the  palate.  They  are  without  roots,  and  are  fixed  in 
alveoli  which  are  more  narrow  at  their  external  opening 
than  at  the  bottom. 

The  teeth  of  this  class  are  developed  at  a  very  early  age, 
and  always  the  number  is  the  same.  Those  which  have 
just  come  forth  from  the  egg  have  as  many  as  the  adult 
animal,  ten  or  twenty  feet  in  length. 

Eeptiles  shed  their  teeth,  it  seems,  with  greater  fre- 
quency and  facility  than  most  other  animals,  These  or- 


COMPARATIVE  ANATOMY  OF  THE  TEETH. 


291 


B 


gans  grow  with  age,  and  are  found  of  a  size  proportionate 
to  the  dimensions  of  the  animal. 

Serpents  have  teeth  FlG>  80>      B 

both  upon  the  palate 
and  jaws.  The  ven- 
omous teeth  are  at- 
tached to  the  upper 
maxillary  bone,  and 
are  curved  backward 
in  a  semi-circular 
form.  The  roots  are 
situated  in  the  ante- 
rior part  of  the  jaw, 
and  'are  not  mova- 
ble, according  to  Mr. 
Blandin,butare  fixed 
firmly  to  the  bone; 
the  jaw  itself,  which 
is  movable,  causing 
the  apparent  motion. 
These  poisonous  teeth 
are  much  longer  than 
any  other — and  have 
a  canal  running  the 
whole  length  of  the 
teeth,  which  contains 
the  excretory  duct  of 
the  gland  furnishing 
the  poison.  This  ca- 
nal terminates  on  the 
free  extremity  of  the 
tooth  by  an  opening, 
through  which  the  animal  ejects  the  poison.  The  sac  sur- 
rounding the  base  of  the  fang  has  within  it  several  rudi- 

Fio.  80,  A,  B,  C  represent  the  poison  Fangs  of  Serpents.  B  Longitudinal 
section  of  the  fang,  v  poison  duct;  accented  v  its  outlet. 

FIG.  80,  D  represents  also  a  section  of  the  poison  fang  magnified — f  p  showing 
pulp  canal,  calcigerous  tubes,  and  dentine  enclosing  the  poison  canal. 


292  COMPARATIVE  ANATOMY  OF  THE  TEETH. 

mentary  fangs.     As  many  as  eleven  have  been  seen,  so  that 
when  one  is  shed  there  is  another  to  take  its  place. 

All  the  frogs  are  said  to  have  teeth  in  both  jaws,  and 
all,  with  the  exception  of  a  single  variety  called  the  pipa, 
have  teeth  in  the  roof  of  the  palate. 

FOURTH  CLASS — FISHES,  (PISCES.) 

Fish  constitute  the  last  class  of  the  vertehrated  division  of 
the  animal  kingdom.  Their  dental  system  presents  great 
variety,  both  in  number  and  arrangement.  The  teeth  are 
found  in  all  parts  of  the  mouth  and  pharynx,  and  are  distin- 
guished, according  to  their  situation,  into  intermaxillary, 
mandibular,  palatine,  vomerial,  lingual,  bronchial,  and  pha- 
ryngeal. 

The  teeth  of  fish  are  either  received  into  alveolar  cavi- 
ties, and  are  firm  and  immovable,  or  are  removed  from  the 

maxillary  bones,  and  have  not 
the  cavities,  as  in  the  cartila- 
ginous fishes,  except  the  saw 
fish,  and  are  movable  as  in  the 
shark,  which  has  the  power  of 
elevating  and  depressing  its 
teeth. 

The  fact  of  the  teeth  being 
thus  removed  from  the  bone  and 
connected  with  mucous  mem- 
brane, is  regarded  as  conclu- 
sive in  reference  to  the  theory  of  their  origin  from  mucous 
membrane. 

The  form  of  the  teeth  of  fish  is  exceedingly  various — 
some  are  conical,  others  flattened;  the  conical  form  the 
largest  number,  and  sometimes  present  a  single  point,  at 
others  two  or  three  points.  In  a  variety  called  the  scarius 
there  are  five  or  six  rows,  composed  each  of  five  or  six  teeth 
united  by  a  species  of  cement. 

FIG.  81  represents  the  teeth  of  the  Rock  Fish,  (labrus.)  They  are  attached 
to  the  inferior  pharyngeal  bone,  are  very  numerous,  are  scattered  over  a  broad 
surface,  and  are  said  to  resemble  a  «*  pavement." 


COMPARATIVE  ANATOMY  OF  THE  TEETH.  293 

The  osseous  teeth,  fixed  in  alveoli,  are,  after  their  full 
development,  described  as  being  "closely  soldered  to  the 
circumference  of  the  cavity  in  which  they  are  placed." 

Those  fish  whose  teeth  are  sharp,  with  a  strong  incli- 
nation backwards  as  in  the  pike,  or  tooth-like  and  cutting 
as  in  the  shark,  are  regarded  as  the  most  carnivorous  and 
voracious.  Those  on  the  other  hand  whose  teeth  are  flat- 
tened, or  only  pharyngeal,  are  viewed  as  the  least  carnivor- 
ous and  most  peaceable  in  their  dispositions. 

SECOND  DIVISION  OP  THE  ANIMAL  KINGDOM. 

THE  INVERTEBRATA  OR  ANIMALS  DESTITUTE  OF  A  SPINE. — 
The  teeth  of  this  division  have  an  analogy  of  function 
with  those  of  the  vertebrata,  being  situated,  many  of 
them,  at  or  near  the  mouth  of  the  alimentary  tube,  and 
laying  hold  of,  retaining,  and  dividing  the  food — thus 
performing  the  functions  of  prehension  and  mastication, 
though  in  structure  they  are  considered  by  some  as  farther 
removed  from  true  teeth  than  the  hair. 

The  teeth  of  the  invertebrated  division  are  mostly  found 
in  the  stomach — a  very  singular  and  striking  fact;  and  Mr. 
Blandin  remarks,  "  The  higher  the  animal  is  elevated  in 
the  scale,  the  higher  are  the  dental  organs  elevated  in  the 
alimentary  canal. 

"In  the  Crustacea  andmollusca  they  are  placed  principally 
in  the  stomach.  In  fishes  they  reach  the  pharynx.  In  rep- 
tiles the  posterior  part  of  the  mouth— whilst  in  the  mam- 
malia they  are  confined  to  the  anterior  and  lateral  parts  of 
the  mouth." 

In  the  Crustacea  the  dental  organs  found  in  the  stomach 
consist  of  calcareous  matter  placed  on  a  kind  of  skeleton. 
This  so-called  skeleton  of  the  stomach  is  composed  of 
transverse  and  lateral  ribs,  to  which  these  teeth  are  at- 
tached. Upon  the  lateral  ridges  the  two  larger  teeth  are 
placed  and  have  flat  crowns,  with  depressions.  The  crown 
in  the  crab  is  striated,  and  has  on  its  inferior  border  large 
"  denticulations." 

The  great  lobster  is  described  as  having  nine  of  the  rib- 


294  ACTIVE  OKGANS  OF  MASTICATION. 

like  elevations.  At  tlie  point  of  junction  of  the  lateral  and 
transverse  ridges,  another  ridge  is  spoken  of  as  branching 
off,  which  has  a  tooth,  and  also  three  and  sometimes  five 
sharp,  hooked,  and  small  pointed  elevations. 

The  hooked  teeth  are  represented  as  seizing  the  food  and 
carrying  it  between  the  teeth  with  flattened  crowns. 

Insects  and  worms  cannot  be  said  to  have  any  organs 
which  can  be  compared  to  teeth.  The  stomachs  of  some  of 
them  seem  to  be  furnished  with  "  scales  or  horny  hooks," 
which  are  supposed  to  be  intended  for  a  kind  of  mastication. 

SECTION   VI. 

ACTIVE  ORGANS  OF  MASTICATION,   CONSISTING  OF  MUSCLES. 

1.  Masseter  Muscle. — The  same  dissection  made  for  the 
muscles  of  prehension  will  exhibit  this  muscle. 

FIG.  82.  The    masseter    (fuuHtuofUM,   I 

chew)  is  a  superficial,  thick, 
and  strong  muscle,  situated  at 
the  side  and  back  part  of  the 
face,  and  extended  between  the 
zygoma  and  angle  of  the  lower 
jaw.  It  consists  of  two  portions, 
an  anterior  and  posterior,  or 
superficial  and  deep,  which  de- 
cussate. The  anterior  is  the 
larger,  and  arises  tendinous  from  the  inferior  edge  of 
the  malar  bone,  and  from  the  point  where  it  unites 
with  the  maxillary.  The  posterior  arises  fleshy  from  the 
zygomatic  arch  as  far  back  as  the  glenoid  cavity.  The 
fibres  of  the  anterior  portion  pass  backwards  and  down- 
wards; of  those  of  the  posterior,  some  descend  obliquely 

FIG.  82  Lateral  view  of  the  Muscles  of  the  face,  cranium,  and  external 
ear.  1  Occipito-frontalis,  2  Orbicularis  palpebrarum,  3  Pyramidalis  nasi,  4 
Compressor  nasi,  5  6  Levator  labii  superioris  alseque  nasi,  7  Zygomaticus  mi- 
nor, 8  Zygomaticus  major,  9  Masseter  muscle,  10  Buccinator,  11  Depressor 
anguli,  or  triangularis  orisj  12  Depressor  labii  inferioris,  13  Orbicularis  oris, 
14  Anterior  auris,  15  Superior  auris,  16  Posterior  auris,  17  External  lateral 
ligament,  18  Deep-seated  portion  of  masseter,  19  Fascia  temporalis. 


ACTIVE  ORGANS  OF  MASTICATION.  295 

forwards,  others  vertically,  and  both  portions  are  inserted, 
tendinous  and  fleshy,  into  the  external  surface  of  the 
angle  and  ramus  of  the  lower  jaw  as  high  as  the  coronoid 
process. 

Function.  If  the  anterior  portions  of  both  muscles  act 
together,  the  jaw  is  carried  forwards — if  the  posterior  act, 
it  is  carried  backwards ;  if  both  anterior  and  posterior,  on 
opposite  sides,  act  together,  the  lower  jaw  will  be  power- 
fully raised  to  the  upper.  If  the  superficial  portion,  on 
the  one  side,  act  alone,  it  can  throw  the  chin  to  the  oppo- 
site side.  If  the  deep  portion  act  by  itself,  it  can  rotate 
the  jaw  to  its  own  side. 

This  muscle  is  one  of  the  chief  agents  in  mastication,  as 
it  has  the  power  of  directly  bringing  the  lower  jaw  to  the 
upper,  and  thereby  dividing  the  food,  and  also  of  rotating 
it,  whereby  its  trituration  is  effected. 

The  masseter  is  covered  by  the  skin,  a  few  fibres  of  the 
platysma,  orbicularis  palpebrarum,  and  zygomatic  muscles, 
as  well  as  by  a  part  of  the  parotid  gland  and  duct,  and  the 
transverse  facial  vessels  and  nerves. 

2.  Temporalis  Muscle — (tempora,  the  temples.) 

Dissection. — Make  an  incision  along  the  semicircular 
ridge  upon  the  side  of  the  cranium,  extending  from  the 
external  angular  process  of  the  FIG.  83. 

frontal  bone,  along  the  parie- 
tal, back  to  themastoid  process 
of  the  temporal  bone.  Turn 
this  portion  of  skin  down  to 
the  zygoma,  and  the  temporal 
aponeurosis  is  brought  to  view. 
This  is  a  white,  strong,  and 
shining  fascia,  which  is  at- 
tached above  to  the  semicir- 
cular ridge,  and  below  to  the 
zygoma.  It  covers  the  temporal  muscle — is  thin  above 
where  the  muscle  is  seen  through  it,  and  thick  below  where 

Fio.  83  Temporal  Muscle,  the  fascia  being  removed.  1  Temporal  muscle, 
2  External  lateral  ligament,  3  Insertion  of  temporal  muscle. 


296  ACTIVE  ORGANS  OF  MASTICATION. 

it  consists  of  two  layers  separated  by  some  fat,  vessels,  and 
nerves.  Turn  this  fascia  down  to  the  zygoma,  and  the  up- 
per and  larger  portion  of  the  temporal  muscle  is  exposed. 
Now  saw  through  the  zygomatic  arch  at  either  end,  and 
turn  it  down  with  the  masseter,  and  we  have  brought  to 
view  the  lower  portion  of  the  temporal.  Thus  exposed,  the 
temporal  muscle  is  seen  to  arise  on  the  side  of  the  cranium 
from  the  whole  length  of  the  semicircular  ridge,  and  from 
the  surface  below  this  ridge,  formed  by  the  frontal,  parie- 
tal, squamous  portion  of  the  temporal,  and  greater  wing 
of  the  sphenoid  bone,  as  low  down  as  its  crest ;  and  from 
the  under  surface  of  the  fascia  temporalis.  From  this  ex- 
tensive origin,  the  fibres  converge  to  a  strong  tendon, 
which  is  inserted  into  the  coronoid  process,  nearly  sur- 
rounding it,  and  continues  forwards  as  far  as  the  last 
molares. 

Function. — To  bring  the  lower  jaw  to  the  upper,  in  the 
cutting  of  the  food  in  mastication.     The  posterior  fibres,  by 
drawing  the  lower  jaw  backwards,  are  a  great  security 
against  dislocations  of  this  bone. 
3.  Pterygoideus  externus. 

Dissection. — Turn  off  the  masseter  muscle  close  to  the 
bone,  and  take  out  a  section  of  the  ramus  by  sawing  be- 
FlG-  84-  tween  its  angle,,  and  the  root  of 

the  condyle,   and    the    pterygoid 
muscles  will  be  exposed. 

The  pterygoideus  externus  is  a 
short  triangular  muscle,  running 
horizontally  and  situated  deep  be- 
hind the  ramus  of  the  lower  jaw. 
It  arises  by  two  heads — the  one 
from  the  crest  on  the  great  wing 
of  the  sphenoid  bone,  at  its  root,  the  other  from  the  outer 
surface  of  the  external  pterygoid  plate,  and  tuberosity  of 
the  upper  maxilla — the  two  portions  converge  and  pass 

FIG.  84  represents  the  Pterygoid  Muscles;  the  zygomatic  arch  and  ramus  of 
the  lower  jaw  being  removed,  a  6  Pterygoideus  externus.  c  Pterygoideus 
interims. 


ACTION  OP  THE  MUSCLES  OF  MASTICATION.  297 

backwards  and  outwards,  to  be  inserted  into  the  internal 
and  anterior  part  of  the  neck  of  the  lower  jaw  and  the  in- 
terarticular  cartilage. 

Function. — When  one  muscle  acts,  it  turns  the  jaw  to  the 
opposite  side;  when  both  act  alternately,  they  give  the  ro- 
tatory or  grinding  motion.  If  they  act  together,  the  jaw  is 
thrown  forward. 

4.  Pterygoideus  internus,  (Fig.  84.) 

This  muscle  is  thick  and  short,  and  situated  behind  the 
ramus  and  angle  of  the  inferior  maxilla.  It  is  inferior  to 
the  external  pterygoid,  and  parallel  to  the  superficial  layer 
of  the  masseter. 

It  arises  fleshy  and  tendinous  from  the  inner  surface  of 
the  external  pterygoid  plate,  and  pterygoid  process  of  the 
palate  bone,  occupies  the  greater  portion  of  the  pterygoid 
fossa,  and  passes  downwards  and  outwards  to  be  inserted 
tendinous  and  fleshy  on  the  inner  surface  of  the  angle  of 
the  jaw. 

Function. — It  is  a  rotator  of  the  jaws  and  thus  co-operates 
with  the  external  pterygoid  in  triturating  the  food. 

The  two  pterygoid  muscles  arising  so  near  each  other 
and  passing  in  different  directions,  the  one  downwards, 
and  the  other  upwards  and  outwards,  a  triangular  space  is 
left  between  them,  containing  a  quantity  of  fat,  the  inter- 
nal maxillary  artery  and  vein,  the  inferior  dental  and  gus- 
tatory nerves,  and  a  portion  of  the  parotid  gland.  The  in- 
ternal maxillary  artery  occasionally  passes  between  the 
origins  of  the  external  pterygoid  muscles,  as  it  is  about  en- 
tering the  spheno-maxillary  fossa. 

COMBINED  ACTION  OF  THE  MUSCLES  OF  MASTICATION. 

The  conjoint  action  of  these  muscles  is  the  effective 
agent  in  mastication.  The  masseter  and  temporal  are 
principally  employed  in  raising  the  lower  jaw  to  the 
upper,,  and  thus  dividing  the  food,  while  the  pterygoid 
in  rotating  the  lower  jaw  upon  the  upper,  produces  the 
grinding  motion,  and  thus  reduces  the  food  to  the  smallest 
portions,  suitable  for  deglutition.  The  anterior  layer  of  the 


298  ORGANS  OF  INSAUVATION. 

masseter  and  the  posterior  fibres  of  the  temporal  can  also  as- 
sist the  pterygoid  in  the  grinding  process,  while  the  buccina- 
tor comes  in  to  their  aid  by  keeping  the  food  under  the  teeth. 
So  that  the  whole  are  so  adapted  to  each  other  as  to  act  in 
the  utmost  harmony  for  the  most  perfect  performance  of  the 
function  of  mastication. 

Blood-vessels,  (Fig.  'TS.) — The  arteries  supplying  the 
muscles  of  mastication  come  from  the  temporal,  the  external 
and  internal  maxillary  arteries,  and  are  named  according 
to  the  muscles  they  supply,  as  the  temporal,  masseteric,  and 
pterygoid  branches.  The  veins  correspond  to  the  arteries 
and  return  the  blood  into  the  external  jugular. 

Nerves,  (Fig.  74.) — The  nerves  supplying  the  muscles  of 
mastication  come  from  the  fifth  and  seventh  pair.  The 
motor  division  of  the  inferior  maxillary  branch  of  the  fifth, 
seen  in  the  zygomatic  fossa,  sends  off  five  muscular  branch- 
es, i.  e.  the  two  deep  temporal,  masseteric,  buccal  and  ptery- 
goid, going  to  the  muscles  of  the  same  name.*  The  portio 
dura  or  facial  nerve  is  a  branch  of  the  seventh,  which 
also  supplies  the  muscles  of  mastication.  It  is  situated  in 
the  substance  of  the  parotid  gland,  anastomoses  freely  with 
the  fifth,  and  is  described  more  minutely  under  the  head 
of  organs  of  expression,  which  see. 

SECTION  VII. 
ORGANS  OF  INSALIVATION,   COMPRISING  THE  SALIVARY  GLANDS. 

The  salivary  glands  are  six  in  number — three  on  each 
side  of  the  face,  i.  e.  the  parotid,  submaxillary ,  and  sublin- 
gual.  These  glands  belong  to  the  conglomerate  order, 
that  is,  they  consist  of  numerous  little  follicles,  (Fig.  85,  B,) 
averaging  about  the  one-twelve-thousandth  of  an  inch  in 
diameter,  surrounded  by  a  plexus  of  capillary  blood-vessels, 
and  presenting  the  appearance  of  a  multitude  of  small 
granules — each  being  a  gland  in  miniature,  and  each,  conse- 
quently, having  its  own  artery,  vein,  and  excretory  duct. 
It  is  by  the  combination  of  these  various  little  excre- 

*See  inferior  maxillary  nerve,  under  the  head  of  nerves  supplying  the  teeth, 
for  a  more  minute  account. 


ORGANS  OF  INSALIVATION.  299 

tory  ducts  that  one  common  duct  is  formed,  whose  office 
is  to  carry  the  saliva,  furnished  by  these  glands,  into  the 
mouth. 

A  FIG.  85.  B 


These  salivary  glands  are  developed  from  the  mucous 
membrane  of  the  mouth,  which  being  reflected  in  the  form 
of  a  tube,  sends  off  bud-like  processes  whose  ultimate  ter- 
minations constitute  the  follicles  just  described. 

1.  The  Parotid. 

Dissection. — This  gland,  so  called  from  its  situation 
about  the  ear,  (^apa,  near,  or$  <*toft  the  ear,)  is  brought  to 
view  by  the  same  dissection,  for  exposing  the  organs  of 
prehension.  It  is  covered  by  a  dense  fascia,  the  fascia 
superficialis,  continued  from  the  neck,  which  sends  down 
into  its  substance  numerous  processes  which  serve  to  sep- 
arate its  granules,  and  conduct  to  it  its  blood-vessels.  This 
fascia  must  be  separated  from  its  strong  attachment  to  the 
cartilaginous  portion  of  the  meatus  externus,  and  removed, 
when  the  parotid  will  be  fairly  exposed.  It  presents  a 
pale,  rough,  granulated  surface,  and  is  the  largest  of  the 
salivary  glands.  It  has  no  regular  figure,  but  occupies  the 
space  reaching  from  the  zygoma  above,  to  the  angle  of  the 
jaw  below ;  and  from  the  mastoid  process  and  sterno-cleido 
mastoid  muscle  behind,  to  a  short  distance  over  the  mas- 
seter  muscle  in  front — while  in  depth,  it  passes  behind  the 

FIG.  85,  A  represents  the  Salivary  Glands.  1  Parotid  gland,  2  Duct  of 
Steno,  3  Submaxillary  gland,  4  Duct  of  Wharton  or  submaxillary  duct,  5 
Sublingual  gland. 

FIG.  85,  B  represents  a  lobule  of  the  parotid  gland  of  a  new-born  infant 
injected  with  mercury— magnified  fifty  diameters. 


300  ORGANS  OF  INSALIVATION. 

ramus  of  the  jaw,  extends  back  to  the  styloid  process,  which, 
with  its  muscles,  it  envelops — is  in  contact  with  the  inter- 
nal carotid  artery,  jugular  vein,  and  eighth  pair,  or  par- 
vagum  nerves,  and  finally  fills  the  posterior  part  of  the* 
glenoid  cavity  of  the  temporal  bone. 

Each  of  the  granules  composing  this  gland  has,  as 
already  stated,  an  excretory  duct,  which,  uniting  with  its 
fellows,  forms  one  common  duct  called  the  parotid  duct,  or 
the  duct  of  Steno,  which  is  seen  issuing  from  the  gland  at 
its  anterior  and  posterior  part,  and  is  then  traced  passing 
over  the  masseter,  about  an  inch  below  the  zygoma,  and 
through  a  quantity  of  soft  lobulated  fat,  on  the  anterior 
edge  of  this  muscle.  It  then  pierces  the  buccinator  at 
its  upper  part,  opening  into  the  mouth  by  a  papilla  (some- 
times there  is  none)  opposite  the  second  or  third  molar 
tooth  of  the  upper  jaw. 

A  line  drawn  from  the  lobe  of  the  ear  to  a  point  midway 
the  root  of  the  nose  and  lower  margin  of  the  upper  lip, 
will  give  the  direction  of  the  parotid  duct.  This  duct  has 
two  coats — an  outer  of  condensed  cellular,  and  an  inner  of 
mucous  membrane.  Between  the  zygoma  and  this  duct,  a 
small  glandular  mass  is  occasionally  seen,  having  a  small 
duct  which  either  unites  with  the  duct  of  Steno,  or  enters 
separately  into  the  mouth.  It  is  called  the  socia  parotidis. 

Function. — The  use  of  this  gland  is  to  secrete  the  larger 
portion  of  the  saliva  with  which  the  mouth  is  supplied, 
and  which  is  carried  thither  by  the  duct  of  Steno. 

2.  The  Submaxillary  Gland—  (Fig.  85.) 

Dissection. — Make  an  incision  along  the  base  of  the  lower 
jaw,  from  the  chin  back  to  the  angle,  and  along  the  ramus, 
the  same  as  for  the  organs  of  prehension.  Make  a  second 
incision  along  the  median  line  at  the  upper  part  of  the 
neck  as  far  as  the  hyoid  bone,  commencing  at  the  lower 
portion  of  the  symphysis  menti,  and  turn  down  the  skin 
obliquely  towards  the  clavicle.  This  exposes  the  broad 
muscle  of  the  neck,  the  platysma  myoides,  and  the  superfi- 
cial cervical  fascia.  Turn  these  down,  and  the  submaxil- 
lary  gland  is  exposed.  This  gland  is  second  in  size  to  the 


ORGANS  OF  INSALTVATION.  301 

parotid — is  covered  by  cellular  structure,  and  surrounded 
by  lymphatic  glands.  It  is  of  an  oval  shape,  and  pale 
color,  and  occupies  a  triangular  space  at  the  upper  part  of 
the  neck,  bounded  anteriorly  by  the  base  of  the  lower 
jaw — posteriorly  and  internally  by  the  tendon  and  ante- 
rior belly  of  the  digastric  muscle- — externally  by  the  stylo 
maxillary  ligament,  and  the  pterygoideus  internus  muscle. 

The  structure  of  the  submaxillary  is  the  same  as  the 
parotid,  consisting  of  granules  having  each  an  excretory 
duct,  which  unite  together  into  one  common  duct,  called 
the  duct  of  Wharton,  This  duct  leaves  the  gland  at  its  an- 
terior or  middle  portion,  and  winds  above  the  mylo-hyoid 
muscle,  between  it  and  the  hyoglossus,  thence  passes  for- 
wards between  the  genio-hyo-glossus  and  sublingual  gland, 
the  latter  of  which  it  touches,  and  finally  ends  in  a  prom- 
inent papilla,  by  an  open  orifice,  on  either  side  of  the 
frenum  linguae.  This  duct  has  thinner  walls,  but  a  larger 
calibre  than  that  of  the  parotid.  It  is  about  two  and  a  half 
inches  long,  and  is  accompanied  by  the  gustatory  nerve. 

function. — To  secrete  saliva,  which  is  carried  by  the  duct 
of  Wharton  into  the  mouth.  If  this  duct,  from  any  cause, 
be  obstructed,  the  saliva  accumulates  on  the  under  surface 
of  the  tongue,  beneath  its  tip,  forming  a  tumor  called 
ramula. 

3.  The  Sublingual  Gland— (Fig.  85.)— This  gland,  oblong 
in  shape,  and  of  all  the  salivary  glands,  smallest  in  size,  is 
seen  by  raising  the  tip  of  the  tongue,  and,  as  its  name  im- 
plies, is  on  the  under  surface  of  its  anterior  and  lateral  part. 
It  is  covered  by  the  mucous  membrane,  and  rests  on  the  mylo 
hyoid  muscle.  It  is  related  to  the  genio-hyo-glossus  and  duct 
of  Wharton  internally,  and  is  connected  behind  with  a  pro- 
cess of  the  submaxillary  gland.  Its  excretory  ducts  do  not 
form  a  common  duct,  but  have  been  seen  to  enter  the  mouth 
separately  by  fifteen  or  twenty  small  orifices,  on  a  kind  of 
fold  or  crest  of  the  mucous  membrane,  between  the  tongue 
and  inferior  bicuspid  and  canine  teeth.  The  ducts,  some  of 
them,  enter  the  duct  of  Wharton. 

Function. — The  same  as  the  parotid  and  submaxillary. 


302  OKGANS  OF  INSALIVATION. 

Blood-vessels. — The  salivary  glands  are  abundantly  sup- 
plied with  blood-vessels.  The  arteries  going  to  the  parotid 
come  from  the  external  carotid  (Fig.  73)  and  its  branches 
the  facial,  superficial  temporal,  transverse  facial,  and  an- 
terior and  posterior  auricular.  The  veins  take  the  same 
direction  as  the  arteries,  .have  the  same  names,  and  termi- 
nate in  the  jugular.  The  submaxillary  is  supplied  by  the 
facial  and  lingual.  The  sublingual  gland  has  its  supply 
from  the  sublingual  and  the  submental  branches.  The 
veins  correspond  to  the  arteries. 

Nerves. — The  parotid  is  supplied  with  nerves  from  the 
auricular  branch  of  the  inferior  maxillary,  (Fig.  74,)  and 
auricular  branch  of  the  cervical  plexus;  the  facial,  and 
filaments  of  the  sympathetic,  from  those  of  the  external 
carotid  artery.  The  submaxillary  gland  is  supplied  from 
the  submaxillary  ganglion,  the  lingual,  and  mylo-hyoid 
branch  of  the  inferior  dental  nerve. 

Saliva  is  a  term  indiscriminately  applied  to  the  secre- 
tions furnished  by  the  salivary  glands,  and,  until  very 
recently,  has  been  supposed  to  be  of  the  same  character, 
whatever  its  source.  It  was  generally  examined  mixed 
with  the  other  fluids  of  the  mouth,  so  that  its  precise  char- 
acter could  not  be  definitely  fixed.  It  was  regarded  as 
alkaline,  in  a  state  of  health,  which  more  recent  observa- 
tions confirm ;  while  the  fluids  of  the  buccal  mucous  mem- 
brane have  been  found  to  be  acid. 

The  microscope  reports  the  saliva  to  contain  minute 
corpuscles,  and  large  epithelial  scales  derived  from  the 
mucous  membrane  of  the  mouth.  Its  chemical  constitution 
is  furnished  by  the  chemists  Frerichs  and  Wright,  two 
of  the  most  recent  authorities,  and  whose  analysis  is  re- 
garded as  the  most  accurate.  The  former  makes  saliva  to 
consist  in  a  hundred  parts :  of  water,  994.10;  solid  matters, 
5.90;  ptyaline,  1.41;  mucus  and  epithelium,  2.13;  fatty 
matter,  .07;  sulpho-cyanide  of  potassium,  .10;  alkaline  and 
earthy  chlorides  and  phosphates,  2.19. 

Wright's  analysis  is  in  a  hundred  parts:  water,  988.10; 
solid  matters,  11.90;  ptyaline,  1.80;  mucus  and  epithelium, 


ORGAN'S   OF  DEGLUTITION.  303 

2.60;  fatty  matter,  .50;  albumen  with  soda,  1.70;  sulpho- 
cyanide  of  potassium,  .90;  alkaline  andi  earthy  salts,  3.20; 
loss,  1.20. 

Ptyaline  is  the  term  applied  to  a  substance  upon  which 
the  peculiar  properties  of  the  saliva  are  made  to  depend, 
and  is  regarded  as  albuminous  in  its  character.  The  ptya- 
line  of  Wright,  however,  differs  from  that  of  other  observers. 

Now  the  experiments  of  M.  Bernard  seem  to  show  that 
saliva  is  not  only  not  the  same,  but  presents  quite  different 
properties  and  uses,  as  obtained  from  the  parotid,  submax- 
illary,  and  sublingual  glands.  That  from  the  parotid  is 
found  to  be  thin,  watery,  abundant,  (varying,  however, 
according  to  the  food,)  readily  penetrating  substances,  and 
believed  to  be  especially  designed  to  aid  in  mastication 
and  assimilation,  and  is  the  fluid  chiefly  concerned  in  form- 
ing the  food  into  a  bolus,  for  its  onward  passage  from  the 
mouth  into  the  pharynx. 

The  saliva  from  the  sublingual  is  described  as  "viscous 
and  adhesive,  incapable  of  penetrating  substances,  but  ad- 
mirably adapted  to  cover  their  surface  with  a  viscid  coat- 
ing, which  much  facilitates  their  being  swallowed,"  and  is 
the  fluid  especially  concerned  in  deglutition.  This  gland 
is  said  to  remain  quiet  during  mastication,  but  to  begin  to 
act  as  soon  as  deglutition  commences. 

The  submaxillary  gland  furnishes  a  saliva  partaking  of 
the  characters  of  both  the  former,  and  supposed  to  be 
especially  concerned  with  the  sense  of  taste,  diminishing 
the  pungency  of  sapid  bodies,  and  reducing  their  cohesion. 

SECTION  VIII. 
ORGANS  OF  DEGLUTITION. 

The  organs  of  deglutition  consist  of  the  muscles  forming 
the  floor  of  the  mouth,  the  pharynx,  soft-palate,  and  tongue. 

THE  MUSCLES. 

Dissection. — The  same  incisions  are  required  as  were 
resorted  to  in  exposing  the  submaxillary  gland. 


304 


ORGANS  OF  DEGLUTITION. 


Digastricus  Musde—fa,  twice,  ywrcp,  belly.)  This  mus- 
cle is  composed  of  two  fleshy  bellies,  an  anterior  and  poste- 
rior, with  a  round  tendon  in  the  centre.  It  is  situated 
below  the  base  of  the  lower  jaw,  at  the  anterior  and  lat- 
eral portions  of  the  neck.  It  arises  from  the  groove  on  the 
inner  side  of  the  mastoid  process  of  the  temporal  bone, 
descends  fleshy,  obliquely  forwards  and  inwards,  till  it  ap- 
proaches the  os-hyoides,  when  it  becomes  tendinous,  per- 
forates the  stylo-hyoid  muscle,  connects  itself  by  a  strong 
fascia— sometimes  by  a  ring-like  pully— to  the  hyoid  bone, 
FIG.  86.  and  then  passes  for- 

ward again  fleshy, 
forming  the  anterior 
belly,  to  be  inserted 
into  a  depression, 
close  to  the  sym- 
physis,  on  the  in- 
ner side  of  the  lower 
jaw. 

Function. — To  draw 
down  the  lower  jaw, 
and  to  elevate  the 
os-hyoides,  tongue 
and  larynx,  when 
the  mouth  is  closed. 
When  the  anterior  belly  acts  it  can  draw  these  parts  for- 
wards. When  the  posterior  acts  they  are  drawn  backwards. 
It  exerts,  by  these  varied  actions,  great  influence  over 
deglutition. 

Mylo-Jiyoideus ,  (/u&.q,  a  molar  or  grinder,)  Fig.  86,  is  a 
broad,  triangular  muscle,  forming  the  floor  of  the  mouth, 

FIG.  86  represents  the  muscles  at  the  base  of  the  lower  jaw,  and  upper  and 
front  part  of  neck.  1  Posterior  belly  of  the  digastricus.  2  Its  anterior  belly 
3  Ligamentous  loop  through  which  it  plays.  4  Stylo-hyoideus.  5  Mylo- 
hyoideus.  6  Genio-hyoideus.  7  Tongue.  8  Hyo-glossus.  9  Stylo-glossus. 
10  Stylo-Pharyngeus.  11  Sterno-cleido-mastoideus.  12  Its  sternal  origin.  13 
Clavicular  attachment.  14  Sterno-hyoideus.  15  Sterno-thyroideus.  16  Thyro- 
hyoideus.  17  Anterior  belly  of  omo-hyoideus.  18  Posterior  belly  of  omo- 
hyoideus.  19  Anterior  edge  of  trapezius.  20  Scalenus  anticus.  21  Scalenus 
posticus.  22  Scalenus  medius. 


ORGANS  OF  DEGLUTITION.  305 

and  fully  exposed  on  removing  the  anterior  belly  of  the 
digastric.  It  arises  from  the  myloid  ridge  on  the  inner 
side  of  the  lower  jaw,  and  descends  inwards  and  backwards 
to  be  inserted  into  the  base  of  the  os-hyoides,  and  along 
with  its  fellow  into  the  middle  tendinous  line,  between 
that  bone  and  the  chin. 

Function. — To  bring  the  os-hyoides  forward  and  pro- 
ject the  tongue.  This  muscle  is  covered  by  the  digastric 
muscle,  the  submaxillary  gland,  the  platysma  and  fascia, 
and  lies  upon  the  genio-hyoid,  hyo-glossus,  and  stylo- 
glossus  muscles — the  duct  of  Wharton,  lingual  and  gus- 
tatory nerves,  and  sublingual  gland. 

Eemove  this  muscle  by  dividing  it  on  either  side,  and  we 
see  the  next  in  order,  i.  e.  Genio-hyoideus ,  (ysvswv,  the  chin,) 
Fig.  8*7-  It  arises  from  the  posterior  mental  tubercle  above 
the  digastric,  by  a  small  tendon,  and  descends  backward  to 
be  inserted  into  the  base  of  the  os-hyoides.  Function. — To 
bring  the  os-hyoides  forward,  and  to  protrude  the  tongue 
against  the  incisor  teeth,  or  out  of  the  mouth. 

Genio-Jiyo-glossus ,  „ 

(yxwtfora,  the  tongue,)  is 
seen  by  removing  •  the 
genio-hyoideus.  It  is  a' 
triangular  muscle_,  and 
arises  by  a  small  tendon 
from  the  posterior  men-l 
tal  tubercle,  above  the 
genio-hyoideus  and  be- 
low the  frenum  linguae, 
and  is  inserted  into  the 
tongue  along  the  mesial 
line  its  whole  length, 
and  into  the  body  of  the 
os-hyoides.  Its  fibres  radiate  in  different  directions;  some 

FIG.  87  represents  a  side  view  of  the  Tongue  and  its  principal  Muscles. 
1  Mastoid  process.  2  Coronoid  process.  3  Stylo-glossus  muscle.  4  Hyo- 
glossus.  5  Genio-hyo-glossus.  6  Genio-hyoideus.  7  Symphysis  menti.  8 
Styloid  process. 

20 


306  SOFT  PALATE. 

pass  forward  to  the  tip  of  the  tongue;  others  backward, 
while  another  set  are  in  the  middle. 

Function. — The  anterior  fibres  can  depress  the  tip  of  the 
tongue,  the  posterior  bring  forward  the  os-hyoides  and 
protrude  the  tongue,  while  the  middle  set  can  make  it  con- 
cave from  side  to  side. 

Hyo-glossus  (Fig.  87)  is  a  quadrilateral  muscle,  arising 
from  the  body  and  whole  of  the  cornu  of  the  os-hyoides,  and 
inserted  into  the  side  of  the  tongue  between  the  stylo- 
glossus  and  the  lingualis.  Function. — To  depress  the  sides 
of  the  tongue,  and  thus  render  its  dorsum  convex. 

Stylo-glossus  (Fig.  87,)  arises  tendinous  and  slender  from 
the  styloid  process  near  its  apex  or  free  extremity,  and  from 
the  stylo-maxillary  ligament,  and  is  inserted  in  two  por- 
tions, into  the  side  of  the  tongue — one  portion  blending 
with  the  hyo-glossus,  and  the  other  being  continued  for- 
ward to  the  tip  of  the  tongue. 

Function. — To  raise  the  tip  of  the  tongue  against  the 
incisor  teeth,  and  draw  it  backward,  and  to  one  side. 

Stylo-Jiyoideus  (Fig.  86)  is  a  small,  delicate  muscle,  arising 
near  the  base  of  the  styloid  process,  on  its  outer  side,  pass- 
ing obliquely  forwards  and  inwards,  parallel  to  the  poste- 
rior belly  of  the  digastric,  whose  tendon  perforates  it.  It 
is  inserted  into  the  body  of  the  os-hyoides.  Function. — To 
draw  back  the  os-hyoides  and  tongue,  and  thus  assist  the 
posterior  belly  of  the  digastric.  A  ligament,  called  stylo- 
hyoid,  often  accompanies  this  muscle,  and  is  sometimes 
found  ossified. 

SOFT  PALATE. 

The  palate  has  been  divided  into  hard  and  soft.  The 
hard  is  composed  of  the  palatine  plate  of  the  palate 
bones.  The  soft  palate  is  attached  to  the  posterior  mar- 
gin of  the  hard,  and  consists  of  a  dense  aponeurosis, 
muscles  and  glands,  enclosed  in  mucous  membrane.  The 
soft  palate,  (velum  pendulum  palati,*)  on  depressing  the 
lower  jaw,  is  seen  at  the  posterior  part  of  the  mouth,  sus- 
pended transversely  in  the  form  of  a  membranous  curtain. 


SOFT  PALATE*.  307 

* 

This  pendulous  portion  is  the  vertical  or  inferior  part, 
while  above,  the  soft  palate  is  extended  backward  on  a 
level  with  the  hard,  forming  what  is  called  its  horizontal 
portion,  and  thus  increasing  the  palatine  arch. 

The  velum  palati  is  a  membranous  valve  separating  the 
mouth  from  the  pharynx  and  posterior  nares,  and,  in  fact, 
acts  the  part  of  a  double  FIG. 

valve.  In  deglutition,  this 
velum  is  raised  and  applied 
to  the  posterior  nares,  to  pre- 
vent the  food  from  passing  in 
this  direction  when  entering 
the  pharynx,  and  after  the 
food  has  entered  the  pharynx 
it  falls  down  into  its  original 
position,  and  prevents  the 
return  of  the  food  into  the  cavity  of  the  mouth.  The  velum 
presents  a  broad,  quadrilateral  shape,  and  has  two  sur- 
faces— the  one  looking  towards  the  tongue — the  lingual; 
the  other  towards  the  nose — the  nasal  surface.  The  lin- 
gual surface  presents,  along  its  middle,  a  white  line,  called 
the  raphe ;  and  from  the  centre  of  the  velum  there  is  seen 
a  depending  portion  called  the  uvula,  which  divides  it  into 
two  lateral  halves.  In  the  raphe  is  situated  that  congeni- 
tal division  of  the  velum  called  cleft  palate.  On  either 
side  of  the  uvula  the  velum  presents  two  lateral  curvatures, 
an  anterior  and  posterior,  called  the  anterior  and  posterior 
lateral  half  arches.  The  anterior  half  arches  proceed  from 
the  base  of  the  uvula,  outward,  having  their  concavit}r 
downward  to  the  sides  of  the  tongue.  The  posterior  half 
arches,  proceeding  also  from  the  uvula,  pass  downward 
and  backward  to  the  sides  of  the  pharynx.  The  space 
between  the  anterior  and  posterior  half  arches  is  called 
the  fauces,  and  is  occupied  by  the  tonsils.  The  opening 

FIG.  88  represents  the  muscles  of  the  Soft  Palate,  a  Roof  of  the  mouth  ; 
b  b  Levator  palate  ;  c  Cuneiform  portion  of  the  sphenoid ;  d  d  Eustachian 
tubes;  t  Circumflexus,  or  tensor  palati  muscle ;/ Azygos  uvula;  gg  Palato 
pharyngeus. 


308  SOFT  PALATE. 

between  the  anterior  half  arches  is  the  isthmus  of  the 
fauces. 

The  tonsils  or  amygdalae,  (o/wySatoa,  an  almond,)  situated 
as  just  stated  in  the  fauces,  consist  of  mucous  follicles  col- 
lected together  in  an  almond-like  shape,  and  vary  much  in 
size.  In  some  they  are  scarcely  seen — in  others  they  fill  up 
the  whole  fauces.  Their  inner  surface  is  free,  and  full  of 
foramina,  which  lead  into  the  mucous  follicles,  that  have 
been  mistaken  for  ulcerations.  Their  external  surface  is  cov- 
ered by  an  aponeurosis,  and  the  superior  constrictor  of  the 
pharynx.  They  are  very  subject  to  inflammation,  constitu- 
ting quinsy  or  tonsilitis,  and  to  chronic  enlargements  requir- 
ing extirpation.  Their  posterior  surface  corresponds  to  the 
angle  of  the  jaw,  and  they  are  in  relation  in  front  with  the 
facial  artery,  behind  with  the  internal  carotid,  and  on  the 
outer  side  with  the  external  carotid,  separated  by  the  supe- 
rior constrictor  of  the  pharynx,  and  some  cellular  tissue. 

The  structure  of  the  soft  palate  consists,  as  stated,  of  an 
aponeurosis,  muscles,  blood-vessels  and  nerves,  surrounded 
by  mucous  membrane. 

The  aponeurosis  is  a  strong,  dense,  and  fibrous  tissue, 
regarded  as  continuous  with  the  fibrous  structure  of  the 
septum  narium,  the  nasal  fossae  and  Eustachian  tube,  and 
constituting  the  frame  work  of  the  palate. 

The  Muscles  (Fig.  88)  of  the  soft  palate  are  five  pairs, 
i.  e.  the  levator  and  tensor  palati,  constrictor  istlimi  faucium, 
palato-pJiaryngeus ,  and  azygos  uvulae. 

Dissection. — Open  the  pharynx  from  behind,  by  separat- 
ing it  from  the  cervical  vertebras,  which  remove,  and  then 
take  off  the  mucous  membrane  of  the  palate,  when  its  mus- 
cles will  be  exposed. 

1.  Levator  palati  is  a  moderately  thick  and  round  mus- 
cle, and  arises  in  front  of  the  foramen  caroticum,  from  the 
extremity  of  the  petrous  bone,  and  back  of  the  Eustachian 
tube,  then  descends  by  the  side  of  the  posterior  nares,  and  is 
inserted  broad  into  the  soft  palate  as  far  as  its  median  line. 
Function,  to  raise  the  palate. 

2.  Tensor  palati,  or  circumflexus,  is  a  slender  muscle  upon 


SOFT  PALATE.  309 

the  outside  of  the  levator,  and  arises  fleshy  from  a  fossa  at 
the  root  of  the  internal  pterygoid  plate,  from  the  spinous 
process  of  the  sphenoid  bone,  and  front  part  of  the  Eustachian 
tube,  and  descends  along  the  pterygoid  plate,  becoming  a 
flat  tendon  as  it  reaches  the  hamulus,  round  which  it  turns. 
It  finally  expands  by  inserting  itself  into  the  aponeurosis 
of  the  palate,  and  according  to  some,  into  the  hard  ^palate 
also.  Function,  to  spread  the  palate. 

3.  Constrictor-isthmi-faucium  or  palato-glossus,  so  called 
from  its  constricting  or  closing  the  opening  to  the  fauces, 
occupies  the  anterior  half  arch  of  the  palate  and  is  in  front 
of  the  tonsil.     It  consists  of  a  small  bundle  of  fibres,  broader 
at   the  extremities  than  in  the   centre,  arises  from  the 
lower  surface  of  the  velum,  and  descends  to  be  inserted 
into  the  side  of  the  tongue.    Function,  to  raise  the  tongue, 
or  depress  the  palate,  and  close  the  fauces. 

4.  Palato-pharyngeus  occupies  the  posterior  half  arch  of 
the  palate,  and  arises,  in  common  with  its  fellow,  broad, 
from  the  lower  surface  of  the  velum,  and  passing  down- 
ward and  backward,  behind  the  tonsil,  is  inserted  into  the 
pharynx  at  its  side  and  back,  between  the  middle  and  lower 
constrictors,  and  into  the  border  of  the  thyroid  cartilage. 
Function,  to  raise  the  pharynx  as  deglutition  begins,  and 
to  depress  the  palate. 

5.  Azygos-uvulce  is  not,  as  its   name  implies,  a   single 
muscle,  but  a  pair  of  small  symmetrical  muscles,  placed 
side  by  side  on  the  median  line,  and  arising  from  the  poste- 
rior spine  of  the  palate  bone,  or  more  correctly  from  the 
aponeurosis,  continuous  with  the  spine.     It  descends  ver- 
tically to   constitute  the  greater  portion  of  the  uvulae. 
Function,  to  elevate  and  shorten  the  uvula. 

Blood-vessels. — The  arteries  of  the  soft  palate  are  the 
superior  and  inferior  palatine  branches  of  the  internal 
maxillary  and  facial.  The  veins  correspond  with  the 
arteries. 

The  nerves  are  the  palatine  branches  of  the  superior  max- 
illary of  the  fifth  pair,  coming  from  Meckel's  ganglion, 
also  branches  from  the  glosso-pharyngeal. 


310 


THE  TONGUE. 


THE  TONGUE. 

The  tongue  is  arranged  here  among  the  organs  of  degluti- 
tion, though  it  performs  a  variety  of  other  offices  equally 
important  in  connection  with  other  functions ;  as,  for  in- 
stance, it  is  concerned  in  prehension,  suction,  mastication, 
articulation,  playing  upon  wind  instruments,  and  is  the 
special  organ  of  taste. 

It  is  an  organ  of  motion \  its  great  bulk  consisting  of 
muscular  structure.  It  is  an  organ  of  sensation,  both 
special  and  general,  being  most  abundantly  supplied  with 
nerves ;  and  it  is  also  an  organ  of  secretion  ;  hence  the  im- 
portance of  this  body  considered  in  any  and  every  aspect. 
Its  situation  in  the  cavity  of  the  mouth,  and  within  the 
F,G.  59.  dental  arch,  in  the  state  of  rest, 

is  familiar  to  all.  It  is  kept  in 
its  position  by  ligaments  and 
muscles,  which  attach  it  to  the 
hyoid  bone,  the  styloid  pro- 
cesses and  the  lower  jaw.  It 
has,  however,  free  motion  at  its 
tip  and  sides.  The  posterior 
portion,  connecting  it  with  the 
os-hyoides,  is  called  its  base,  the 
middle  portion  the  body,  and  the 
anterior  part  the  tip.  It  has  two 
surfaces,  an  upper  and  lower; 
the  upper  is  called  the  dorsum 
of  the  tongue.  Its  size  is  very 
variable  in  different  individuals. 

TV 

but  is  always  in  proportion  to  the  curve  of  the  lower  jaw, 
and  never  fills  the  entire  cavity  of  the  mouth  when  the 
jaws  are  closed.  The  anterior  and  middle  part  is  hori- 

FIG.  89  represents  a  view  of  the  Upper  Surface  of  the  Tongue,  a  a  Poste- 
rior lateral  half  arches;  6  Epiglottis;  c  c  Mucous  membrane,  extending  from 
root  of  tongue  to  epiglottis;  d  Foramen  coecum  of  Morgagni;  e  Lenticular 
papillae;  /Papillae  filliformes;  g  Conical  papillae;  h  Point  of  tongue;  i  i  Fungi- 
form  papillae. 


THE  TONGUE.  311 

zontal,  while  the  posterior  makes  a  somewhat  vertical 
bend  down  to  the  os-hyoides.  This  account  of  its  direction 
is  true  when  the  tongue  is  kept  within  the  mouth,  hut 
when  it  is  protruded,  the  os-hyoides  rises,  and  the  whole  is 
then  on  nearly  the  same  horizontal  level. 

The  form  of  the  tongue  is  somewhat  of  an  ellipse.  Its 
upper  surface  or  dorsum  presents  a  very  rough  aspect  from 
numerous  eminences  called  papillae,  (papilla,  a  nipple.) 
These  papilla?  are  various  in  size,  and  have  received  dif- 
ferent names.  Those  at  the  hase,  arranged  in  the  shape 
of  the  letter  V,  are  the  papillce  maximce.  (Fig.  89.)  They 
are  ahout  nine  in  numher,  though  as  many  as  sixteen  and 
twenty  are  mentioned.  They  are  the  largest  in  size,  and 
present  two  rows,  forming  at  their  point  of  union  a  hlind 
opening  called  the  foramen  ccecum  of  Morgagni,  regarded  as 
the  receptacle  of  mucous  secretion  from  the  follicles.  These 
papillae  maximae  resemble  a  cone,  have  their  base  above 
and  free,  while  the  apex  is  below  and  fixed  in  a  cup-like 
cavity,  whence  they  are  also  called  calyciformes.  Within 
this  cup  a  fossa,  or  circular  trench,  is  seen  surrounding 
the  papilla,  from  which  also  the  name  of  circumvallatce, 
is  derived. 

The  papillce  mediae,  or  fungiformes,  the  next  in  size, 
are  found  irregularly  scattered  over  the  dorsum  of  the 
tongue,  and  some  are  seen  at  the  tip.  They  are  easily  re- 
cognized by  the  rounded  and  flattened  tops  resting  on  a 
narrow  pedicle,  and  having  a  direction  backwards. 

The  papilla!  villosce  or  conical,  and  the  filiform,  are  the 
smallest  and  most  numerous;  they  cover  the  whole  surface 
of  the  tongue,  being  scattered  among  all  the  others,  and 
are  most  abundant  at  the  tip. 

Blood-vessels  of  papillae. — The  microscope  of  Mr.  Nasmyth 
discovers  the  elements  of  the  papillae  to  consist  of  capillary 
vessels  and  loops  of  terminal  nervous  filaments,  connected  by 
an  areolo-fibrous  tissue.  The  capillaries  are  found  to  pro- 
ceed from  a  small  artery  running  through  the  centre  of  the 
papillae,  (Fig.  90,  B,)  and  then  ending  in  a  vein  which  re- 
turns along  the  course  of  the  artery.  A  variety  is  observed 


312 


THE   TONGUE. 


in  the  capillaries  of  the  different  papillae — in  those  of  the 
conical  papillae  of  the  foetus  a  coarse  net-work  is  observed, 
and  a  vascular  ring  surrounding  the  apex  of  each  papilla, 
giving  the  appearance  of  an  aperture.  In  the  filiform 
papillae,  the  capillaries  are  seen  as  a  single  loop,  (Fig.  90, 
A,)  while  in  the  papillae  maximae  or  calyciformes,  (Fig. 
90,  A?)  they  are  more  tortuous  and  of  the  plexus  form. 

Behind  the  papillae  maximae  some  eminences  are  ob- 
served having  the  same  arrangement  as  these  papillae.   They 

A  FIG.  90. 


were  formerly 
considered 
among  the  pa- 
pilla3,  but  are 

now  regarded  as  glands.  They  have  perforations  which 
are  visible  to  the  eye,  and  being  found  to  have  the  same 
structure  as  the  parotid,  are  considered  salivary  and  not 
mucous  glands. 

The  upper  surface  of  the  tongue  has  beneath  its  mucous 
coat  a  dense  membrane,  which  resembles  the  corium  of  the 
skin,  and  is  called  the  papillary  membrane  from  its  giving 
support  to  the  papillae.  In  some  instances  it  is  almost  as 
hard  as  cartilage.  It  is  divided  along  the  median  line  by  a 

FIG.  90,  A  represents  the  Papillae  on  a  part  of  the  surface  of  the  Tongue  of 
an  adult,  and  shows  the  manner  in  which  the  vessels  are  distributed.  «  Pa- 
pilloe  maximae  or  calyciforme.  6  6  The  groove  around  it.  c  Papillae  filiformes, 
or  thread-like  papill®.  d  Conical  papillae. 

FIG.  90,  B  represents  a  conical  Papilla,  having  at  its  extremity  a  An  aperture* 
The  distribution  of  its  vessels  is  also  seen. 


THE  TONGUE.  313 

raphe,  which  is  a  vertical  septum  of  ligamentous  matter, 
making  the  tongue  consist  of  two  equal  and  symmetrical 
parts. 

The  anterior  third  of  the  tongue  is  the  only  portion  free 
on  its  lower  surface,  all  the  rest  being  attached  by  mus- 
cles. On  this  surface  is  noticed,  along  its  middle,  a  furrow 
from  the  posterior  part  of  which  a  fold  of  mucous  mem- 
brane passes  to  the  posterior  surface  of  the  symphysis 
menti.  This  fold  is  called  the  frenum  linguce,  and  is  the 
part  concerned  in  the  "tongue-tie"  of  children,  where  it  is 
too  short  and  requires  division.  The  ranine  veins  are 
plainly  seen  on  each  side  of  this  furrow. 

Muscles  of  the  Tongue. — The  muscles  of  the  tongue  (Fig. 
87)  consist  of  four  pair,  which  have  been  given  at  the 
beginning  of  this  section,  except  one,  the  lingualis.  This 
is  the  intrinsic  muscle  of  the  tongue,  and  consists  of  a 
slender  fasciculus  of  fibres,  arising  indistinctly  among  the 
yellow  cellular  tissue  at  its  base,  and  passing  forward 
between  the  hyo-glossus  and  genio  Jiyo-glossus,  to  the  tip. 
Its  fibres  run  in  different  directions — being  transverse  and 
vertical,  as  well  as  longitudinal ;  hence  the  terms  transverse 
lingual,  and  vertical  lingual  muscles. 

The  superficial  fibres  of  this  muscle  are  closely  connected 
with  the  dense  papillary  membrane  or  corium,  which  is  a 
kind  of  skeleton  upon  which  they,  with  the  other  fibres, 
act  in  effecting  changes  both  in  the  form  and  density  of  the 
tongue.  Thus,  by  means  of  this  extensive  muscular  appara- 
tus, the  tongue  has  the  power  of  moving  in  every  possible 
direction — of  keeping  the  food  beneath  the  teeth,  and  of 
passing  it  from  the  mouth  into  the  pharynx — thereby  per- 
forming a  most  efficient  part  in  mastication,  as  well  as 
deglutition. 

Blood-vessels  of  the  Tongue9  (Figs.  T3,  91.) — The  arteries 
come  principally  from  the  lingual,  a  branch  of  the  external 
carotid,  and  injections  seem  to  show  that  the  arteries  be- 
longing to  either  half  of  the  tongue  advance  to  its  vertical 
septum,  and  then  stop — those  of  the  one  side  having  no 
anastomosis  with  those  of  the  other,  being  effectually  pre- 


314  THE  PHARYNX. 

vented  by  the  strong  ligamentous  barrier  placed  between. 
It  is  very  important,  in  the  excision  of  tumors,  or  other  op- 
erations on  one  side  of  the  tongue,  to  know  there  is  no  danger 
of  hemorrhage  from  the  vessels  of  the  opposite  side. 

Nerves,  (Fig.  91.)— The  nerves  of  the  tongue  come  from 
three  sources,  and  are  large.     1.  The  Gustatory  branch  of 
the  fifth  pair  goes  to  the  papilla,  and  gives  common  sensi- 
bility, and  is  also  supposed  to  be  the  special  sense  of  taste. 
FIG.  91.  2.  The  Lingual,  or  ninth 

pair,  goes  to  the  muscles 
and  gives  the  power  of  mo- 
tion. 3.  The  Gloss  o-pliaryn- 
geal  supplies  the  follicles, 
glands,  and  mucous  mem- 
brane of  the  tongue,  and 
is  regarded  as  a  compound 
nerve,  having  both  sensa- 
tion and  motion.  This 
nerve  connects  the  tongue 
with  the  pharynx  and  la- 
rynx. A  branch  of  the  fa- 
cial nerve  has  also  been  found  in  the  tongue,  but  was  seen 
only  on  one  side. 

THE  PHAKYNX. 

The  Pharynx  (Fig.  92)  is  situated  at  the  posterior  part 
of  the  mouth,  behind  the  nares,  in  front  of  the  cervical 
vertebrae,  and  below  the  base  of  the  skull,  extending  infe- 

FIG.  91  represents  the  side  of  the  Tongue,  with  the  relations  of  its  vessels  and 
nerves,  a  Hyoglossus  muscle.  6  c  Section  of  the  lower  jaw  at  its  symphysis. 
d  Genio-hyo-glossus.  e  Genio-hyoideus.  /Left  edge  of  mylo-hyoideus.  g  Com- 
mon carotid  artery,  and  its  division  into  external  and  internal,  h  Trunk  of 
superior  thyroid,  i  Lingual  artery,  j  Constrictor  medius  muscle,  k  Hori- 
zontal portion  of  lingual  artery.  /  Its  oblique  or  terminating  portion,  m  The 
ranine  artery,  n  Trunk  of  the  facial  artery,  o  The  three  posterior  branches 
of  external  carotid,  p  Trunk  of  ascending  pharyngeal.  r  Terminus  of  ex- 
ternal carotid  into  internal  maxillary,  and  temporal  arteries,  s  Gustatory 
branch  of  the  fifth  nerve,  *its  communication  with  the  lingual,  t  Glosso-pha- 
ryngeal  nerve.  M  Hypoglossal  or  ninth  nerve,  v  Duct  of  Wharton,  or  sub- 
maxillary  duct,  to  Sublingual  gland. 


THE  PHARYNX. 


315 


FIG.  92. 


riorly  to  the  fourth,  or  fifth  cervical  vertebra  behind  the 
lower  part  of  the  cricoid  cartilage,  where  it  ends  in  the 
ossophagus. 

Dissection. — Make  a  transverse  incision  at  the  lower  part 
of  the  neck,  through  the  trachea  and  oesophagus;  turn 
these  up  with  the  vessels  and  nerves,  to  the  base  of  the 
cranium,  and  then  detach  the  head  from  the  spine,  by 
disarticulating  at  the  atlas,  or, 
which  is  more  convenient,  by 
sawing  between  the  atlas  and 
dentata — now  stuff  the  pharynx 
with  curled  hair,  or  tow,  or  cot- 
ton, and  it  is  prepared  for  dis- 
playing its  muscles.  The  pha- 
rynx is  a  musculo-membranous 
sac  or  cavity,  somewhat  of  an 
oval  form,  attached  superiorly  to 
the  cuneiform  process  of  the  oc- 
cipital bone,  by  a  strong  apon- 
eurosis;  posteriorly,  to  the  deep 
muscles  of  the  neck  and  cervi- 
cal vertebrae,  by  a  loose  cellular  tissue;  anteriorly,  to  the 
internal  pterygoid  plate  of  the  sphenoid  bone,  hamular 
process,  posterior  part  of  the  upper  jaw,  and  mylo-hyoid 
ridge  of  the  lower  jaw — also  to  the  sides  of  the  tongue,  the 
cornua  of  the  os-hyoides,  and  the  sides  of  the  cricoid  and 
thyroid  cartilages.  There  is,  besides,  a  lateral  connection 
with  the  petrous  bone.  By  these  several  connections 
the  pharynx  is  kept  constantly  open,  and  its  walls  pre- 
vented from  falling  together. 

Structure. — The  pharynx  consists  pf  three  coats,  i.  e.  an 
outer  or  muscular,  a  middle  or  cellular,  and  an  inner  or 
mucous — in  addition  to  which,  it  abounds  in  blood-vessels 
and  nerves. 

FIG.  92  represents  a  view  of  the  Constrictors  of  the  Pharynx,  and  an  ante- 
rior view  of  the  Palate.  1  1  Superior  constrictor  of  the  pharynx.  2  2  Mid- 
dle constrictor.  3  3  Inferior  constrictor.  4  4  Levator  palati.  5  Uvula.  6  6 
Anterior  half  arch.  7  Circumflexus,  or  tensor  palati  muscle. 


316  THE  PHARYNX. 

The  muscles  (Fig.  92)  cover  the  back  -and  sides  of  the 
pharynx  in  one  uniform  membranous  sheet  or  layer,  and 
are  called  constrictors.  They  are  three  in  number,  the 
inferior,  middle,  and  superior  constrictors  of  the  pharynx. 
These  are  symmetrical  muscles,  lying  upon  either  side,  and 
connected  with  the  tendinous  line  or  raphe,  which  runs 
along  the  centre  of  the  back  part  of  the  pharynx. 

Constrictor  pliaryngis  inferior,  arises  from  the  inferior 
cornu,  and  posterior  ala  of  the  thyroid  cartilage,  and  from 
the  side  of  the  cricoid.  Its  fibres  radiate,  (some  ascending, 
and  others  transverse,)  to  be  inserted  into  the  raphe  on  the 
back  of  the  pharynx,  along  with  its  fellow.  The  superior 
fibres  overlap  the  middle  constrictor.  The  superior  la- 
ryngeal  nerve  passes  along  the  upper,  and  the  inferior 
laryngeal  beneath  the  lower  border  of  this  muscle. 

Constrictor  pliaryngis  medius — partly  covered  by  the  last, 
and  of  a  triangular  shape,  arises  from  the  appendix  and 
cornu  of  the  os-hyoides,  and  from  the  posterior  thyro-hyoid 
and  styloid  ligaments.  Its  fibres  ascend,  run  transversely, 
and  descend.  It  is  inserted  into  the  mesial  line,  and  by 
its  ascending  fibres,  into  the  cuneiform  process  of  the 
occipital  bone. 

Constrictor  pharyngis  superior  is  above  the  last,  and 
separated  from  it  by  the  stylo-pJiaryngeus  muscle,  and 
glosso-pharyngeal  nerve.  It  surrounds  the  upper  and  pos- 
terior part  of  the  pharynx,  and  arises  from  the  internal 
pterygoid  plate,  from  the  upper  jaw,  behind  the  last  molar 
tooth ;  from  the  pterygo  maxillary  ligament ;  from  the  side 
of  the  base  of  the  tongue,  and  from  the  posterior  portion 
of  the  mylo-hyoid  ridge.  From  this  extensive  origin,  the 
fibres  proceed  backwards  and  upwards,  and  are  inserted 
into  the  middle  line,  and  cuneiform  process  of  the  occipi- 
tal bone.  -  r*' 

Function. — The  constrictor  muscles  are  the  prime  agents 
in  deglutition,  and  conduct  the  food,  by  their  successive 
contractions,  from  the  pharynx  into  the  oesophagus. 

Stylo-pliaryngeus  is  a  slender  muscle  arising  from  the 
root  of  the  styloid  process.  It  passes  to  the  side  of  the 


THE  PHARYNX.  317 

pharynx,  between  the  upper  and  middle  constrictors,  and 
is  inserted  into  the  cornu  and  posterior  margin  of  the  thy- 
roid cartilage. 

Function. — To  raise,  dilate,  and  shorten  the  pharynx,  so 
as  to  receive  the  food.  It  will  also  elevate  the  larynx. 

The  middle  coat  consists  of  cellular  tissue,  called  the 
pharyngeal  aponeurosis,  which  is  stronger  along  the  mid- 
dle line  where  it  gives  attachment  to  the  constrictor  mus- 
cles, than  elsewhere,  and  is  the  connecting  structure  be- 
tween the  outer  or  muscular,  and  mucous  or  internal 
coat.  This  coat,  being  a  continuation  of  that  lining 
the  cavity  of  the  mouth,  will  be  considered  in  connection 
with  it. 

Cavity  of  the  Pharynx. — Dissection. — Make  an  incision 
through  the  middle  tendinous  line  on  the  back  part  of  the 
pharynx,  and  this  cavity  will  be  exposed.  In  front  will 
be  seen  the  velum  and  uvula,  and  opening  into  it  will  be 
noticed  seven  foramina;  at  its  upper  part  are  the  two  pos- 
terior nares,  on  each  side  of  these  are  the  Eustachian  tubes, 
in  front  is  the  isthmus  of  the  fauces,  and  below  we  see  the 
glottis,  and  the  commencement  of  the  oesophagus.  The 
Eustachian  tubes  are  found  at  the  posterior  part  of  the  in- 
ferior turbinated  bone,  and  as  just  stated,  on  each  side  of 
the  nares.  Their  mouth  is  circular,  and  large  enough  in 
most  cases  to  admit  the  end  of  the  little  finger.  They  lead 
to  the  ear,  and  conduct  the  air  from  the  pharynx  into  the 
cavity  of  the  tympanum.  Their  direction  is  upwards,  out- 
wards, and  backwards  to  the  tympanum,  occupying  in  their 
course  the  pterygoid  fossa,  and  having  in  two-thirds  of 
their  extent  a  thick  cartilaginous  structure,  the  balance 
being  composed  of  bone.  These  tubes  are  lined  by  the 
mucous  membrane  continued  from  the  pharynx,  and  when 
this  is  inflamed  they  become  thickened  and  obstructed,  this 
being  a  frequent  cause  of  deafness. 

Blood-vessels,  (Fig.  fS.) — The  arteries  supplying  the 
pharynx  are  the  superior  and  inferior  pharyngeal,  tHe  for- 
mer a  branch  of  the  internal  maxillary,  the  latter  a  branch 
of  the  external  carotid.  The  palatine  and  superior  thyroid 


318  THE  MOUTH. 

also  send  some  small  twigs.  The  veins,  after  forming  the 
pharyngeal  plexus  y  return  into  the  jugular  and  superior 
thyroid. 

Nerves. — The  nerves  of  the  pharynx  are  the  c/losso- 
pharyngealj  (Fig.  91,)  the  pharyngeal  "branch  of  the  par 
vagum,  all  belonging  to  the  eighth  pair,  and  branches 
from  the  superior  cervical  ganglion  of  the  sympathetic. 

SECTION    IX. 
THE  MOUTH. 

The  mouth,  (Fig.  93,)  situated  at  the  commencement  of 
the  digestive  tube,  is  composed  of  the  organs  of  prehension, 
FlG  93  mastication,     insaliva- 

tion,  and  part  of  those 
of  deglutition.  Hence  it 
is  evident  that  it  con- 
sists of  an  apparatus 
both  complicated  and 
various.  Having  con- 
sidered all  the  organs 
forming  the  mouth, 
successively  and  in  de- 
tail, it  now  seems 
proper  to  look  at  them 
for  a  moment  collect- 
ively in  their  several  relations  to  the  mouth  as  a  whole, 
and  in  their  united  and  harmonious  action  in  the  dis- 
charge of  the  various  functions  they  are  called  upon  to 
perform. 

The  cavity  of  the  mouth  is  bounded  superiorly  by  the 
palatine  processes  of  the  superior  maxillary  and  palate 
bones,  which  constitute  its  roof;  infer iorly  by  the  mylo- 

FIG.  93  represents  a  view  of  the  cavity  of  the  mouth,  a  Superior  lip  turned 
up.  6  Froenum  of  the  upper  lip.  c  Inferior  lip  turned  down,  d  Frsenum  of 
the  lower  lip.  e  e  Internal  surface  of  the  cheeks.  //  Point  where  the  duct 
of  steno  enters  the  mouth,  g  Roof  of  the  mouth,  h  Anterior  portion  of  the 
lateral  half  arches,  i  Posterior  portion  of  the  lateral  half  arches,  j  Velum 
pendulum  palati.  k  Tonsils.  I  Tongue. 


THE  MOUTH.  319 

hyoid  muscles,  forming  the  floor ;  anteriorly  by  the  lips ; 
posteriorly  by  the  soft  palate,  and  laterally  by  the  cheeks. 

Dissection. — To  expose  the  cavity  of  the  mouth,  make  an 
incision  through  its  angles,  carried  laterally  through  the 
cheeks,  dividing  the  buccinator,  masseter  and  insertion  of 
temporal  muscles ;  then,  in  sawing  through  the  lower  jaw 
on  one  side,  the  cavity  will  be  fully  laid  open  for  examin- 
ation. 

The  tongue,  teeth,  gums,  velum,  uvula,  tonsils,  and 
sublingual  glands,  are  some  of  the  contents  already  de- 
scribed of  this  cavity ;  the  whole  of  which,  as  well  as  the 
cavity  itself,  has  one  common  covering,  i.  e.  the  mucous 
membrane  of  the  mouth,  which  extends  into  the  pharynx, 
and  is  continuous  with  the  great  gastro-pulmonary  mucous 
membrane. 

The  mucous  membrane  of  the  mouth  and  pharynx  has 
already  been  considered  in  a  general  way  in  the  description 
of  this  elementary  tissue,  under  the  head  of  alphabet  of 
anatomy.  But  there  are  some  modifications  in  its  course, 
not  there  mentioned,  which  require  notice. 

It  will  be  recollected  that  mucous  membrane  is  usually 
soft,  pulpy,  easily  torn,  and  when  deprived  of  blood,  of  a 
pale,  grayish,  or  ashy  hue.  Now,  in  the  mouth  and  on  the 
lips  this  membrane  has  considerable  firmness,  and  pre- 
sents a  distinct  epithelium,  corresponding  to  the  cuticle  of 
the  skin.  The  nucleated  cells  of  which  this  epithelium  is 
at  first  composed,  as  they  advance  to  their  full  development 
gradually  lose  their  nuclei  and  present  the  form  of  scales, 
so  that  the  epithelium  of  the  mouth  is  called  squamous. 

As    the    mucous  FIG.  94. 

membrane  passes 
from  the  posterior 
surface  of  the  lips  to 
the  front  portions  of 
the  alveolar  pro- 
cesses  of  the  upper  and  lower  jaw,  it  is  folded  or  duplicated, 

Fio.  94  represents  a  Tiew  of  the  inner  side  of  the  Lips,  a  a  Ducts  of  Steno 
or  parotid  ducts.  6  6  Labial  glands. 


320 


THE  MOUTH. 


FIG.  95. 


and  these  folds  receive  the  name  of  frena  or  hridles  of  the 
lips.     Beneath  the  mucous  layer  of  the  lips  are  situated  the 

labial  glands.  These  consist  of 
small  spheroidal  granules.  Like 
the  parotid  and  the  rest  of  the 
salivary  glands,  they  lie  close  to 
each  other,  but  are  distinct,  and 
have  each  a  distinct  excretory 
duct,  and  open  by  a  separate  ori- 
fice on  the  posterior  surface  of  the 
lips.  Hence  they  are  regarded  as 
true  salivary,  and  not  mucous 
\a  glands,  (Fig.  94.) 

The  vascularity  of  the  lips,  as 
shown  under  the  microscope  of 
Mr.  Nasmyth,  is  exhibited  in 
Fig.  95.  A  represents  a  part  of 
the  mucous  membrane  on  the  in- 
ner side  of  the  upper  lip  of  a 
fetus,  minutely  injected,  mag- 
nified 40  diameters,  a  a  Papilla?, 
which  become  smaller  towards  the 
middle  of  the  figure,  b  Capilla- 
ries forming  a  plexus  with  small 
meshes,  c  The  capillary  plexus 
coarser,  the  meshes  larger  and 
corresponding  to  the  situation  of 
the  submucous  glands.  B  also 
magnified  40  diameters,  repre- 
sents a  portion  of  the  free  edge  of 
the  upper  lip  of  a  human  foetus, 
and  shows  the  manner  in  which 
the  capillaries  are  arranged  in  the 
papilla). 

The  mucous  membrane  in  pass- 
ing from  the  lips  over  the  alveolar 
processes,  to  get  behind  the  teeth,  undergoes  a  most  re- 
markable and  important  change,  being  transformed  into 
the  gums. 


THE  GUMS. 


321 


The  gums  are  distinguished  by  their  thickness,  by  their 
density,  being  almost  cartilaginous ;  by  their  intimate  ad- 
hesion with  the  periosteum  of  the  alveolar  processes  ;  and 
by  their  strong  attachment  to  the  necks'  of  the  teeth.  The 
vascularity  of  the  gums,  as  developed  by  Mr.  Nasmyth's 
microscope,  is  seen  in  the  annexed  figure. 

A  represents  the  B  lower  part  of  the  fig- 


papillae of  a  part 
of  the  gum  of  an 
adult,  minutely  in- 
jected, magnified 
38  diameters,  and 
shows  the  tortuous 
course  of  the  capil- 
lary vessels. 

B  represents  a 
part  of  the  gum 
and  adjacent  mu- 
cous membrane  of 
the  human  fcetus, 
magnified  100  di- 
ameters. In  the 

FIG.  96.        A 


ure  are  seen  the  plex- 
uses formed  by  the 
larger  vessels ;  and  in 
the  upper  part  are 
seen  the  papillae. 
c 


C  shows  a  portion  of  the  mucous  membrane  of  the  gum 
and  palate  of  the  human  fcetus,  minutely  injected  and  mag- 
nified *75  diameters.  The  deeper  vessels  are  the  largest, 
and  the  spaces  in  the  superficial  plexus  correspond  to  the 
situation  of  the  submucous  glands. 


322  ALVEOLO-DENTAL-PERIOSTEUM. 

The  gum  is  traced  from  the  neck  of  the  tooth  into  the  al- 
veolar cavity,  as  continuous  with,  and  constituting  the 
alveolo-dental  periosteum.  In  the  infant  state  the  gums 
present  on  their  superior  edge  a  dense,  white,  cartilaginous 
ridge,  which  becomes  thinner  and  thinner  as  the  period 
of  eruption  approaches.  The  failure  to  undergo  this  thin- 
ning process  is  the  not  unfrequent  cause  of  great  irritation 
and  even  of  convulsions  in  teething.  In  the  tissue  of  the 
gums,  mucous  follicles  are  found,  which  have  been  mistaken 
for  glands  furnishing  the  tartar,  and  have  hence  been 
called  tartar  glands.  But  it  is  now  settled  that  the  tartar 
is  simply  a  deposit  of  calcareous  matter  from  the  saliva. 

Alveolo-dental  periosteum. — This  membrane  is  fibrous  in 
structure — is  attached  to  the  necks  of  the  teeth- — lines  the 
alveolar  cavities — covers  the  roots — is  connected  to  the 
blood-vessels  and  nerves,  where  they  enter  the  apices  of 
the  teeth,  and  is  believed  by  Mr.  Bell,  to  enter  the  cavities 
of  the  teeth,  lining  their  interior  walls,  and  being  contin- 
uous with,  or  the  same  as  that  of  the  pulp. 

It  has  just  been  stated  that  this  membrane  is  believed 
to  be  continuous  with  that  of  the  gums.  Others  think 
that  the  sac  containing  the  pulp,  which  consists  of  two 
coats,  after  the  eruption  of  the  teeth,  forms  (especially  the 
outer  coat)  this  alveolo-dental  periosteum;  while  Mr.  Bell, 
on  the  other  hand,  believes  that  the  sac  is  entirely  ab- 
sorbed, and  that  this  membrane  is  the  same  as  the  perios- 
teum, covering  the  superior  and  inferior  maxillary  bones, 
continued  into  the  alveolar  cavities,  and  from  thence  re- 
flected on  the  roots  of  the  teeth.  This  membrane  is 
important  in  maintaining  the  teeth  in  their  sockets. 

In  tracing  the  mucous  membrane  from  the  gums,  we 
next  find  it  covering  the  roof  of  the  mouth,  the  soft  palate, 
the  interior  of  the  cheeks,  the  tongue,  and  thence  follow 
it  into  the  pharynx. 

The  mucous  membrane,  covering  the  roof  of  the  mouth , 
is  characterized  by  the  thickness  of  its  epithelium,  the 
density  of  its  chorion,  its  strong  adhesion  to  the  bone,  its 
whitish  color;  and  the  numerous  orifices  noticed  in  it, 


MUCOUS  MEMBRANE  OF  THE  MOUTH.         323 

especially  at  its  back  part.  On  the  median  line  of  the  pal- 
atine arch,  the  mucous  membrane  is  most  strongly  attached 
to  the  periosteum — while  on  either  side  of  this  line  there 
is  interposed  a  thick  layer  consisting  of  glands.  These 
glands  are  found  to  be  sometimes  disposed  in  regular  rows 
over  the  palatine  arch,  and  from  their  being  like  the  labial 
and  parotid,  are  called  the  palatine  salivary  glands.  They 
are  in  greater  numbers  behind  than  in  front,  and  open  by 
many  orifices  which  are  visible  to  the  eye. 

The  mucous  membrane,  lining  the  cheeks,  is  a  continua- 
tion of  that  belonging  to  the  lips,  already  described.  There 
is  also,  beneath  it,  a  layer  of  glands  of  the  salivary  order, 
which  cause  projections  on  its  surface,  and  are  called  the 
salivary  buccal  glands.  They  are  precisely  like  the  labial, 
though  smaller,  and  open  by  distinct  orifices.  Two  of  these 
glands,  from  not  being  situated  directly  beneath  the  mem- 
brane, but  placed  between  the  buccinator  and  masseter 
muscles,  are  called  the  molar  glands.  Their  ducts  open 
opposite  the  last  molar  tooth. 

The  mucous  membrane  of  the  soft  palate  is  remarkable 
for  its  upper  or  nasal  surface  presenting  the  columnar 
arrangement  in  its  epithelium,  while  the  lower  or  lingual 
surface  has  the  squamous  form  of  the  mouth. 

The  mucous  membrane  of  the  pharynx  has  a  reddish 
appearance,  and  is  characterized  by  its  density  and  close 
adhesion  to  the  periosteum  upon  the  basilar  process.  It 
forms  a  rim  around  the  mouth  of  the  Eustachian  tube,  and 
becomes  thinner  as  it  traverses  the  tube  towards  the  cavity 
of  the  tympanum. 

This  relation  established  between  the  nose  and  throat, 
and  the  Eustachian  tubes,  by  the  continuity  of  the  same 
mucous  membrane  into  these  several  parts,  is  regarded  as 
the  cause  of  that  deafness  which  occurs  from  obstruction 
in  these  tubes  during  coryza  and  chronic  sore  throat. 

Blood-vessels  of  the  Houtli  and  Pharynx,  (Fig.  73.) — The 
internal  maxillary,  facial,  lingual,  and  pharyngeal  arteries, 
all  branches  of  the  external  carotid,  are  the  principal  sources 
whence  the  mouth  and  pharynx,  with  all  their  organs,  are 


324  ORGANS   OF  EXPRESSION. 

supplied.  They  have  been  already  detailed.  The  veins 
have  corresponding  names  and  situation  with  the  arteries, 
and  terminate  in  the  jugular. 

The  nerves  (Fig.  74,  91,  9<T)  supplying  the  mouth  and 
pharynx  come  from  the  fifth,  the  seventh,  eighth,  and 
ninth  pair  of  the  cerebral  nerves,  and  from  the  sympa- 
thetic system. 


CHAPTER  III. 

ORGANS    OF    EXPRESSION. 

THESE  comprise  the  muscles  concerned  in  giving  expres- 
sion to  the  various  passions,  which  are  chiefly  the  occipito 
frontalis,  corrugator  supercilii,  pyramidalis  nasi,  compressor- 
nasij  and  orbicularis  palpebrarum,  (Fig.  55.)  The  facial 
nerve  (Fig.  97)  must  also  be  included  in  the  organs  of 
expression,  as  it  is  the  motive  power  of  the  muscles. 

Occipito-frontalis. — Dissection. — Commence  an  incision 
from  the  root  of  the  nose,  and  carry  it  through  the  integu- 
ment, along  the  median  line  of  the  cranium,  as  far  back  as 
the  tuberosity  of  the  occipital  bone.  Make  a  second  in- 
cision parallel  with,  and  about  half  an  inch  above  the 
eyebrow,  and  connect  it  with  the  first.  Make  a  third 
incision  from  the  posterior  extremity  of  the  first,  upon 
either  side  of  the  occipital  protuberance,  along  the  superior 
transverse  ridge  of  this  bone.  Commence  dissecting  off  the 
integuments  at  the  transverse  incision,  and  this  muscle  will 
be*  exposed.  The  adhesion  between  this  muscle  and  the 
scalp  is  very  close,  and  this,  added  to  the  paleness  of  its 
fibres*  makes  the  dissection  both  difficult  and  tedious,  re- 
quiring caution  and  perseverance  to  succeed.  The  scalp 
being  removed,  this  muscle  is  seen  to  consist  of  four  fleshy  bel- 
lies— two  anterior  covering  the  forehead,  and  two  posterior 
investing  the  occiput,  with  an  intervening  and  expanded 
aponeurotic  structure,  covering  the  superior  and  lateral  por- 
tions of  the  cranium.  It  arises  by  two  fleshy  bellies,  with  ten- 
dinous fibres,  from  the  superior  transverse  ridge  of  the 


ORGANS  OF  EXPRESSION.  325 

occipital  bone,  and  from  the  mastoid  process  of  the  tempo- 
ral. The  fibres  ascend,  and  soon  terminate  in  one  broad 
sheet  of  tendon,  called  the  epicranial  aponeurosis,  which 
spreads  over  the  superior  and  lateral  parts  of  the  cranium, 
as  far  forward  as  the  coronal  suture,  where  it  again 
becomes  fleshy,  forming  the  two  anterior  bellies  which  are 
inserted  into  the  skin  of  the  eyebrow,  and  mingle  their 
fibres  with  those  of  the  corrugator  supercilii,  and  orbicu- 
laris  palpebrarum  muscles. 

This  muscle  is  regarded  by  some  as  a  digastric  muscle — 
by  others,  as  quadriceps — two  frontal  and  two  occipital 
muscles,  having,  in  either  case,  the  central  aponeurosis  as 
their  common  point  of  insertion.  There  extends  down 
from  this  muscle  a  fleshy  slip  along  the  nasal  bones,  which 
is  attached  to  the  internal  angular  process  of  the  frontal 
bone.  It  is  considered  as  a  distinct  muscle,  and  called  the 
pyramidalis  nasi,  orfronto  nasalis. 

This  muscle  is  loosely  connected  to  the  cranium,  but 
closely  to  the  scalp.  Function — to  elevate  the  eye-brows  and 
throw  the  forehead  into  transverse  wrinkles ;  to  raise* the 
upper  lids  and  expose  the  ball  of  the  eye  as  in  staring ;  and 
to  draw  the  scalp  either  backward  or  forward  as  the  ante- 
rior or  posterior  bellies  become  the  fixed  points  of  action. 

Corrugator  Supercilii,  (Fig.  55.) — Dissection. — Turn  down 
the  integument  of  the  eyebrow  from  the  transverse  incis- 
ion of  the  frontal  muscle,  beneath  which  this  muscle  will 
be  seen.  It  arises  from  the  internal  angular  process  of  the 
os-frontis,  and  proceeds  upward  and  outward  between 
the  occipito  frontalis,  and  orbicularis  palpebrarum,  to  be 
inserted  into  these  and  the  middle  of  the  eyebrow. 

This  muscle  is  said  to  be  peculiar  to  man  alone,  and 
to  be  found  in  none  of  the  inferior  animals.  It  is  con- 
nected largely  with  expression,  and  the  exhibition  of  men- 
tal operations. 

Function. — To  draw  the  eye-brows  towards  each  other 
as  in  frowning,  and  to  throw  the  forehead  into  vertical 
wrinkles. 

Compressor  nasi,  (Fig.  55,)  a  small,  thin,  triangular 


326  ORGANS  OP  EXPRESSION. 

muscle,  arising  from  the  canine  fossa  of  the  upper  maxilla, 
and  then  spreading  over  the  ala  nasi,  is  inserted  along 
with  its  fellow  upon  the  dorsum  of  the  nose,  by  a  thin 
aponeurosis. 

function. — It  can  either  compress  or  dilate  the  nostril, 
as  one  or  the  other  of  its  attachments  becomes  the  fixed 
point  of  action.  In  panting,  as  in  violent  respiration  after 
running,  as  seen  in  the  horse,  this  muscle  becomes  a  pow- 
erful dilator,  and  has  received  the  name  of  the  dilator  na-si. 

Orbicularis  palpebrarum,  (Fig.  55.) — Dissection. — The 
same  incision  for  exposing  the  corrugator  supercilii,  being 
carried  round  the  lower  margin  of  the  orbit  to  the  inner 
canthus  of  the  eye,  also  exposes  this  muscle  as  well  as  the 
compressor  nasi. 

It  arises  fleshy  from  the  internal  angular  process  of  the 
os  frontis,  and  upper  edge  of  the  tendo  oculi — its  fibres  then 
proceed  upward  and  outward,  broad  and  thin,  along  the 
upper  edge  of  the  orbit  and  tarsal  cartilage,  describing 
curves  in  their  course  to  the  external  commissure  of  the 
eyelids ;  from  this  it  is  continued  round  in  similar  curves 
upon  the  lower  edge  of  the  orbit  and  lower  eyelid  to  the 
internal  canthus  of  the  eye,  where  it  is  inserted  into  the 
nasal  process  of  the  superior  maxilla,  the  inner  third  of 
the  edge  of  the  orbit,  and  the  lower  edge  of  the  tendo  oculi. 
The  tendo  oculi  or  tendo  palpebrarum  is  a  short,  horizontal 
tendon,  about  a  quarter  of  an  inch  in  length,  attached  to 
the  superior  end  of  the  nasal  process  of  the  upper  maxilla, 
and  extending  thence  transversely  to  the  inner  canthus  of 
the  eye,  where  it  is  distinctly  felt.  At  this  point  it  forks ; 
the  divided  portions  enclose  the  caruncula  lachrymalis  and 
are  connected  with  the  tarsal  cartilages  and  lachrymal 
duct.  This  tendon  also  passes  across  the  lachrymal  sac, 
and  sends  off  a  strong  aponeurosis  which  covers  its  anterior 
surface.* 

Function. — To  close  the  eyelids,  which  is  done  by  the 
fibres  of  this  muscle  being  drawn  in  a  straight  line. 

*The  palpebral  portion  of  this  muscle,  running  along  the  margin  of  the  eye- 
lids, is  called  the  Ciliaris  Muscle. 


NERVE  OF  EXPRESSION.  327 


CONJOINT  ACTION  OP  THESE  MUSCLES  IN  EXPRESSION. 

If  the  orbicularis  palpebrarum  and  pijramidales  nasi  act 
together,  the  expression  is  "  heavy  and  lowering."  If  these 
yield  to  the  influence  of  the  frontal,  the  eyehrow  is  arched 
and  the  expression  is  "cheerful  and  inquiring."  If  the 
corrugator  supercilii  act,  it  is  said  by  Mr.  C.  Bell  to  indi- 
cate "  more  or  less  of  mental  anguish,  or  painful  exercise 
of  thought."  If  it  combine  its  action  with  the  frontal  por- 
tion of  the  occipito-frontalis,  the  eyebrow  is  drawn  upwards, 
and  the  forehead  wrinkled,  giving  an  expression  more  of 
"weak  anxiety  and  querulousness." 

The  compressor  nasi,  in  conjunction  with  the  levator 
labii  superioris  alceque  nasi,  and  depressor  nasi,  by  com- 
pressing, depressing  and  expanding  the  nostrils,  indicate 
"  general  excitement  and  animal  activity,  and  give  spirit  to 
the  whole  countenance." 

It  may  be  proper  to  notice  in  this  connection  that  all  the 
muscles  attached  to  the  mouth  are  also  muscles  of  expres- 
sion, though  they  have  been  described  in  another  place 
under  the  head  of  prehension.  We  will  only  notice,  further, 
in  reference  to  their  relations  with  expression,  that  when 
the  orbicidaris  oris,  or  sphincter  muscle  of  the  mouth,  con- 
tracts, while  the  lateral,  or  zygomatic  muscles  are  in  action, 
there  is  "a  painful  and  bitter  expression."  If,  on  the  con- 
trary, the  orbicularis  of  the  mouth  be  relaxed,  while  the 
orbiculares  of  the  eyelids  are  contracted,  then,  by  the  action 
of  the  lateral  muscles,  there  is  produced  a  "  cheerful  and 
smiling  expression  of  the  countenance." 

The  depressor  anguli  oris  is  said  to  be,  like  the  corrugator 
supercilii,  peculiar  to  man ;  and  when  it  combines  its  ac- 
tion with  the  levator  menti  produces  "the  most  contempt- 
uous and  proud  expression." 

The  eye  is  also  full  of  expression,  and  so  are  other  portions 
of  the  body,  all  of  which  will  be  examined  in  their  appro- 
priate places. 

Nerve  of  Expression,  Fig.  97,  (the  facial  nerve,)  called  also 
the  portio-dura  of  the  seventh  pair,  is  the  great  nerve  of 


328 


NERVE   OF   EXPRESSION. 


FIG.  &7. 


expression  and  motion  to  the  face,  and  is  one  of  the  respi- 
ratory nerves  of  Sir  Charles  Bell.  It  arises  from  what  is 
termed  by  this  latter  gentleman,  the  respiratory  tract,  and 

from  that  particular  por- 
tion of  this  tract,  lying 
between  the  corpus  olivare 
and  corpus  restiforme,  at 
the  upper  part  of  the 
medulla  oblongata,  and 
near  the  pons,  whence  its 
fibres  are  traced  into  the 
corpus  restiforme.  It  is 
smaller  than  the  auditory 
nerve,  and  anterior  and 
superior  to  it  in  the  mea- 
tus  auditorius  internus, 
where  they  both  enter, 
and  where  they  inter- 
change connecting  filaments.  After  the  facial  nerve  tra- 
verses the  auditory  meatus,  at  the  bottom  of  this  latter,  it 
enters  the  aqueduct  of  Fallopius — pursues  the  course  of  this 
canal,  which  is  between  the  cochlea  and  vestibule,  and 
behind  the  tympanum — proceeds,  first,  horizontally  back- 
ward, then  outward  above  the  fenestra  ovalis,  and  de- 
scends along  the  inner  wall  of  the  tympanum,  to  the  stylo 
mastoid  foramen,  at  which  it  emerges.  From  this  point  it 
proceeds  forward  in  the  substance  of  the  parotid  gland, 
crossing  the  external  carotid  artery,  and  external  jugular 
vein,  to  the  ramus  of  the  lower  jaw,  behind  which  it 
divides  into  two  branches  called  the  temporo-facial,  and 
cervico-facial.  Opposite  to  the  hiatus  Fallopii,  the  Vidian 

FIG.  97  represents  the  Facial  nerve,  or  Portio-dura  of  the  seventh  pair,  a 
Trunk  of  the  facial  nerve,  6  Ascending  branch,  c  Descending  branch,  d 
Posterior  auricular  branch,  e  e  Temporal  branches.  //  Malar  branches- 
g  g  Inferior  maxillary  branches,  h  Occipital  nerve,  i  Terminal  branches  of 
the  inferior  dental,  j  Terminal  branches  of  infra  orbital,  k  k  Supra  orbital 
nerve  and  branches.  I  Orbicularis  oris  muscle,  in  Zygomaticus  major,  n 
Zygomaticus  minor,  o  Levator  labii  superioris  alceque  nasi.  p  Orbicularis 
palpebrarum.  q  Depressor  anguli  oris. 


NERVE  OF  EXPRESSION.  329 

nerve,  from  the  ganglion  of  Meckel,  joins  the  facial.  At 
this  point  of  junction  there  is  seen  a  gangliform  expansion, 
receiving  filaments  from  the  sympathetic,  and  from  the 
otic  ganglion  of  Arnold.  Here  the  Vidian  nerve  separates 
from  the  facial,  and  enters  the  cavity  of  the  tympanum  at 
its  superior  and  posterior  portion,  becoming,  at  this  point, 
the  chorda  tympani,  which  crosses  the  cavity  of  the  tympa- 
num obliquely  forward  and  downward,  between  the  han- 
dle of  the  malleus  and  long  leg  of  the  incus,  escapes  through 
a  foramen  on  the  inner  side  of  the  fissure  of  Glasser,  and 
joins  the  gustatory  nerve,  at  an  acute  angle,  between  the 
pterygoid  muscles.  At  the  angle  of  the  jaw,  it  leaves  the 
trunk  of  the  gustatory,  and  goes  to  the  submaxillary  gan- 
glion, where  it  terminates.  The  chorda  tympani  has  been 
considered,  by  some  anatomists,  a  branch  of  the  facial;  but 
Mr.  Jno.  Hunter  appears  to  have  satisfactorily  demonstrated 
the  Vidian  to  be  the  recurrent  branch  of  the  second  division 
of  the  fifth  pair,  and  consequently  a  nerve  of  sensation. 
From  the  circuitous  route  of  the  Vidian,  it  is  seen  to  estab- 
lish several  very  interesting  connections.  It  connects  the 
ganglion  of  Meckel  with  the  superior  cervical  ganglia,  by 
filaments  which  unite  with  sympathetic  filaments  in  the 
cavernous  sinus,  before  entering  the  hiatus  Fallopii;  unites 
Meckel's  ganglion  with  the  submaxillary  ganglion — con- 
nects the  superior  and  inferior  maxillary  nerves  together, 
and  further  unites  both  these  with  the  facial. 

The  branches  of  the  facial  are,  1.  Tympanic,  one  or  two 
small  filaments  in  the  cavity  of  the  tympanum,  to  supply 
the  stapcdius  and  tensor  tympani  muscles.  2.  Three 
branches,  just  as  it  emerges  from  the  stylo-mastoid  fora- 
men, the  posterior  auricular,  the  stylo-hyoid,  and  digas- 
tric, supplying  the  back  of  the  ear,  the  stylo-hyoid,  and 
digastric  muscles.  3.  In  the  substance  of  the  parotid, 
the  temporo-facial  and  cervico-facial,  terminating  branches 
of  this  nerve,  which  send  off  numerous  filaments  that  con- 
nect and  interlace,  so  as  to  form  a  plexus,  called  the 
parotidean  plexus,  or  pes  anserinus.  The  temporo-facial 
ascends  over  the  neck  of  the  lower  jaw,  to  be  distributed 


330  ORGANS  OF  SENSE. 

over  the  temple  and  upper  portions  of  the  face,  by  branches 
termed  temporal,  malar,  and  buccal,  which  anastomose 
with  the  auricular  branch  of  the  inferior  maxillary,  the 
supra  orbital,  and  infra  orbital  nerves. 

The  cervico-facial  descends,  supplying  the  lower  portions 
of  the  face,  and  upper  portions  of  the  neck,  by  branches 
called  the  maxillary,  submaxillary,  and  cervical,  which 
communicate  with  the  mental  nerve  and  ascending  fila- 
ments of  the  cervical  plexus.* 

Blood-vessels. — The  arteries  supplying  the  organs  of  ex- 
pression, come  from  the  facial,  transverse  facial,  occipital, 
temporal,  and  internal  maxillary  of  the  external  carotid, 
and  from  the  ophthalmic  of  the  internal  carotid  artery, 
(Fig.  'TS.)  The  veins  correspond  to  the  arteries — those  of 
the  external  carotid  go  to  the  jugulars — those  of  the  inter- 
nal carotid,  to  the  cavernous  sinus. 


CHAPTEK  IV. 

ORGANS    OF    SENSE. 

SENSATION  is  defined  to  be  a  "  change  in  the  condition  of 
the  mind,  by  which  we  become  aware  of  an  impression 
made  upon  some  part  of  the  body,"  or  it  is  styled  the  "con- 
sciousness of  an  impression." 

Organs  of  sense  are  the  instruments  of  receiving  the  im- 
pression, through  which  a  corresponding  change  in  the 

*  Another  view  of  this  complex  nervous  arrangement  may  be  taken.  Accord- 
ing to  many  excellent  observers,  there  are  three  divisions  of  the  seventh 
nerve,  instead  of  two.  The  portio  mollis,  or  auditory,  and  the  portio  dura,  or 
facial,  have  lying  between  them,  from  their  very  origin,  a  set  of  filaments 
which  can  be  dissected  from  them,  and  shown  to  unite  in  a  nervous  trunk  of  a 
reddish  color,  strongly  contrasting  with  the  pure  white  tint  of  the  facial.  This 
portio  intermedia,  as  it  has  been  called,  can  be  traced  closely  connected  with 
the  facial,  following  it  into  the  aqueduct  of  Fallopius,  and  sending  filaments  to 
both  it  and  the  auditory,  and  finally  losing  itself  in  the  geniculate  ganglion, 
called,  also,  int umescentia gangliformis,  or genuformis.  This  geniculate  ganglion 
also  receives  the  two  petrosal  nerves,  one  of  which  is  a  branch  of  the  Vidian, 


THE  EYE.  331 

mind,  called  sensation,  is  effected.  The  organs  of  sense  are 
divided  into  external  and  internal.  The  former  comprise 
the  eye,  the  ear,  the  tongue,  the  nose,  and  the  skin,  per- 
forming the  functions  of  seeing,  hearing,  tasting,  smell- 
ing, and  touch.  The  latter  division  of  internal  sensation 
includes  the  brain  and  nervous  system. 

SECTION  I. 

THE  EYE. 

The  organ  of  vision  consists  of  the  eye  proper  or  ball, 
and  of  the  appendages  of  the  eye,  or  tutamina  oculi. 

The  ball  or  globe  of  the  eye  furnishes  an  example  of  the 
most  perfect  of  optic  instruments,  and  the  most  surprising 
adaptation  in  all  its  parts,  for  the  purposes  of  vision.  It,  in 
fact,  combines  the  properties  of  both  the  microscope  and 
telescope,  being  constructed  to  view  objects  both  near  and 
at  a  distance,  and  having  special  relation  to  the  stimulus 
of  light.  , 

The  eye  is  situated  in  front  of  the  bony  orbit — resting 
upon  an  elastic  cushion  of  fat,  which  allows  it  great  mo- 
bility, and  which,  from  its  quantity,  whether  great  or 
small,  will  Cause  a  proportionate  projection  or  retraction  ; 
so  as  to  give  the  appearance  of  either  large  or  small 
eyes,  though,  in  fact,  the  eye  may  not  vary  absolutely 
in  size. 

It  is  surrounded  and  retained  in  its  situation  by  muscles, 
vessels,  nerves,  the  conjunctive  membrane  and  the  eyelids. 
Its  form  is  nearly  a  sphere;  the  antero-posterior  diameter 
being  somewhat  the  longest  on  account  of  the  projection 

and  the  other  is  connected  with  the  otic  ganglion  and  with  Jacobson's  nerve. 
Regarding  this  ganglion  as  a  nervous  centre,  then,  we  have,  entering  into  it, 
filaments  from  the  seventh,  eighth,  fifth,  and  sympathetic  nerves.  The  chorda 
tympani  springs  from  it,  crosses  the  tympanum,  as  already  described,  lies  close 
to  the  gustatory,  and  finally  is,  according  to  some  anatomists,  distributed  to  the 
lingualis  muscle  ;  according  to  others,  connected  with  the  submaxillary  gan- 
glion. We  have  already  alluded  to  this  complex  relationship,  and  have  called 
attention  to  the  opinion  of  Malaguti,  that  this  portio  intermedia  is  a  sympathetic 
nerve,  entering  the  substance  of  the  brain,  and  uniting  a  very  great  diversity 
of  organs  by  its  numerous  connections. 


332 


THE  EYE. 


B 


FlG-  98«         A  of  the  cornea 

and  measur- 
ing about  one 
inch.  The 
axes  of  the 
eyes  are  par- 
allel to  each 
other,  "but  not 
to  that  of  the 
bony  orbit. 

The    eye 
is    a    hollow 
sphere    com- 
posed  of   a 
membranous   case,  and 
four  refractive  lenses  or 
media    of  light.     The 
case    consists   of   three 
coats  or  membranes,  an 
outer,  middle  and  inner, 
called  the  sclerotic,  cho- 
roid,  and  retina. 

Tunica  Sclerotica, 
(Fig.  98,  A,)  (twtypoj, 
hard.) — Dissection. — Clean  the  ball  of  all  its  attachments, 
which  is  best  done  with  the  scissors,  while  the  eye  rests  in 
a  shallow  dish  of  water. 

This  membrane  forms  the  whole  of  the  outer  coat  of  the 
eye,  except  its  front  part,  which  receives  the  cornea.  Its 

FIG.  98,  A  represents  a  section  of  the  Eyeball.  1  Upper  lid.  2  2  Meibo- 
mian  glands.  3  Reflection  of  tunica  conjunctiva.  4  Cornea.  5  Anterior 
chamber  of  the  aqueous  humor.  6  Pupil.  7  Iris.  8  Crystalline  lens.  9 
Ciliary  processes.  11  Canal  of  fontana.  12  Canal  of  petit.  13  Section  of  the 
vitreous  humor.  14  Central  artery  of  the  retina,  passing  through  the  vitreous 
humor.  15  Optic  nerve,  a  Sclerotic  coat,  b  Choroid.  c  Membrane  of 
Jacobs,  d  Ptetina.  e  Hyaloid  membrane. 

FIG.  98,  B  represents  the  Choroid  coat,  or  second  tunic  of  the  Eye.  a 
Choroid.  6  b  Ciliary  nerves,  c  Long  ciliary  artery,  d  Ciliary  ligament,  e 
Iris,  showing  its  two  sets  of  fibres — the  circular  and  radiating.  /  Pupil. 


THE  EYE.  333 

extent  consequently  readies  from  the  optic  nerve  to  the  cir- 
cumference of  the  cornea.  It  is  a  pearly  white,  dense,  very 
strong,  inelastic  fibrous  membrane,  designed  to  preserve 
the  shape  of  the  eye,  and  protect  the  delicate  structures 
within. 

The  external  surface  is  perforated  round  the  optic  nerve, 
which  enters  at  the  posterior  part,  with  many  small  fora- 
mina for  the  passage  of  the  ciliary  vessels  and  nerves.  It  is 
covered  by  the  tunica  conjunctiva,  with  which  it  is  loosely 
connected  by  cellular  tissue,  and  gives  insertion  to  several 
muscles.  Divide  this  membrane  circularly  from  its  centre 
and  reflect  it  forward  towards  the  cornea,  and  backward 
to  the  optic  nerve,  carefully  raising  it  from  the  choroid,  so 
that  its  internal  surface  and  density  can  be  examined. 

The  internal  surface  of  the  sclerotic,  presents  a  brown 
color,  and  is  attached  by  delicate  filamentous  tissue,  and 
by  the  ciliary  vessels  and  nerves  to  the  choroid,  which 
gives  this  surface  a  rough  appearance,  but  when  these  con- 
nections are  removed,  which  can  be  readily  done,  it  pre- 
sents a  smooth  and  glossy  surface,  from  which  it  is  said  a 
serous  layer  can  be  dissected.  This  surface  also  exhibits 
the  openings  for  the  ciliary  vessels  and  nerves  which  enter 
externally. 

The  density  of  this  coat  is  greatest  behind,  and  becomes 
gradually  thinner  as  it  approaches  the  centre  ;  which, 
however,  in  front  of  this  is  again  increased  in  thickness  by 
the  tendinous  addition  of  the  recti  muscles. 

It  is  perforated  behind  by  the  optic  nerve,  about  one  line 
and  a  half  internal  to  the  antero  posterior  axis.  The  por- 
tion of  the  sclerotic  where  the  optic  nerve  enters,  presents  a 
cribriform  appearance,  and  is  called  lamina-cribrosa,  having 
its  edges  beveled,  and  containing  a  groove  for  the  recep- 
tion of  the  cornea.  The  outer  layer  of  the  sclerotic  over- 
laps the  cornea,  and  the  union  of  the  two  is  most  intimate. 

Structure. — The  sclerotic  is  regarded  as  one  of  the  strong- 
est fibrous  membranes  of  the  body,  having  its  fibres  inter- 
lacing in  every  direction,  and  not  capable  of  being  separated 
into  any  true  laminae.  It  is  continuous  with  the  sheath  of 


334  THE   EYE. 

the  optic  nerve,  which,  is  derived  from  the  dura  mater.  In 
the  normal  state  it  possesses  little  sensibility,  though  when 
attacked  with  inflammation,  it  gives  the  most  intense  pain. 
Its  nerves  and  vessels  come  from  the  ciliary  branches. 

Choroid  coat,  (Fig.  98,  B.) — This  membrane  forms  the, sec- 
ond tunic  of  the  eye.  It  is  situated  beneath  the  sclerotic, 
and  connected  to  it  by  cellular  tissue,  vessels  and  nerves. 
It  rests  upon,  but  does  not  adhere  to  the  retina.  It  extends 
from  the  optic  nerve  behind,  to  the  ciliary  ligament  in  front, 
which  latter  corresponds  to  the  place  of  junction  between 
the  sclerotic  and  cornea.  In  a  word,  it  lines  and  is  coex- 
tensive with  the  inner  surface  of  the  sclerotic. 

Its  posterior  surface  is  pierced  by  the  optic  nerve.  Its 
anterior  portion  presents  a  large  opening  for  the  reception 
of  the  iris.  Its  color  is  of  a  dark  brown  on  the  external 
surface,  while  its  inner  surface  is  of  a  deep-black.  Its  struc- 
ture is  soft  and  extremely  vascular.  It  has  been  divided 
into  three  layers,  an  external  or  venous,  a  middle  or  arte- 
rial, and  an  internal  or  pigmentary.  Such  a  division  is 
very  justly  regarded  as  of  little  utility,  since  it  is  purely 
artificial.  This  coat  is,  in  fact,  but  one  membrane  highly 
organized  and  vascular.  It  is  believed  to  equal  in  vascu- 
larity  any  of  the  mucous  membranes,  and  has  upon  its 
outer  surface  a  number  of  large  veins,  which  from  their 
peculiar  arrangement  are  called  vasa  vorticosa,  and  con- 
stitute what  is  called  the  first  layer ;  beneath  this  is  seen  a 
beautiful  net-work  of  arterial  capillaries,  called  after  Kuysch, 
the  tunica  Euyschiana.  It  is  composed  of  the  ciliary  arte- 
ries and  nerves,  which  penetrate  the  choroid  from  behind 
in  great  numbers,  round  the  optic  nerve  and  supply  this 
tissue.  The  longer  ciliary  arteries,  with  the  nerves,  pass 
on  to  the  ciliary  ligament,  and  through  it  to  the  iris,  to 
which  organ  the  nerves  seem  chiefly  destined.  Beneath 
this  arterial  layer,  the  microscope  reveals  a  delicate  mem- 
brane, forming  the  internal  lamina  of  the  choroid,  composed 
of  nucleated  hexagonal  cells,  disposed  in  several  lamina, 
and  containing  the  black  pigment.  This  is  the  pigment- 
ary membrane. 


THE  EYE. 


335 


This  pigment  pervades  the  whole  of  the  choroid,  but  is 
found  to  be  more  abundant  on  its  internal,  than  on  its  ex- 
ternal surface ;  and  more  abundant  and  of  a  deeper  color, 
posteriorly  and  anteriorly,  than  laterally.  The  sclerotic  is 
stained  by  the  pigment.  It  is  of  deeper  color  in  the  child, 
and  paler  and  less  in  quantity  in  the  old.  It  is  entirely 
wanting  in  Albinos,  and  vision  is  in  consequence  defective. 
This  pigment  is  wanting  in  the  bottom  of  the  eye  of 
many  of  the  inferior  animals,  as  the  sheep,  ox,  &c.,  and  in 
place  of  it  there  is  seen  a  beautiful,  shining,  metallic  sur- 
face called  tapetum.  The  use  of  the  pigment  is  to  darken 
the  interior  of  the  eye,  to  absorb  the  superfluous  rays  of 
light,  and  prevent  their  being  reflected  back  upon  the  ret- 
ina. For  the  same  reason  the  interior  of  the  telescope  is 
blackened. 

There  are  other  parts  however,  besides  the  choroid,  which 
have  this  black  pigment,  and  which  being  also  in  close  con- 
nection with  it,  will  now  be  noticed.  These  are  the  ciliary 
processes  and  iris,  (Fig.  99.) 

FlG-  "•  There  is  a  circular  band  about 

a  line  and  a  half  broad,  called 
the  ciliary  ligament,  (Fig.  98,  B,) 
which  serves  to  connect  togeth- 
er the  sclerotica,  cornea,  cho- 
roid, and  iris.  It  is  of  a  fibro- 
cellular  structure,  soft,  of  a 
grayish  white  color,  and  not 
blackened  by  the  pigment. 
The  ciliary  arteries  and  nerves 
enter  this  ligament,  and  are 
traced  through  it  to  the  iris.  From  the  nerves  which  Soem- 
mering  saw  it  contain,  he  considered  it  a  nervous  ganglion. 
It  has  also  been  considered  a  muscular,  tendinous,  and 
glandular  structure.  A  small  canal  is  seen  within  this  lig- 
ament, called  after  its  discoverer,  the  canal  of  Fontana. 

FIG.  99  represents  a  transverse  section  of  the  globe  of  the  Eye  seen  from 
within,  o  Cut  edge  of  the  three  tunics  of  the  eye.  6  Pupil,  c  Iris,  d  Ciliary 
processes,  e  Front  border  of  the  retina.  , 


336  THE  EYE. 

The  function  of  this  ligament  appears  to  be  purely  me- 
chanical. 

Ciliary  processes,  (Fig.  99.) — Dissection. — Continue  the 
circular  incision  made  in  the  sclerotic,  through  the  choroid, 
and  on  looking  into  the  anterior  half  of  the  divided  eye 
from  behind,  there  is  seen  a  radiated  disc  of  perfectly  regu- 
lar form.,  surrounding  the  crystalline  lens,  which  from  its 
resemblance  to  a  radiated  flower,  is  called  the  corona  ciliaris. 
The  several  rays  of  this  crown  constitute  the  ciliar}r  pro- 
cesses. 

These  processes  are  delicate  folds  of  the  choroid  mem- 
brane, extending  from  the  ciliary  ligament  to  the  posterior 
surface  of  the  iris,  and  forming  a  ruffle  on  the  forepart  of 
the  vitreous  humor,  around  the  circumference  of  the  crys- 
talline lens.  They  are  small,  triangular  in  shape,  about 
sixty  or  seventy  in  number,  according  to  Zinn,  and  from  a 
line  to  two  lines  in  length.  Between  each  pair  of  these 
processes,  a  corresponding  one  from  the  hyaloid  membrane, 
extends  into  and  fills  up  the  spaces;  thus  forming  a  kind 
of  dove-tailing  union,  which  completes  the  posterior  wall  of 
the  aqueous  chamber,  and  prevents  the  fluid  from,  flowing 
back  in  that  direction. 

The  ciliary  processes  are  covered  with  the  pigment.  If 
this  be  washed  off,  they  are  seen  to  be  very  vascular,  of  a 
grayish  color,  and  continuous  with  the  choroid. 

Function. — Various  opinions  are  entertained  as  to  the 
use  of  these  processes.  Some  believe  them  to  be  muscular, 
and  to  have  the  power  of  regulating  the  focal  distance  of 
the  eye.  Others  suppose  that  they  consist  of  a  venous 
erectile  structure,  and  are  connected  with  the  motions  of  the 
iris.  Others,  again,  say  that  they  secrete  the  aqueous  hu- 
mor— while  others  think,  with  more  plausibility,  that  they 
secrete  or  furnish  the  black  pigment  with  which  they  are 
covered,  to  arrest  any  superfluous  rays  which  may  enter 
the  eye. 

Iris,  (Fig.  99.) — This  organ,  so  called  from  the  variety 
of  its  color,  is  situated  behind  the  cornea  and  in  front  of 
the  lens,  and  is  seen  suspended  as  a  perpendicular  curtain, 


IRIS — STRUCTURE.  337 

dividing  the  front  of  the  eye  into  two  chambers,  the  ante- 
rior and  posterior.  These  chambers  contain  the  aqueous 
humor,  in  which  the  iris  moves  freely.  The  anterior 
chamber  extends  from  the  cornea  to  the  iris ;  the  posterior 
from  the  iris  to  the  lens.  The  iris  is  circular  in  its  form 
in  the  human  eye,  and  oblong,  either  transversely  or 
vertically,  in  many  of  the  inferior  animals,  li  has  in  its 
centre  an  opening  called  the  pupil.  The  size  of  the  pupil 
varies  according  to  the  intensity  of  the  light,  the  sen- 
sibility of  the  retina,  and  the  distance  of  the  object.  When 
the  light  is  strong,  the  object  near,  and  the  retina  sensi- 
ble, the  pupil  contracts,  while  in  the  opposite  condition  of 
things  it  dilates. 

The  external  circumference  of  the  iris  is  attached  to  the 
ciliary  ligament.  Its  internal  circumference  forms  the 
margin  of  the  pupil.  Its  anterior  surface  is  flat,  and  pre- 
sents the  variety  of  color  from  which  it  has  been  called  iris 
or  rainbow.  There  is  stated  to  be  a  resemblance  between 
the  color  of  the  iris  and  the  hair.  In  most  fish  it  is  found 
to  present  a  metallic  lustre.  The  posterior  surface  of  the 
iris  is  covered  with  a  thick  layer  of  dark  pigment,  and  from 
its  resemblance  to  the  ripe  purple  grape,  is  called  uvea. 

Structure. — The  structure  of  the  iris  is  regarded  as  essen- 
tially muscular,  and  has  been  compared  to  the  columnse 
carneas  and  chordae  tendineaa  of  the  heart. 

On  the  anterior  surface  of  the  iris  are  seen  projecting 
lines  and  intervening  depressions.  Some  of  these  lines  sur- 
round the  pupil  after  the  manner  of  a  sphincter ;  others 
radiate  from  the  pupil  towards  the  circumference  of  the 
iris,  while  others  are  described  as  interlacing  and  bifur- 
cating, and  ending  in  small  projections.  The  radiated 
fibres  mingle  with  the  circular  somewhat  after  the  manner 
of  the  muscles  of  the  mouth,  with  the  orbicularis  oris. 
This  arrangement  of  the  muscular  fibres  satisfactorily  ex- 
plains the  functions  of  the  iris.  When  it  is  required  that 
the  pupil  shall  contract,  the  sphincter  or  circular  fibres 
afford  the  means  of  doing  it,  and  shutting  out  the  light ; 
when  it  is  necessary  to  open  the  pupil,  the  dilatation  is 
22 


338  IMS — STRUCTME. 

effected  by  the  radiating  fibres,  drawing  it  apart,  wliile  at 
the  same  time  the  circular  ones  are  relaxed. 

The  posterior  surface  is  deeply  stained,  as  stated,  with 
the  black  pigment,  which  is  said  to  be  protected  by  the 
very  delicate  membrane  of  the  aqueous  humor. 

The  iris  is  abundantly  supplied  with  blood  vessels  and 
nerves.  The  arteries  come  from  the  long  ciliary,  which, 
after  entering  the  sclerotic  behind,  pass  forward  between 
this  coat  and  the  choroid,  one  on  either  side  of  the  eye, 
parallel  to  the  equator  owdi,  to  the  ciliary  ligament,  here 
each  of  them  divides,  and  after  forming  a  circle  round  the 
circumference  of  the  iris,  sends  off  radiating  branches  which 
converge  towards  the  pupil,  and  there  form  anastomotic 
arches.  Some  muscular  branches  of  the  ophthalmic  also 
supply  the  iris  from  the  front.  The  veins  are  more  numer- 
ous than  the  arteries  and  return  the  blood  either  by  the 
ciliary  veins,  or  into  the  vasa-vorticosa.  The  nerves  of  the 
iris  are  large,  and  are  supplied  by  the  ciliary  nerves,  which 
come  from  the  ophthalmic  ganglion.  This  ganglion  is  con- 
nected with  a  sentient  branch  of  the  ophthalmic,  one  of  the 
divisions  of  the  fifth,  a  motive  nerve,  one  of  the  branches 
of  the  third,  and  with  branches  of  the  sympathetic.  From 
this  source  the  ciliary  nerves,  about  12  or  14  in  number, 
pass  through  the  sclerotic  behind,  and  then  go  forward 
on  the  surface  of  the  choroid  to  the  ciliary  ligament,  which 
they  enter  in  great  numbers,  where  they  are  distributed  to 
the  iris.  From  this  bountiful  supply  of  nerves,  both  of 
sensation  and  motion,  we  can  readily  understand  the  great 
sensibility,  and  the  delicate  and  rapid  movements  of 
the  iris. 

The  iris  is  three  or  four  times  thicker  than  the  choroid, 
and  becomes  thinner  towards  the  pupillary  margin.  The 
pupil  is  closed  the  greater  part  of  uterine  life,  by  a  delicate 
membrane,  called  membrana  pupillaris.  It  is  represented 
as  most  distinct  about  the  fifth  month,  and  as  disappearing 
about  the  seventh.  This  membrane  separates  the  anterior 
and  posterior  chambers  of  the  eye,  and  prevents  any  com- 
munication between  them  till,  as  just  stated,  after  the 


RETINA — STRUCTURE.  339 

seventh  month,  when  it  disappears,  and  the  fibres  of  both 
chambers  mingle  and  pass,  readily,  the  one  into  the  other. 
Cases  are  mentioned,  however,  where  this  membrane  has 
remained  after  birth,  causing  blindness.  This  membrane, 
according  to  M.  Cloquet,  consists  of  two  layers — both  serous 
and  formed — the  one  in  front  of  the  iris,  lining  the  ante- 
rior chamber,  and  constituting  the  anterior  layer,  and  the 
other,  of  the  one  behind  the  iris,  lining  the  posterior  cham- 
ber, and  forming  the  posterior  layer. 

Function. — To  act  as  the  diaphragm  of  the  telescope,  by 
its  black  pigment  intercepting  all  the  rays  of  light  except 
those  passing  through  the  pupil. 

Retina. — The  retina  (Fig.  100)  forms  the  third  or  inner- 
most coat,  constituting  the  membranous  case  of  the  eye.  It 
lines  the  choroid,  and  is  A  FlG  m  B 

in  contact^  with  'the  vit- 
reous humor.  It  is  the 
most  important  of  the 
three  membranes,  as  it 
is  the  seat  of  vision,  and 
is  the  place  where  the 
images  of  objects  are 
painted. 

Dissection. — The  eye  being  kept  under  water,  carefully 
remove  the  choroid,  when  the  retina  is  distinctly  seen. 

Structure. — It  consists  essentially  of  the  expansion  of  the 
optic  nerve,  which  forms  a  middle  layer  of  nervous  coat, 
covered  internally  by  a  vascular  layer,  and  externally  by 
a  serous  one,  discovered  by  Mr.  Jacobs.  The  nervous  coat 
presents  a  bluish  white  appearance,  is  soft,  pulpy,  easily 
torn,  and  extends  forward  to  the  ciliary  processes.  The 
internal  layer,  or  vascular  coat,  is  compared  to  the  pia-ma- 
ter,  and  consists  of  the  minute  branchings  of  the  arteria 

V 

FIG.  100,  A  represents  the  Retina  after  the  removal  of  the  Choroid.  a 
The  Retina.  6  Optic  nerve,  c  Iris,  d  Vitreous  humor,  e  Where  the  ret- 
ina terminates. 

FIG.  100,  B  represents  the  central  artery  of  the  retina,  a  Yellow  spot  of 
Soemerring.  6  Point  of  entrance  of  optic  nerve,  c  Choroid  coat,  s  Sclerotic  coat. 


340  ZONULA  CILIABIS — CORNEA. 

centralis,  the  central  artery  of  the  retina,,  which  pierces  the 
optic  nerve,  and  then,  by  its  expansion,  forms  the  principal 
support  for  the  nervous  layer.  The  nervous  layer  is  de- 
scribed by  Treviranus,  as  consisting  of  cylindrical  tubes,  or 
fibres  extending,  in  every  direction,  from  the  optic  nerve, 
and  terminating  in  papilla?  which  are  in  contact  with  the 
hyaloid  membrane. 

The  external  or  serous  layer  separates  the  retina  from 
the  pigmentary  coat  of  the  choroid,  and  when  suspended 
in  water,  is  seen  as  an  extremely  delicate  membrane,  which 
under  the  microscope  presents  granules  having  a  tesselated 
arrangement.  On  the  inner  surface  of  the  retina,  at  the 
bottom  of  the  eye,  where  the  optic  nerve  enters,  a  dark 
point  is  seen,  called  the  porus  options  ;  through  this  the 
arteria  centralis  passes,  and  then  divides. 

From  this  point,  about  a  line  and  a  half  to  Jhe  outside, 
is  seen  a  small,  circular  spot,,  having  a  yellowish  border, 
called  the  foramen  of  Soemerring,  or  punctum  aureum.  This 
spot  corresponds  to  the  axis  of  the  eyes,  and  is  said  not  to 
exist  in  the  foetus.  It  is  found  in  man  and  the  quadru- 
mana — that  is,  in  all  animals  the  axes  of  whose  eyes  are 
parallel.  It  is  not  seen  in  the  horse,  the  ox,  nor  other 
mammalia,  in  birds  nor  in  fish.  This  spot  is  not  a  fora- 
men, as  supposed  by  Soemerring,  but  is  found  to  be  covered 
both  by  the  vascular  layer,  and  the  serous  layer  of  Jacobs, 
there  being  a  depression,  and  an  apparent  deficiency  of  the 
nervous  substance  at  this  point. 

Zonula  Ciliaris. — This  is  a  term  applied  to  the  thin  vas- 
cular structure  connecting  the  anterior  surface  of  the  lens, 
with  the  anterior  margin  of  the  retina.  It  is  found  to 
present  folds,  corresponding  with,  and  received  between 
the  ciliary  processes,  arranged  in  a  radiated  form,  and 
stained  with  the  pigment  around  the  lens.  The  membra- 
nous case  of  the  ball  of  the  eye  thus  formed  of  its  three 
coats,  the  sclerotic,  choroid,  and  retina,  contains  four 
refractive  bodies,  or  media  of  light:  the  cornea,  aqueous 
humor,  crystalline  lens,  and  vitreous  humor. 

Corneaj  (corneus,  horny,)  Fig.  98. — This  structure  occu- 


CORNEA — STRUCTURE.  341 

pies  the  anterior  fifth  of  the  globe  of  the  eye,  and  is  con- 
nected with  the  sclerotica  at  the  ciliary  ligament,  by  a 
very  firm  union.  The  cornea  stands  out  prominent  from 
the  sclerotic,  somewhat  after  the  manner  of  the  crystal  of  a 
watch.  It  is  a  perfectly  transparent  body,  highly  polished, 
convex  on  its  anterior  surface,  and  concave  on  its  posterior; 
thus  presenting  a  lens  of  the  concavo-convex  form.  Its  shape 
is  spherical,  and  represents  the  segment  of  a  smaller  sphere 
placed  on  that  of  a  larger.  Its  transverse  diameter  ex- 
ceeds the  vertical  by  about  one  line,  which  is  found  to  be 
owing  to  the  overlapping  of  the  sclerotic  upon  its  superior 
and  inferior  border.  Its  density  is  slightly  greater  in  the 
centre  than  at  the  circumference.  Its  structure  is  complex 
and  consists  of  a  variety  of  different  tissues,  as  the  tunica 
conjunctiva,  the  cornea  proper,  cornea  elastica,  and  the  lining 
membrane  of  the  anterior  chamber. 

The  tunica  conjunctiva  is  a  fine  layer,  so  closely  adhering 
to  the  cornea  as  to  have  its  existence  denied  by  some  anat- 
omists, though  prolonged  maceration  has  satisfactorily 
proven  its  presence,  and  its  continuity  with  that  covering 
the  sclerotic.  It  is  found  to  be  very  sensitive,  and  to  con- 
sist of  cells,  of  which  the  superficial  are  flat,  while  the 
deeper  are  round,  and  contain  a  transparent  fluid  which, 
soon  after  death,  becomes  opaque  and  white,  forming  that 
peculiar  film  seen  then  upon  the  eye. 

The  cornea  proper  is  composed  of  transparent  lamina, 
which  may  be  few  or  many,  according  to  the  pleasure  of 
the  dissector,  and  which  are  connected  together  by  the  most 
delicate  cellular  tissue  containing,  it  is  said,  a  small  quan- 
tity of  fluid  by  which  these  lamina  are  kept  in  their  proper 
relations  with  each  other. 

These  lamina  can,  by  a  slight  rubbing  between  the  fin- 
gers, be  made  readily  to  glide  the  one  upon  the  other. 
Their  transparency  is  destroyed  by  boiling,  and  they  be- 
come permanently  opaque;  deposition  of  lymph  among  the 
layers,  from  inflammation,  produces  the  same  result,  causing 
what  is  called,  opacity  of  the  eye.  The  several  layers  of 
the  cornea  proper,  though  somewhat  resembling  cartilage, 


342  AQUEOUS  HUMOR. 

are  supposed  to  be  a  peculiar  modification  of  fibro-cellular 
tissue. 

The  cornea  elastica  is  posterior  to  the  cornea  proper,  and 
is  characterized  by  the  very  singular  fact  that  its  trans- 
parency is  not  in  the  least  effected  by  any  of  the  agencies 
which  destroy  that  of  the  true  cornea.  It^is  a  strong, 
though  thin,  elastic  cartilaginous  layer,  in  close  connec- 
tion with  the  cornea.  Its  function  is  to  support  and  pre- 
serve the  proper  curvature  of  the  cornea. 

The  lining  membrane  of  the  anterior  aqueous  chamber 
forms  the  fourth  and  last  layer  of  the  cornea.  It  is  of  such 
extreme  delicacy,  that  its  existence  is  rather  inferred  than 
proved  by  dissection. 

The  cornea,  in  its  healthy  state,  has  no  red  vessels, 
though  when  inflamed,  is  highly  vascular,  and  though  no 
nerves  have  been  satisfactorily  traced  into  it,  its  surface  is 
quite  sensible.  Thus  constituted,  the  cornea  presents  the 
most  perfectly  transparent  lens,  and  is  the  first  of  the 
media  through  which  the  light  has  to  pass  before  reaching 
the  retina.  From  its  great  convexity  and  density,  it  pow- 
erfully refracts  and  converges  the  light  in  its  passage 
through  it. 

Aqueous  humor. — This  forms  the  second  refracting  me- 
dium in  order,  and  is  immediately  behind  the  cornea,  oc- 
cupying the  cavity  between  this  latter  and  the  crystalline 
lens.  It  consists  of  a  perfectly  transparent  and  colorless 
fluid,  secreted  by  the  lining  membrane  of  this  cavity.  It  is 
called  aqueous  from  its  resemblance  to  water,  its  specific 
gravity  differing  very  little  from  that  liquid.  Analysis 
makes  it  to  consist,  in  100  parts,  of  water  98,  and  the  re- 
maining two  parts,  of  chloride  of  sodium  and  albumen. 

The  aqueous  humor  fills  both  the  anterior  and  posterior 
chambers  of  the  eye,  having  free  and  easy  communication 
through  the  pupil. 

This  humor  being  fluid,  and  consequently  less  dense 
than  the  cornea,  will  not,  according  to  the  laws  of  the  re- 
fraction of  light,  so  strongly  converge  the  rays  in  their  pas- 
sage through  itj  but  on  the  contrary,  cause  them  rather  to 


CRYSTALLINE  LENS.  343 

diverge  from  the  axis  of  vision.  The  light  on  leaving  this 
fluid  falls  on  the  next  medium,  L  e.  the  crystalline  lens, 
(Fig.  98.) 

The  lens  is  a  beautiful  double  convex  body,  situated  in 
a  depression  in  front  of  the  vitreous  humor,  and  behind 
the  pupil.  It  is  more  convex  posteriorly  than  in  front,  and 
has  its  axis  on  a  line  with  that  of  the  pupil. 

Its  form  varies:  in  the  foetus  it  is  more  spherical;  in  the 
adult  the  anterior  and  posterior  convexities  are  greater, 
while  in  old  age  these  again  diminish.  This  variation  of 
form  is  also  seen  in  different  individuals  of  the  same  age, 
accounting  for  the  different  powers  of  vision  in  each.  For 
example,  when  the  convexity  of  the  lens  is  excessive,  the 
rays  of  light  will  be  refracted  too  powerfully,  and  be 
brought  to  a  focus  too  soon,  and  in  front  of  the  retina,  pro- 
ducing that  kind  of  defect  of  vision  called  myopia,  or  short 
sightedness.  The  reverse  of  this  occurs  in  old  people,  when 
the  lens  is  too  flat,  giving  rise  to  that  defect  of  sight  called 
presbyopia  or  far-sightedness.  In  this  case  the  focus  is 
thrown  behind  the  retina.  The  color  of  the  lens  varies  as 
much  as  its  form.  It  has  rather  a  pinkish  tint  in  the 
foetus,  is  perfectly  clear  in  the  adult,  and  of  an  amber  color 
in  the  old.  Its  density  also  varies,  being  much  greater  in 
the  centre  than  on  the  surface.  The  centre  is  firm  and  has 
been  compared  to  gum-arabic,  and  called  the  nucleus. 
From  this  point  to  the  surface,  it  becomes  less  and  less 
dense,  so  that  the  surface  is  semi-fluid,  though  every  part 
of  the  lens  has  greater  density  than  either  of  the  other  hu- 
mors. Berzelius  gives  the  following  analysis :  water  58, 
peculiar  matter*  35.9,  hydro-chlorates,  lactates,  and  animal 

*The  peculiar  matter  alluded  to  in  Berzelius's  analysis  has  since  been  shown 
to  be  globulin,  a  substance  which  is  also  found  in  conjunction  with  faemoftn,  for 
the  blood  corpuscles.  It  is  probably  secreted  by  the  lens  from  the  blood  fur- 
nished it  by  the  capsular  artery,  but  how  this  substance  is  so  perfectly  separated 
from  the  haematin,  which  every  where  else  accompanies  it,  remains  a  pro- 
found mystery. 

It  exists  not  in  the  tissue  of  the  lens,  but  is  contained  in  the  form  of  a  very 
concentrated  solution  in  the  cells  of  that  organ.  The  object  of  it  is,  of  course, 
still  further  to  correct  chromatic  aberration,  by  adding  another  highly  refractive 


344  CRYSTALLINE  LENS. 

matter  soluble  in  water  1.3,  insoluble  membranous  matter 
2.4.  The  lens  is  stated  to  contain  both  gelatine  and  albu- 
men, but  no  traces  of  fibrin  have  been  detected.  By  burn- 
ing it  to  ashes,  traces  of  iron  are  found. 

The  structure  of  the  lens  is  not  satisfactorily  settled.  All 
are  agreed  that  it  consists  of  concentric  layers,  which  are 
easily  demonstrated  and  rendered  very  distinct  by  boiling 
or  immersion  in  a  dilute  acid.  In  this  manner  the  layers 
are  seen  to  be  placed  one  above  the  other,  like  the  sev- 
eral strata  of  an  onion,  and  increasing  in  density  as  they 
approach  the  centre.  These  lamina  seem  to  be  composed 
of  fibres,  extremely  thin,  and  under  the  microscope  present 
a  series  of  fine  teeth  united  together  and  interlocking  with 
each  other.  The  lens  separates  readily  into  three  or  four 
triangular  fragments,  having  their  bases  at  the  circumfer- 
ence, and  their  apices  at  the  centre.  It  is  surrounded  by 
a  membrane  called  the  capsule  of  the  lens.  This  capsule  is 
elastic,  dense,  and  very  transparent,  and  like  the  posterior 
layer  of  the  cornea,  boiling  and  immersion  in  alcohol  do 
not  render  it  opaque  like  the  lens,  and  when  separated, 
after  being  subjected  to  this  operation,  its  transparency  is 
found  to  be  still  preserved. 

The  use  of  this  capsule  seems  evidently  designed  to  pre- 
serve the  form  of  the  lens.  ,  It  is  described  as  containing  a 
small  quantity  of  fluid,  called  the  liquor-morgagni,  which 
by  some  is  thought  to  be  rather  the  result  of  a  cadaveric 
change.  Around  the  circumference  of  the  lens  there  is 
seen  a  triangular  canal  called  the  canal  of  Petit,  which  is 
believed  to  be  formed  by  the  splitting  of  the  lamina  of  the 
hyaloid  membrane  at  the  lens,  one  layer  going  in  front  of 
the  lens,  the  other  behind,  and  leaving  between  the  points 
of  separation  the  above  triangular  canal.  Both  the  lens 

medium  to  the  many  already  described  as  traversed  by  light.  It  is  very  inter- 
esting to  observe,  moreover,  that  nature  has  not  confined  herself  to  an  anatomi- 
cal arrangement  in  order  to  obtain  a  perfect  chromatic  instrument,  but  has 
also  resorted,  in  this  instance,  to  purely  physical  methods.  She  has  greatly 
increased  the  density  of  this  solution  towards  the  centre  of  the  lens,  and  has 
accomplished  this  by  a  very  gradual  change,  so  that  this  one  fluid  presents  of 
itself  a  variety  of  media  for  the  light  to  traverse. 


VITREOUS  HUMOR.  345 

and  its  capsule  are  frequently  the  seat  of  a  morbid  opacity 
called  cataract.  Hence  we  have  the  lenticular  and  capsular 
cataracts,  which  destroy  the  transparency  of  the  lens  or  of 
its  capsule,  prevent  the  rays  of  light  from  passing  to  the 
retina,  and  consequently  produce  blindness. 

The  vitreous  humor  (Fig.  98)  forms  the  last  of  the  re- 
fracting media.  It  is  also  called  the  hyaloid  ~body,  (voxoj, 
glass,)  from  its  resemblance  to  melted  glass.  It  occupies 
the  posterior  three-fourths  of  the  globe  of  the  eye.  Is  a  per- 
fectly transparent  body,  spheroidal  in  its  shape,  except  in 
its  anterior  portion,  where  there  is  a  depression  for  the  re- 
ception of  the  lens,  and  lies  in  contact  with  the  whole  inner 
surface  of  the  retina,  which  is  expanded  over  it. 

This  humor  is  of  a  gelatinous  or  semi-fluid  consistence, 
holding  a  medium  refractive  power  between  the  lens  and 
aqueous  humor.  It  consists  of  a  very  delicate,  transparent 
membrane,  called  the  hyaloid  membrane,  and  a  fluid  sub- 
stance not  unlike  water. 

This  membrane,  besides  enclosing  the  vitreous  humor, 
sends  into  its  interior  numerous  processes,  which,  inter- 
lacing and  uniting,  form  a  very  fine  cellular  tissue,  con- 
taining the  humor  in  its  various  cells — thus  differing  from 
the  aqueous  which  is  received  in  a  single  capsule.  It  has 
sufficient  strength  to  support  the  humor  when  suspended, 
and  on  being  punctured,  the  fluid  is  seen  to  escape  drop  by 
drop,  till  the  whole  is  discharged.  If  inflated  and  dried, 
or  immersed  in  alcohol,  the  interior  septa  and  cellular  ar- 
rangement will  become  still  more  evident. 

The  vitreous  fluid,  chemically,  is  found  to  diifer  very  little 
from  the  aqueous,  being  formed  principally  of  water,  and 
about  two  per  cent,  of  animal  and  saline  matter.  The 
vitreous  humor  is  supplied  with  blood  by  a  small  artery 
from  the  arteria  centralis,  which  is  seen  to  take  a  "tortu- 
ous" course  from  behind,  and  lose  itself  on  the  capsule  of 
the  lens.  This  vessel,  it  is  supposed,  also  supplies  the 
hyaloid  membrane.  The  vascular  layer  of  the  retina  like- 
wise sends  vessels  into  the  vitreous  humor  as  well  as  the 
ciliary  processes  in  front. 


346  NERVES  OF  THE  EYE-BALL. 


SUMMARY  OF  BLOOD  VESSELS  AND  NERVES  OF  THE  BALL  OF  THE  EYE. 

The  ophthalmic  artery  sends  off  the  ciliary  branches  which 
are  divided  into  the  short  and  long.  The  short  are  from  10 
to  20  in  number,  they  surround  the  optic  nerve,  penetrate  the 
sclerotic  coat  behind,  and  are  distributed  upon  the  choroid, 
some  of  the  branches  going  as  far  forward  as  the  iris  and 
ciliary  processes.  The  long  ciliary  are  two  in  number,  one 
on  either  side  of  the  eye,  which  pass  to  the  ciliary  ligament 
and  iris,  while  the  arteria  centralis,  penetrating  the  optic 
nerve  and  passing  through  its  centre,  supplies  the  retina, 
vitreous  humor,  and  crystalline  lens. 

FIG.  101. 


The  nerves  of  the  eye-lall  (Fig.  101)  come  from  the  oph- 
thalmic ganglion.  This  ganglion,  called  also  lenticular  and 
ciliary,  is  situated  in  the  posterior  part  of  the  orbit,  between 
the  rectus  externus  muscle,  and  optic  nerve.  It  is  imbed- 
ded in  adipose  structure,  and  presents  a  reddish  aspect.  It 
is  described  as  having  four  angles,  the  posterior  superior 

FIG.  101  represents  the  Nerves  of  the  Eye-ball,  a  Optic  nerve,  b  Trunk 
of  the  motor  oculi.  c  Inferior  branch  of  this  latter  nerve,  d  Ganglion  of 
Gasser.  e  Ophthalmic  or  first  branch  of  the  fifth.  /  Nasal  branch  of  the 
ophthalmic,  g  Superior  maxillary  or  second  division  of  the  fifth,  h  Inferior 
maxillary  or  third  division  of  the  fifth,  i  Posterior  coat  of  the  sclerotica, 
where  the  ciliary  nerves  enter,  j  Choroid  coat,  k  Front  portion  of  the 
sclerotica.  I  Lower  segment  of  the  cornea,  m  Ciliary  ligament,  n  Iris,  o 
Pupil,  p  Sensitive  root  of  the  ophthalmic  ganglion,  q  Corresponding  motor 
branch  of  this  sensitive  root,  r  Sympathetic  filament,  s  Ophthalmic  ganglion. 
t  Long  ciliary  nerves.  M  Anastomosis  between  the  short  ciliary  nerve  and 
nasal  branch,  v  Ciliary  nerves  from  ophthalmic  ganglion,  w  Ciliary  nerves 
anastomosing  with  each  other,  x  Motor  branches  of  the  same  nerves  y  Ciliary 
nerves  that  penetrate  the  sclerotica,  and  supply  the  conjunctiva. 


NERVES  OP  THE  EYE-BALL.  347 

receiving  a  filament  from  tlie  nasal  branch,  of  the  ophthal- 
mic, and  the  posterior  inferior  a  motor  branch  from  the 
third  pair;  while  from  the  anterior  angles  proceed  the 
ciliary  nerves.  These  are  from  ten  to  twenty  in  number, 
accompany  the  ciliary  arteries  through  the  sclerotic  coat, 
surround  the  optic  nerve  and  proceed  forward  to  the  ciliary 
ligament  between  the  sclerotic  and  choroid,  and  terminat- 
ing, as  before  described,  upon  the  iris.  Filaments  of  the 
sympathetic  also  go  to  this  ganglion.  The  ophthalmic  gang- 
lion is  thus  seen  to  embody  nerves  both  of  motion  and  sen- 
sation, the  former  coming  from  the  third,  the  latter  from 
the  fifth,  besides  having  sympathetic  branches. 

The  eye  proper,  or  the  ball,  is  thus  seen  to  be  a  very 
complex  organ — consisting  of  a  great  variety  of  parts,  at 
once  most  delicate  and  beautiful  in  their  structure,  as  well 
as  most  surprising  and  admirable  in  their  nice  adaptations 
to  each  other  and  to  light. 

It  may  now  be  proper  to  make  a  remark  or  two  on  the 
whole  collectively,  in  their  conjoint  action,  and  harmonious 
co-operation  in  enabling  us  to  see. 

Light,  in  coming  from  any  object,  falls  first  upon  the 
cornea,  which  being  a  convex  lens  on  its  anterior  surface, 
and  more  dense  than  the  air,  refracts  the  light  and  causes 
it  to  converge  towards  a  focus  ;  after  leaving  the  cornea  it 
passes  through  the  aqueous  humor,  a  medium  less  dense, 
consequently  having  less  refraction,  and  producing  rather 
a  divergence  or  bending  of  the  rays  from  the  perpendicular; 
on  leaving  the  aqueous  fluid  the  rays  pass  next  in  order 
through  the  crystalline  lens,  and  here,  from  the  double  con- 
vexity and  density  of  this  body,  they  undergo  a  powerful 
convergence  or  bending  to  a  focus — to  obviate  which,  before 
reaching  the  retina  they  are  made  to  pass  through  another 
medium,  the  vitreous  humor,  which  is  neither  so  convex 
nor  so  dense,  and  are  thus  brought  to  the  proper  focal  dis- 
tance by  the  time  they  reach  the  retina  or  seeing  membrane 
of  the  eye. 

The  rays  of  light  in  passing  through  the  lenses  of  the 
telescope  would  be  liable  to  confusion,  and  the  production 


348  ABERRATIONS  OP  LIGHT. 

of  very  indistinct  images,  were  it  not  for  the  diaphragm 
and  the  black  lining  of  this  optical  instrument.  These 
imperfect  images  are  termed  aberrations  of  light,  and  are 
reduced  to  three,  i.  e.,  the  aberration  from  sphericity,  from 
parallax,  and  chromatic  aberration.  Now  nature  has  pro- 
vided in  the  living  eye  contrivances  much  more  perfect,  in 
obviating  these  several  varieties,  than  any  to  be  found  in 
the  workmanship  of  man.  These  consist  of  the  iris,  the 
ciliary  processes,  the  choroid  membrane,  and  the  lenses  of 
different  refracting  power.  The  aberration  of  sphericity  is 
corrected  by  the  iris,  whose  black  pigment  intercepts  all 
the  lateral  rays  which  fall  upon  the  cornea,  and  allows 
only  those  to  enter  which  are  in  the  axis  of  vision.  Were 
it  not  for  this  provision,  all  the  rays  falling  on  any  por- 
tion of  the  cornea,  not  in  a  line  with  the  pupil,  would 
converge  sooner  and  form  different  focal  points,  and  neces- 
sarily produce  indistinct  vision. 

Aberration  from  parallax,  as  it  is  termed,  is  caused  by 
the  rays  of  light  coming  from  distant  objects  in  parallel 
lines,  and  being  consequently  brought  to  a  focus  soon,  and 
near  the  lens,  while  the  rays  from  near  objects  are  diver- 
gent and  do  not  come  to  a  focus  for  a  much  greater  dis- 
tance; for  the  law  is,  the  further  the  object  the  nearer  the 
focus  to  the  lens;  the  focal  distance  behind  the  lens  corre- 
sponds to  the  distance  of  any  object.  The  eye,  it  is  known, 
has  the  power  of  accommodating  itself  to,  and  seeing  at, 
different  distances — but  in  what  this  power  consists  (and 
where  it  resides)  is  not  exactly  agreed.  Some  suppose  the 
lens  to  be  muscular,  and  thereby  capable  of  altering  its 
form,  density  and  distance  from  the  retina,  and  thus  al- 
ways producing  the  proper  focus  at  any  distance  at  all 
within  the  range  of  vision.  By  others  the  muscles,  acting 
upon  and  compressing  the  globe  of  the  eye,  and  thus 
changing  its  form,  are  supposed  to  furnish  this  power. 
Others  again  assign  the  cause  to  a  change  in  the  con- 
vexity of  the  cornea. 

Chromatic  aberration,  or  the  confusion  in  sight  arising 
from  the  decomposition  of  the  light  in  its  passing  through 


APPENDAGES  OF  THE  EYE.  349 

the  lenses,  and  producing  a  variety  of  colors,  as  seen  in 
the  solar  spectrum,  is  corrected  in  the  living  eye  by  the 
presence  of  different  media,  each  having  different  density 
and  different  refracting  power,  thus  balancing  each  other, 
and  thereby  preventing  any  confusion  arising  from  color. 

APPENDAGES  OF  THE  EYE. 

The  Appendages  of  the  Eye  (tutamina  oculi)  consist  of  the 
Muscles,  Eyebrows j  Eyelids,  and  Lachrymal  Apparatus. 

The  Muscles  Flo  102t 

belong  to  the 
globe  of  the 
eye,  the  upper 
eyelids  and  the 
tar  sal  cartil- 
ages. To  the 
globe  belong 
six  muscles, 
four  straight 
and  two  ob- 
lique. The  straight,  called  recti,  consist  of  the  superior, 
inferior ,  external  and  internal  recti. 

Dissection. — The  rectus  superior,  or  levator  oculi,  situ- 
ated beneath  the  upper  eyelid  and  the  levator  palpebrarum 
muscle,  is  exposed  by  removing  the  roof  of  the  orbit,  which 
is  done  by  sawing  the  frontal  bone  at  the  outer  and  inner 
extremities  of  its  orbitar  edge,  when  with  a  few  blows  by 
the  hammer  upon  the  superciliary  portion,  it  can  be  re- 
moved. The  brain  is  supposed  to  have  been  first  taken 
away. 

This  muscle  arises  from  the  superior  margin  of  the  optic 
foramen  small  and  tendinous,  also  from  the  fibrous  sheath 
of  the  optic  nerve.  It  passes  forward  over  this  nerve  and 
the  superior  portion  of  the  ball,  and  is  inserted  into  the 
sclerotic  by  small  tendinous  fibres  near  the  cornea. 

Fia.  102  represents  the  Muscles  of  the  Eye-ball,  o  Optic  nerve.  6  Trige- 
minus  or  fifth  pair  of  nerves,  c  Ganglion  of  the  fifth  pair  or  of  Gasser.  d 
Superior  oblique  muscle,  e  Rectus  superior.  /  Rectus  externus.  g  Rectus 
inferior,  h  Obliquus  Inferior,  i  Ball  of  eye.  j  Levator  palpebrarum. 


350  APPENDAGES  OP  THE  EYE. 

Function. — To  raise  the  eye.  It  covers  the  third,  nasal, 
and  optic  nerves,  with  the  ophthalmic  artery. 

Eectus  inferior  (or  depressor  oculi,)  situated  on  the  infe- 
rior margin  of  the  optic  foramen  by  a  ligament  common  to 
this  muscle,  and  the  external  and  internal  rectus,  called 
the  ligament  of  Zinn,  and  from  the  fibrous  sheath  of  the 
optic  nerve,  passes  forward  beneath  the  optic  nerve,  and 
upon  the  floor  of  the  orbit,  separated  from  it  by  the  in- 
ferior oblique  muscle  and  some  adipose  matter,  and  ter- 
minates in  a  tendon  which  is  inserted  into  the  under  sur- 
face of  the  sclerotica,  near  the  cornea. 

Function. — To  depress  the  eye. 

The  Eectus  externus,  (or  abductor  oculi^)  situated  on  the 
outer  portion  of  the  orbit,  is  the  longest  of  the  recti  mus- 
cles. It  arises  by  two  heads,  one  from  the  external  margin 
of  the  optic  foramen  and  optic  sheath,  the  other  from  the 
ligament  of  Zinn.  The  muscle  passes  forward,  ends  in  a 
tendon  which  is  inserted  into  the  outer  surface  of  the  scle- 
rotica near  the  cornea;  between  the  two  heads  of  this  mus- 
cle, the  third,  nasal,  and  sixth  nerves  pass,  the  latter  nerve 
being  wholly  spent  upon  this  muscle.  It  is  separated  from 
the  optic  nerve  and  the  ball  of  the  eye,  by  the  lenticular 
ganglion,  ciliary  vessels,  nerves,  and  fascia. 

Function. — To  abduct  or  roll  the  eye  outward. 

The  Eectus  internus,  (or  adductor  ocutt,)  situated  upon  the 
inner  portion  of  the  orbit,  arises  from  the  inner  margin  of 
the  optic  foramen  by  the  ligament  of  Zinn,  and  from  the 
optic  sheath — it  passes  forward,  becomes  tendinous,  and  is 
inserted  into  the  inner  surface  of  the  sclerotica  near  the 
cornea. 

Function. — To  roll  the  eye  inward. 

The  dbliquus  superior,  (or  troclileator^)  situated  at  the 
upper  and  inner  part  of  -  the  orbit,  is  a  long  and  slender 
muscle,  arising  by  a  small  tendon  from  the  inner  margin  of 
the  optic  foramen,  and  from  the  sheath  of  the  optic  nerve; 
it  proceeds  forward  and  upward,  along  the  os-planum  to  the 
internal  angular  process  of  the  frontal  bone,  beneath  and 
rather  behind*  which,  this  muscle  forms  a  round  tendon 


APPEXDAGES  OP  THE  EYE.  351 

which  passes  through  a  cartilaginous  pully  at  this  place, 
and  is  then  reflected  backward  beneath  the  superior  rec- 
tus,  to  be  inserted  into  the  outer  part  of  the  sclerotica,  about 
half  way  between  the  cornea  and  entrance  of  the  optic 
nerve.  The  fourth  nerve  occupies  its  upper  surface,  the 
nasal  nerve  and  ophthalmic  artery  are  on  its  lower  sur- 
face. 

The  pully  of  this  muscle  is  attached  by  a  movable  liga- 
ment to  the  bone,  and  is  lined  by  synovial  membrane, 
which  admits  of  free  play. 

Function. — To  roll  the  eye  obliquely  downward  and 
outward. 

Obliquus  inferior,  situated  at  the  anterior  and  inferior  part 
of  the  orbit,  is  a  thin  and  flat  muscle,  and  arises  from  the 
orbital  plate  of  the  superior  maxillary  bone,  above  the 
infra-orbital  foramen,  and  outside  of  the  lachrymal  groove  : 
it  passes  obliquely  outward  and  backward,  beneath  the 
inferior  rectus,  and  is  inserted  into  the  outer  and  posterior 
part  of  the  sclerotic. 

Function. — To  roll  the  eye  downward  and  inward. 

Levator  palpebrce  superioris,  situated  along  the  roof  of 
the  orbit,  is  a  long,  flat,  and  triangular  muscle,  arising 
from  the  superior  margin  of  the  optic  foramen,  by  tendi- 
nous fibres,  and  passes  foward  to  be  inserted  into  the  upper 
border  of  the  superior  tarsal  cartilage. 

Function. — To  raise  the  upper  eyelid.  The  lower  surface 
of  this  muscle  has  a  branch  of  the  third  nerve  supplying  it ; 
while  the  frontal  branch  of  the  ophthalmic  is  upon  the 
upper  surface 

Teftsor  tarsi,  a  small  muscle  situated  at  the  inner  can- 
thus  of  the  eye,  and  discovered  by  Dr.  Horner.  It  arises 
from  the  "posterior  superior  part  of  the  os-unguis,  and 
advancing  three  lines,  it  bifurcates — one  bifurcation  is  in- 
serted along  the  upper  lachrymal  duct,  and  terminates  at 
its  junction,  or  near  it;"  the  other  has  the  same  insertion 
upon  the  lower  lachrymal  duct.  The  caruncula  lachry- 
malis  is  in  the  angle  of  the  bifurcation.  At  the  inner 
canthus  this  muscle  is  connected  to  the  orbicular  is  pafpe- 


352  THE  NERVES  OF  THE  MUSCLES  OF  THE  EYE. 

brarum,  and  its  nasal  portion  is  described  as  adhering 
closely  to  the  lachrymal  sac. 

Function. — According  to  Homer,  it  dilates  the  lach- 
rymal sac,  thus  producing  a  vacuum  by  which,  through 
atmospheric  pressure,  the  tears  are  constantly  propelled 
into  it.  Another  use  is  also  assigned  it,  i.  e.,  of  keeping 
the  eyelids  in  contact  with  the  ball. 

Fascia  of  Muscles. — The  muscles  of  the  orbit  are  sur- 
rounded by  a  distinct  fascia,  called  the  ocular  fascia,  which 
separates  them  from  the  ball  of  the  eye.  It  is  loose  upon 
the  ball,  and  represented  by  Mr.  Ferrall  as  having  six 
openings  for  the  passage  of  the^  tendons  of  the  several 
muscles,  which  play  through  it  as  so  many  pulleys.  Its 
use  is  supposed  to  be  to  protect  the  ball  of  the  eye  from 
the  action  of  the  muscles,  and  to  connect  and  retain  all 
these  muscles  in  their  proper  relations. 

Combined  action  of  Muscles. — When  the  recti  muscles  act 
in  pairs,  the  eye  is  rolled  in  the  diagonal  of  their  action, 
as  upward  and  inward,  downward  and  inward,  upward 
and  outward,  downward  and  outward.  The  two  oblique, 
acting  conjointly,  draw  the  eye  forward-. 

THE  NERVES  OF  THE  MUSCLES  OF  THE  EYE.    (Fig.  101.) 

These  comprise  the  third,  fourth,  and  sixth,  which  are 
motor  nerves,  with  the  first  or  ophthalmic  division  of  the 
fifth,  which  is  a  nerve  of  sensation. 

These  nerves,  entering  the  orbit  through  the  foramen 
lacerum  superius,  as  described  under  the  head  of  cerebral 
nerves,  are  distributed  as  follows :  The  third  pair,  or  mo- 
tores  oculorum,  divides. into  a  superior  and  inferior  branch. 
The  superior  is  the  smaller  of  the  two,  and,  going  between 
the  two  heads  of  the  rectus  externus  muscle,  over  the  optic 
and  nasal  nerves,  is  distributed  to  the  rectus  superior,  and 
levator  palpebrce  muscle.  The  inferior  or  larger  branch 
passes  to  the  outside  and  below  the  optic  nerve,  then  sep- 
arating into  three  branches,  is  distributed  to  the  inferior 
rectus,  the  rectus  internus,  and  inferior  oblique  muscle. 


THE  NERVES  OF  THE  MUSCLES  OF  THE  EYE.      353 

The  branch  to  this  latter  muscle  sends   a  twig  to  the 
ophthalmic  ganglion. 

The  fourth  pair  (nervi  pathetici  or  trochleares ,  Fig.  16,) 
proceed  above  the  superior  rectus  and  levator  palpebrae, 
obliquely  inward  and  forward,  and  go  to  supply  the  supe- 
rior ojblique  muscle. 

The  sixth  pair,  (motores  externi  or  abducentes,)  after  pass- 
ing between  the  two  heads  of  the  rectus  externus,  proceed 
outward  and  forward,  and  are  distributed  solely  on  the 
ocular  surface  of  this  same  muscle. 

The  fifth  pair,  (nervi  trigemini,)  the  ophthalmic  division^ 
(Fig.  T4,)  is  the  smallest.  It  proceeds  from  the  superior 
angle  of  the  Gasserian  ganglion,  about  an  inch  in  length, 
runs  through  the  cavernous  sinus,  and  here  passes  above 
the  sixth  and  below  the  third  and  fourth  nerves,  receiving 
in  this  sinus  some  filaments  from  the  sympathetic.  It  has 
a  sheath  of  dura-mater,  and  on  reaching  the  orbit  divides 
into  three  branches,  1.  The  lachrymal;  2.  The  frontal;  3. 
The  nasal. 

The  lachrymal  proceeds  outward  and  forward  above  the 
rectus  externus  to  the  lachrymal  gland,  and  is  the  small- 
est of  the  three  branches.  It  accompanies  the  lachrymal 
artery,  and  as  it  approaches  the  gland  it  divides  into  two 
filaments,  one  of  which  passes  through  the  malar  bone  and 
connects  with  the  facial  nerve;  the  other  passes  through 
the  spheno-maxillary  fissure  and  connects  with  the  supe- 
rior maxillary  nerve.  Its  terminating  branches  are  spent 
upon  the  lachrymal  gland,  tunica  conjunctiva  and  upper 
eyelid. 

The  frontal  branch  is  the  largest  of  the  three,  and  pro- 
ceeds forward  above  the  muscles  of  the  orbit,  between  them 
and  the  periosteum,  and  on  approaching  the  superior  orbi- 
tary  margin  divides  into  an  internal  and  external  branch. 
The  internal  or  supra-trochlear  nerve  passes  above  the  troch- 
lea  of  the  superior  oblique  muscle,  connects  with  the  nasal 
nerve,  and  is  distributed,  after  passing  over  the  inner  mar- 
gin of  the  orbit,  to  the  corrugator  supercilii;  occipito-fron- 
talis  and  orbicularis  palpebrarum  muscles. 
23 


354  THE  EYEBROWS. 

The  external  or  proper  frontal  branch,  called  also  supra- 
orbital,  ascends  on  the  forehead  through  the  supra-orbital 
notch  or  foramen,  and  divides  into  numerous  filaments 
supplying  the  muscles  and  scalp  in  this  region,  and  com- 
municating with  its  fellow  of  the  opposite  side  and  with 
the  facial  and  occipital  nerves. 

The  nasal  branch  separates  from  the  ophthalmic  in  the 
cavernous  sinus,  and  entering  the  orbit  between  the  two 
heads  of  the  external  rectus,  proceeds  inward  and  forward 
along  the  inner  surface  of  the  orbit,  below  the  superior 
oblique  muscle,  to  the  anterior  sethmoidal  foramen,  through 
which  it  passes  into  the  cranium  upon  the  cribriform  plate 
of  the  aethmoid  bone,  and  then  descends  through  this  plate 
by  the  side  of  the  crista  galli,  into  the  nose,  where  it  is 
distributed  upon  the  septum  and  posterior  surface  of  the 
nasal  bones,  as  far  as  the  tip  of  the  nose. 

The  nasal  nerve  gives  off,  in  its  course,  a  branch  which 
goes  on  the  outer  side  of  the  optic  nerve,  to  the  ophthalmic 
ganglion ;  also  two  other  branches,  termed  ciliary  nerves, 
which  do  not  connect  with  the  ganglion,  but  go  directly 
into  the  ball  of  the  eye,  through  the  sclerotica,  along  with 
the  rest  of  the  ciliary  nerves.  It  also  sends  off  the  infra 
trochlear  branch,  which  passes  below  the  pulley  of  the 
superior  oblique,  supplying  the  lachrymal  ducts,  sac,  and 
caruncula  lachrymalis — communicates  with  the  superior 
trochlear  nerve,  and  is  finally  distributed  to  the  side  and 
dorsum  of  the  nose. 

The  Function  of  all  these  branches  of  the  ophthalmic,  is 
to  give  common  sensibility,  or  general  feeling  to  all  the 
parts  to  which  they  are  distributed. 

The  superior  and  inferior  maxillary  nerves,  forming  the 
second  and  third  divisions  of  the  fifth,  will  be  found  de- 
scribed under  the  head  of  nerves  of  the  passive  and  active 
organs  of  mastication,  which  see.  The  arteries  supplying 
the  muscles  come  from  the  ophthalmic. 

The  eyebrows  (supercilia)  form  the  upper  boundary  of 
the  orbit,  and  consist  of  a  quantity  of  sub-cutaneous  cellu- 
lar and  adipose  structure,  with  the  corrugatores  supercilii 


THE  EYELIDS.  355 

muscles,  and  muscular  fibres  of  the  occipito-frontales  and 
orbiculares  palpebrarum.  The  hairs  are  arranged  in  two 
rows,  the  superior  inclining  downward  and  outward,  the 
inferior  upward  and  outward.  Both  rows  converge  in  the 
middle,  so  as  to  cause  a  fullness  and  regular  prominence. 

The  function  of  the  eye-brow  is  to  shade  the  eye  from 
too  strong  light,  and  to  shield  it  from  particles  of  dust, 
and  from  the  perspiration. 

The  eyebrow  can  be  elevated  by  the  occipito  frontalis, 
depressed  by  the  orbicularis  palpebrarum,  and  drawn  to- 
wards the  nose  by  the  corrugator  supercilii. 

Blood-vessels  of  the  eyebrows. — The  arteries  come  from 
the  ophthalmic  and  temporal.  The  veins  have  correspond- 
ing names  with  the  arteries  and  discharge  into  the  cavern- 
ous sinus. 

Nerves  of  the  eyebroivs. — These  come  from  the  ophthalmic 
branch  of  the  fifth  pair  and  the  facial. 

The  eyelids  (palpebrce)  form  two  movable  curtains,  sit- 
uated in  front  of  the  eye,  and. adapted  to  protect  this  organ 
from  injury.  The  eyelid  in  man  consists  of  two  por- 
tions, a  superior  and  an  inferior  lid;  while  in  some  animals 
there  is  a  third.  When  the  lids  are  open,  the  points  of 
connection  at  their  inner  and  outer  extremities  are  called 
canthij  angles,  or  commissures. 

The  internal  canthus  presents  a  triangular  space  called 
the  lacus  lachrymalis,  which  encloses  a  little  body,  the 
caruncula  lachrymalis.  On  the  free  margin  of  each  lid,  at 
the  inner  extremity,  and  a  little  to  the  outside  of  the  car- 
uncle, is  seen  an  eminence  called  the  lachrymal  papilla  or 
tubercle.  In  each  of  these  papillae,  at  the  apex,  is  seen  a 
small  opening,  the  punctum  lachrymale,  which  is  the  com- 
mencement of  the  lachrymal  canals,  conducting  the  tears 
to  the  lachrymal  sac. 

The  structure  of  each  eyelid  consists  of  the  integument, 
muscle,  tarsal  cartilage,  tunica  conjunctiva  and  Meiboniian 
glands. 

The  integument  is  thin,  delicate,  loose,  and  remarkable 
for  the  entire  absence  of  fat,  which  would,  in  this  situation, 


356  TARSAL  CARTILAGES — TUNICA  CONJUNCTIVA. 

be  extremely  inconvenient.  The  muscle,  called  orbicularis 
palpebrarum,  has  been  already  described  as  a  broad,  ellip- 
tical sheet  of  pale  semi-circular  fibres,  covering  each  tar- 
sus and  connected  at  each  canthus,  by  whose  action  the 
lids  are  closed. 

The  tarsal  cartilages  are  thin,  elastic  plates  of  fibro  car- 
tilage, which  support  and  preserve  the  form  of  the  eyelids. 
The  one  belonging  to  the  upper  lid  is  semi-lunar,  broad  in 
the  middle  and  tapering  at  either  extremity.  It  lies  be- 
tween the  orbiculari  and  levator  palpebrse  muscles.  Its 
lower  border  or  free  margin  is  thick.  Its  upper  or  orbital 
edge  is  thin,  for  the  attachment  of  the  levator  palpebree 
and  broad  ligament  of  the  tarsus,  which  fixes  the  cartilage 
to  the  base  of  the  orbit.  This  fibrous  ligament  is  continu- 
ous with  the  periosteum  at  the  base  of  the  orbit.  It  is 
thicker  at  the  outer  than  at  the  inner  portion  of  the  lid.  It 
attaches  the  extremity  of  this  lid  to  the  outer  canthus,  and, 
extends  to  the  lower  lid,  which  it  supports  and  connects  in 
a  similar  manner ;  at  the  inner  canthus  the  tendo  oculi 
serves  to  fix  the  tarsi  at  this  point.  The  tarsal  cartilage  of 
the  lower  lid  is  much  narrower  than  that  of  the  superior. 
The  free  margins  of  both  lids  are  furnished  with  strong, 
stiff,  and  curved  hairs,  arranged  in  triple,  sometimes  quad- 
ruple rows,  and  called  cilice.  Those  of  the  upper  lid  are 
longer  and  stronger  than  the  lower,  and  curve  upward. 
Those  in  the  lower  curve  downward,  so  that  when  the  lids 
are  closed,  they  cannot  interfere  with  each  other,  as  they 
only  touch  at  their  convexities.  The  eye-lashes,  thus  ar- 
ranged, serve  to  shade  the  eye  from  the  intensity  of  light, 
and  to  guard  it  from  particles  of  dust  and  foreign  bodies. 

The  tunica  conjunctiva  forms  the  mucous  membrane  of 
the  lids  and  eye.  It  is  situated  on  the  posterior  surface  of 
the  tarsal  cartilages  which  it  lines,  and  is  then  reflected 
upon  the  ball  of  the  eye,  forming  at  the  angle  of  this  re- 
flection in  the  upper  lid,  the  superior,  palpebral  sinus,  and 
in  the  lower  the  inferior  palpebral  sinus.  On  the  eye  it 
covers  about  the  anterior  third,  being  connected  by  cellular 
tissue,  which  is  loose  till  it  reaches  the  cornea.  It  is  traced 


MEIBOMIAN  GLANDS — CARUNCULA  LACHRYMALIS.  35 7 

over  the  cornea  with  difficulty,  so  much  so  that  its  exist- 
ence here  is  deniecf  by  some.  From  the  lids  it  is  continu- 
ous with  the  skin  in  one  direction,  and  in  another  lining 
the  Meibomian  follicles,  excretory  ducts  of  the  lachrymal 
gland,  and  puncta  lachrymalia.  At  the  inner  canthus  of 
the  eye  it  forms  a  semi-lunar  fold,  called  plica  semilunaris, 
which  represents  the  membrana  nictitans  of  quadrupeds, 
or  the  third  eyelid  of  birds.  This  fold  has  a  thin  fibro- 
cartilaginous  plate,  and  is  very  vascular. 

Caruncula  lachry mails. — This  is  a  small  projection  of  a 
bright  red  color  in  health,  but  pale  and  flaccid  in  disease, 
situated  at  the  inner  canthus,  between  the  lachrymal  ducts 
and  within  the  lacus  lachrymalis.  Its  structure  consists  of 
an  assemblage  of  minute  follicles  surrounded  by  a  dense 
fibro-cartilaginous  tissue;  it  furnishes  the  whitish  secre- 
tion so  often  seen  at  the  inner  canthus. 

Meibomian  glands,  (Fig.  103.) — These  are  situated  on  the 
posterior  surface  of  the  lids,  covered  by  the  tunica  conjunc- 
tiva, and  imbedded  in  grooves  of  FIG.  103. 
the  tarsal  cartilages.  They  are 
seen  as  strings  of  long  parallel 
ducts,  of  a  pale  yellow — about 
thirty  in  number  to  the  upper 
lid,  and  not  quite  so  many  to  the 
lower,  opening  on  the  margin  of 
each  lid,  by  a  row  of  minute  ori- 
fices, behind  the  cilia.  These  are 
visible  with  a  lens.  Each  Meibomian  gland  is  simply 
an  inflection  of  the  mucous  membrane,  forming  a  follicle 
which  is  extended  into  a  long  and  tortuous  tube,  having 
a  coacal  termination  surrounded  by  numerous  small  and 
clustered  follicles  which  open  into  it,  and  constitute  so 
many  offsets,  or  ccecal  diverticula. 

Function. — To  secrete  an  unctuous  fluid  which  lubricates 
the  margins  of  the  lids,  and  prevents  their  adhesion,  which 

FIG.  103  represents  the  Meibomian  glands.  1  Meibomian  glands  as  seen 
on  the  inner  side  of  the  lids.  2  Entrance  to  puncta  lachrymalis.  3  Carun- 
cula lachrymalis. 


358 


LACHRYMAL  APPARATUS. 


FIG.  104. 


sometimes  occurs  when  this  secretion  becomes  glutinous 
from  disease. 

Blood-vessels. — The  eyelids  are  supplied  with  arteries  by 
the  palpebral  branches  from  the  ophthalmic,  internally, 
and  by  the  facial,  transverse  facial,  and  infra  orbital,  ex- 
ternally and  inferiorly.  The  nerves  come  from  the  fifth 
and  the  facial. 

Lachrymal  Apparatus. — This  apparatus  (Fig.  104)  consists 
of  a  variety  of  parts— -first,  of  a  gland  to  secrete  the  tears ; 

second ,•  tubes  to  carry 
the  tears  to  the  eye; 
third,  puncta  lachry- 
malia  and  lachrymal 
ducts,  to  carry  this 
fluid  from  the  eye  into 
fourth,  the  lachrymal 
sac,  whence  it  reaches 
the  nose  by  fifth,  the 
nasal  duct.  The  lach- 
rymal belongs  to  the 
conglomerate  division 
of  glands,  and  is  situ- 
ated at  the  upper  and 
outer  angle  of  the  or- 
bit, occupying  the  lachrymal  fossa  in  the  orbital  plate  of 
the  frontal  bone. 

This  gland  is  of  a  pale  reddish  color,  consisting  of  two 
lobes,  a  superior  or  orbital,  and  an  inferior  or  palpebral, 
having  a  covering  of  cellular  structure.  The  orbital  is  the 
larger  portion,  being  about  three  quarters  of  an  inch  in 
length,  and  half  an  inch  in  breadth.  Its  upper  portion  is 
convex,  and  in  relation  with  the  periosteum  of  the  orbit ; 
its  lower  is  concave,  and  in  relation  with  the  superior  and 

FIG.  104  represents  the  Lachrymal  Apparatus,  a  Tarsal  cartilage  of  the 
upper  lid.  b  Tarsal  cartilage  of  the  lower  lid,  and  the  opening  along  the  mar- 
gins are  those  of  the  Meibomian  glands,  c  Caruncula  laehrymalis.  d  Lachry- 
mal gland,  e  Puncta  lachrymalia.  //  Lachrymal  ducts,  g  Lachrymal  sac. 
h  Nasal  duct,  i  Where  it  terminates  in  the  inferior  meatus  of  the  nose,  j 
Inferior  turbinated  bone. 


LACHRYMAL  APPARATUS.  359 

external  rectus  muscle.  The  palpebral  portion  is  smaller, 
lias  a  more  dense  capsule,  and  is  only  partially  separated 
from  the  orbital.  It  extends  down  as  far  as  the  orbital 
edge  of  the  cartilage  of  the  upper  lid. 

The  tears,  secreted  by  this  gland,  are  conveyed  away  by 
from  six  to  twelve  excretory  ducts  which  pass,  for  a  short 
distance  and  nearly  parallel  beneath  the  conjunctiva,  to 
the  upper  margin  of  the  tarsal  cartilage,  where  they  open 
by  separate  orifices,  in  a  curved  line  on  the  inner  surface 
of  the  upper  lid. 

Function. — To  secrete  the  tears  which  moisten  the  eye- 
lids and  the  eye.  The  tears  consist,  chemically,  of  water, 
and  about  one  per  cent,  of  muriate  of  soda,  and  a  yellow 
extractive  matter. 

Puncta  Lachrymalia,  (Fig.  104.) — These  are  two  small 
orifices,  situated  upon  the  papillary  eminence,  seen  at  the 
inner  extremity  of  each  ciliary  margin.  They  are  always 
open,  and  form  the  commencement  of  the  lachrymal  canals, 
which  are  one  to  each  eyelid,  proceeding  from  the  puncta. 
The  superior  is  longer  and  more  curved;  it  first  ascends, 
and  then  bends  suddenly  downward  and  inward  to  the 
sac,  entering  at  its  anterior  and  orbital  portion.  The  in- 
ferior canal,  at  first,  descends,  and  then  turns  abruptly 
inward  and  a  little  upward,  entering  the  sac  at  nearly 
the  same  point  with  the  upper  canal.  These  canals  consist 
of  dense  and  elastic  structure,  lined  by  mucous  membrane, 
and  have  the  tensor  tarsi  muscle  inserted  into  them. 

The  lachrymal  sac,  (Fig.  104,)  is  situated  in  the  groove 
of  the  os  unguis,  bounded  in  front  by  the  nasal  process  of 
the  superior  maxillary  bone.  It  consists  of  mucous  mem- 
brane, covered  by  a  strong  fibrous  expansion  from  the 
tendo  oculi,  which  tendon  crosses  it  transversely  a  little 
above  its  centre,  and  is  an  important  point  to  bear  in  mind 
in  opening  this  sac,  for  fistula  lachrymalis.  The  tensor  tarsi 
muscle  covers  its  orbital  surface.  On  opening  this  sac,  its 
lower  portion  is  found  constricted,  and  continuous  with  the 
nasal  duct ;  at  this  point  there  is  sometimes  found  a  semi- 
lunar  fold  or  valve,  separating  the  two.  The  interior  of 


360  THE  EAR. 

the  sac  is  of  a  pale  color  and  soft,  and  generally  found  filled 
with  mucus. 

The  nasal  duct  is  continuous  with  and  leads  from  the 
sac,  downward,  backward,  and  outward,  covered  by  the 
lower  turbinated  bone,  and  opening  into  the  inferior  mea- 
tus  of  the  nose  below.  It  is  a  short  canal,  about  three 
quarters  of  an  inch  in  length,  a  little  curved,  wider  at  the 
centre  than  at  either  end,  and  separated  from  the  antrum 
by  a  thin,  but  strong  bony  partition. 

Its  structure  is  fibre-mucous;  the  mucous  membrane 
continued  from  the  sac  and  lining  its  interior. 

Blood-vessels. — The  lachrymal  gland  is  supplied  by  the 
lachrymal  branch  of  the  ophthalmic  artery,  and  the  sac  by 
the  nasal  branch  of  the  same  artery. 

The  nerves  come  from  the  lachrymal  branch  of  the  oph- 
thalmic and  orbital  branch  of  the  superior  maxillary. 

Blood  vessels  and  Nerves  of  the  Eye  and  its  Appendages. — 
These  have  been  described  in  the  examination  of  the 
several  parts  composing  the  organ  of  vision,  and  we  only 
propose  making  a  single  remark  by  way  of  refreshing  the 
memory,  as  applicable  to  the  whole. 

The  ophthalmic  artery,  from  the  internal  carotid,  and  the 
facial,  temporal,  and  infra-orbital  from  the  external  carotid, 
are  the  great  sources  of  arterial  supply  to  the  apparatus  of 
sight.  The  nerves  come  from  the  second  or  optic,  the  third 
or  motor  oculi,  the  fourth  and  sixth  also  motor,  the  fifth 
and  seventh  pair,  and  from  sympathetic  branches.  See 
Figs.  73,  74  and  101. 

SECTION   II. 
THE  EAR. 

The  ear,  the  organ  of  hearing,  is  next  in  importance  of 
the  external  senses,  in  conveying  intelligence  to  the  mind; 
and  is  the  especial  organ  adapted  to  receive  the  impres- 
sions of  sound,  and  to  transmit  those  impressions  to  the 
sensorium. 

Just  as  we  have  seen  the  eye  to  have  special  relations  with 
light,  and  its  retina  or  nervous  expansion  to  be  sensible  to  all 


EXTERNAL  EAR. 


361 


the  varied  impressions  arising  from  the  different  varieties 
of  color,  and  its  optic  nerve  accurately  to  transmit  those 
impressions  to  the  brain  or  FIG.  105. 

mind;  so  in  the  ear  we  have  an 
organ  having  special  relation 
with  sound,  an  auditory  nerve, 
sensible  to  all  the  impressions 
of  the  varied  sonorous  vibra- 
tions, and  a  capacity  for  con- 
ducting those  impressions  to 
the  brain,  or  common  sensori- 
um,  where  perception  of  their 
presence  occurs,  and  where  the 
mind  forms  an  estimate  of  their 
value.  The  ear  is  usually  di- 
vided into  three  portions,  an 
external,  middle,  and  internal 
portion. 

The  external  ear,  (called  pinna  or  auricle?)  situated,  as  is 
well  known,  at  the  side  of  the  head,  and  between  the  mas- 
toid  and  squamous  portions  of  the  temporal  bone,  consists 
of  the  pinna  and  external  meatus. 

The  pinna  presents  a  number  of  eminences  and  depres- 
sions, forming  folds  and  hollows,  constituting  a  very  irregu- 
lar surface,  and  all  having  special  names  assigned  them. 
The  superior  folded  border  is  called  helix,  (f^t,  a  fold.)  The 
projecting  eminence  below  this  is  the  anti-helix.  The  de- 
pression between  the  two  is  called  the  fossa  innominata. 
The  pointed  projection  looking  backward  and  overhanging 
the  nieatus  as  a  valve,  is  called  the  tragus  (?payo$,  a  goat,) 
from  having  hairs  supposed  to  resemble  the  goat.  Just 
opposite  to  this  there  is  another  eminence  called  the  anti- 
tragus.  The  upper  extremity  of  the  anti-helix  divides  into 
two  crura,  leaving  a  triangular  space  between  them,  called 
scaphoid  or  navicular  fossa. 

FIG.  105  represents  the  external  Ear.  a  a  Helix.  666  Anti-helix,  c 
Scapha  or  fossa  navicularis.  d  d  Fossa  innominata.  e  Tragus.  /Antitragus. 
g  Lobulus.  h  Concha,  i  Meatus  auditorius  externus. 


362  EXTERNAL  EAR. 

All  the  depressions  and  furrows  of  the  pinna,  converge 
to  a  large,  central,  funnel-shaped  cavity,  the  concha, 
which  leads  obliquely  downward  and  forward  to  the  me- 
atus  auditorius  externus.  The  soft  and  pendulous  portion 
of  the  pinna,  at  its  lowermost  part,  is  named  the  lobulus. 

The  structure  of  the  pinna  consists  of  integument,  fibro- 
cartilage,  muscles ,  and  ligaments. 

The  integument  is  remarkable  for  its  strong  adhesion  to 
the  cartilage,  and  for  its  thinness  and  transparency.  The 
folding  of  the  skin  enclosing  fat  constitutes  the  lobule. 
The  skin  is  supplied  with  numerous  sebaceous  follicles, 
which  are  most  abundant  in  the  concha  and  scaphoid  fossa. 

The  fibro-cartilage  gives  the  shape  to  the  auricle,  forms 
the  framework  of  its  support,  and  is  the  source  of  its  elas- 
ticity and  pliability.  It  presents  very  nearly  the  same 
eminences  and  depressions  as  those  already  described.  The 
lobule  is  without  the  cartilage.  This  cartilage  is  covered 
with  perichondrium,  which  becomes  weak  and  brittle  on 
being  removed.  The  tragus  is  separated  from  the  helix  by 
fibrous  tissue,  and  presents  a  deep  fissure.  A  considerable 
fissure  separates  the  termination  of  the  helix  and  anti- 
helix  from  the  concha. 

The  muscles  of  the  external  ear  consist  of  those  which 
attach  it  to  the  head,  and  of  those  passing  from  one  car- 
tilage to  the  other.  The  first  division  comprises  three 
muscles,  the  superior  or  attollens  aurem}  the  anterior  or 
attrahens  aurem,  and  the  posterior  or  retraliens  aurem, 

(fig-  82.) 

The  attollens  aurem  is  a  triangular  muscle,  the  largest  of 
the  three,  and  arises,  broad  and  tendinous,  from  the  cra- 
nial aponeurosis  above  the  ear ;  it  descends,  becomes  fleshy, 
and  is  inserted  into  the  upper  and  anterior  part  of  the 
concha. 

Function. — To  raise  the  external  ear,  and  deepen  the 
meatus. 

Anterior  auris,  also  triangular,  arises  from  the  posterior 
part  of  the  zygomatic  process  and  cranial  aponeurosis,  and 
is  inserted  into  the  anterior  part  of  the  helix. 


EXTERNAL  EAR.  363 

Function. — To  bring  the  ear  forward.  This  muscle  rests 
upon  the  temporal  vessels,  nerves,  and  fascia. 

Posterior  auris,  arises  from  the  mastoid  process  by  two 
or  three  fasciculi,  and  is  inserted  into  the  back  part  of  the 
concha.  Function. — To  draw  the  ear  backward  and  en- 
large the  meatus. 

The  proper  or  intrinsic  muscles  of  the  external  ear  re- 
ceive their  names  from  the  prominences  to  which  they  are 
attached,  as  the  major  lielicis,  minor  Jielicis,  tragicus,  anti- 
tragicuSj  transversus  auriculce. 

Major  helicis  is  a  small  band  of  muscular  fibres  lying 
upon  the  superior  border  of  the  helix. 

Minor  helicis  is  below  the  last,  and  posterior  upon  the 
helix,  at  its  commencement  in  the  concha. 

The  Tragicus  covers  the  cartilage  of  the  tragus. 

The  Anti-tragicus  reaches  from  the  anti-tragus  to  the 
posterior  part  of  anti-helix. 

Transversus  auriculae,  situated  on  the  posterior  surface  of 
the  pinna,  'extends  transversely  from  the  concha  to  the 
helix.  These  muscles  are  very  feeble  in  man,  and  scarcely 
to  be  recognized;  but  in  most  quadrupeds  they  are  well 
developed,  and  capable  of  altering,  with  ease  and  rapidity, 
the  form  and  direction  of  the  auricle. 

Meatus  auditorius  externus  is  a  tube  extending  from  the 
lower  part  of  the  concha,  inward  to  the  membrana  tym- 
pani.  It  is  about  an  inch  and  a  quarter  in  length,  and 
has  its  external  half  cartilaginous — the  remainder  osseous. 
Its  direction  is  curved,  leading  first  forward  and  upwarfl, 
then  backward;  and  by  pulling  the  ear  backward  and 
upward,  the  canal  can  be  straightened,  and  the  membrana 
tympani  seen.  The  upper  and  posterior  part  of  the  meatus 
consists  of  dense  fibro-celliilar  tissue,  extending  from  the 
concha  to  the  osseous  part  of  the  canal.  The  osseous  por- 
tion of  the  meatus  in  the  child  is  simply  a  bony  ring,  and 
is  much  shorter.  In  the  adult,  it  forms  the  anterior  and 
inferior  walls  of  the  meatus  externus,  and  also  an  investing 
sheath  to  the  styloid  process,  being  separated  from  the 
glenoid  cavity,  by  the  fissure  of  Glasser. 


364  MIDDLE  EAR. 

The  external  opening  of  the  meatus  is  of  oval  form ;  of 
variable  size,  and  often,  in  old  people,  containing  coarse 
hairs,  which  prevent  the  entrance  of  insects  and  foreign 
bodies. 

The  meatus  is  lined  by  the  skin  continued  from  the 
auricle — it  becomes,  however,  very  thin,  vascular,  and  sen- 
sitive, and  set  with  delicate  hairs.  Beneath  it  are  seen 
numerous  follicles,  which  appear  upon  its  surface  by  many 
orifices,  and  are  called  ceruminous  glands.  These  glands 
are  little  oval  bodies,  of  a  pale  yellow,  having  a  tortuous 
ccecal  tube ;  they  secrete  the  cerumen  or  wax  of  the  ear. 

This  secretion  is  a  viscid  matter,  intensely  bitter,  at  first 
soft,  but  soon  becoming  solid,  and  designed  to  defend  the 
meatus  from  foreign  intrusion. 

The  ligaments  of  the  pinna  are  the  anterior,  which  con- 
nects the  tragus  and  anterior  part  of  the  helix  to  the  root 
of  the  zygoma;  and  the  posterior,  connecting  the  concha  to 
the  mastoid  process.  Some  fibres,  extending  from  one  em- 
inence to  another,  are  also  spoken  of  as  ligaments. 

The  Arteries  of  the  external  ear  come  from  the  posterior 
auricular  of  the  external  carotid,  and  the  anterior  auricu- 
lar of  the  temporal. 

The  Nerves  are  supplied  by  auricular  branches  from  the 
cervical  plexus,  and  the  fifth.  At  the  anti-tragus  a  branch 
perforates  the  meatus,  and  is  distributed  upon  the  inner 
surface  of  the  concha. 

Middle  Ear,  or  Tympanum. — Dissection. — Kemove  the 
membrana  tympani,  or  cut  away  the  anterior  part  of  the 
base  of  the  petrous  .portion  of  the  temporal  bone,  and  the 
tympanum  will  be  exposed.  The  tympanum  (tympanum,  a 
drum)  is  a  small  cavity  of  irregular  form,  situated  between 
the  meatus  externus  and  the  labyrinth  or  internal  ear, 
having  the  mastoid  portion  of  the  temporal  bone  behind, 
and  communicating,  in  front,  with  the  Eustachian  tube. 

Its  external  boundary  is  the  membrana  tympani,  or  drum 
of  the  ear.  This  membrane,  situated  at  the  bottom  of  the 
meatus,  is  of  a  circular  form,  and  directed  obliquely  down- 
ward and  inwardj  in  such  way  that  the  inferior  wall  is 


MIDDLE  EAR. 


365 


FIG.  106. 


longer  than  the  superior.  Its  circumference  is  fitted  like 
a  watch-glass  into  the  circular  furrow  in  the  base  of 
the  meatus,  in  the  adult,  and  into  the  tympanic  ring  of 
the  foetus.  It 
is  a  thin,  semi- 
transparent, 
dry,  parch- 
ment-like mem- 
brane, and  con- 
sists of  three 
layers,  an  ex- 
ternal or  cuta- 
neous, already 
described,  a 
middle,  or  fi- 
brous, and  an 
internal  or  mu- 
cous. 

The  middle  layer  forms  the  membrane  proper  of  the 
the  drum,  and  gives  the  form  and  strength  to  this  septum 
between  the  meatus  and  tympanum.  It  is  fibrous,  and  the 
fibres  are  seen  radiating  from  the  circumference  to  the 
centre,  where  the  malleus  is  attached.  Mr.  E.  Home,  from 
the  examination  of  this  membrane  in  an  elephant,  was  led 
to  regard  its  structure  as  muscular,  which  opinion,  how- 
ever, is  not  generally  adopted.  The  internal  layer  is  the 
continuation  of  the  mucous  membrane  from  the  pharynx 
into  the  Eustachian  tube  and  the  cavity  of  the  tympanum. 
The  membrana  tympani  is  capable  of  injection  and  presents 
a  beautiful  arrangement  of  radiated  and  delicate  vessels. 
It  is  formed  for  vibrating,  and  its  function  is  to  receive  the 
sonorous  undulations  from  the  air,  and  transmit  them  to  the 
chain  of  little  bones,  in  the  tympanum,  connected  with  it. 

The  internal  boundary  of  the  tympanum  presents  a  bony 

FIG.  106  represents  the  external,  middle,  and  internal  Ear.  a  External 
ear.  &  Meatus  auditorius  externus.  c  Membrana  tympani.  d  Malleus,  e 
Incus.  /  Cavity  of  the  tympanum,  g  Stapes,  h  Semi-circular  canals,  t 
Auditory  nerve,  j  Cochlea,  k  Eustachian  tube. 


366  MIDDLE  EAR. 

projection  called  the  promontory,  above  this  projection  is 
the  foramen  ovale  or  fenestra  ovalis,  below  it  is  the  foramen 
rotundum  or  fenestra  cochlece. 

The  fenestra  ovalis  is  situated  directly  opposite  the  mem- 
brana  tyrnpani,  is  of  an  oval  shape,  and  leads  into  the  ves- 
tibule. In  the  living  subject  it  is  closed  by  a  membrane  to 
which  the  base  of  the  stapes  is  attached.  This  membrane, 
like  the  tympanic,  consists  also  of  three  layers,  the  lining 
of  the  tympanum,  the  lining  of  the  vestibule,  and  its  proper 
and  intermediate  layer  of  fibrous  tissue. 

The  foramen  rotundum  leads  into  the  cochlea,  and  is 
closed  by  a  similar  membrane. 

The  promontory  corresponds  to  the  first  turn  of  the 
cochlea,  and  has  upon  its  surface  three  grooves,  which 
converge  into  a  common  canal,  opening  on  the  inferior  sur- 
face of  the  petrous  bone,  between  the  foramen  caroticum  and 
foramen  lacerum  posticum,  containing  a  branch  of  the  glosso- 
pharyngeal,  called  Jacobson's  nerve. 

Posterior  to  the  fenestra  ovalis  is  a  hollow  process  called 
the  pyramid,  containing  the  small  stapedius  muscle. 

The  anterior  wall  contains  the  opening  of  the  Eustachian 
tube.  This  tube  is  a  very  important  structure,  and  is  sit- 
uated between  the  tympanum  and  the  pharynx.  It  is  from 
an  inch  and  a  half  to  two  inches  in  length,  passing  from 
the  cavity  of  the  tympanum,  forward,  downward  and  in- 
ward, to  the  posterior  nares,  above  the  velum  palati,  above 
and  behind  the  lower  meatus  of  the  nose,  and  on  a  level 
with  the  inferior  turbinated  bone,  opening  on  the  sides  of 
the  pharynx,  in  a  large,  trumpet-like  orifice,  sufficient  to 
admit  the  end  of  the  little  finger. 

The  structure  of  this  tube  consists  of  bone,  cartilage, 
fibrous  and  mucous  tissues. 

The  bony  portion,  about  seven  lines  in  length,  is  situated 
in  the  angle  between  the  squamous  and  petrous  bones,  and 
connected  with  the  tympanum.  It  is  attached  to  the  groove 
between  the  spinous  process  of  the  sphenoid  and  petrous 
bones,  leading  to  the  root  of  the  internal  pterygoid  process. 
Its  internal  or  pharyngeal  portion  is  cartilaginous.  The 


MIDDLE  EAR.  36*7 

outer  wall  is  composed  partly  of  cartilage  and  partly  of 
fibrous  tissue,  covered  by  the  tensor  palati  muscle.  This 
tube,  where  it  opens  into  the  pharynx,  is  thick,  and  pre- 
sents a  division  into  two  angles,  the  anterior  being  con- 
nected by  fibrous  tissue  to  the  root  of  the  internal  ptery- 
goid  plate ;  the  posterior  thick,  prominent,  and  admitting 
of  motion.  Its  mucous  tissue  forms  the  internal  lining, 
and  is  continuous  with  that  of  the  pharynx,  and  also  with 
that  of  the  tympanum.* 

Function. — To  give  passage  to  the  air  into  the  tympanum, 
and  to  conduct  the  secretions  from  the  tympanum  to  the 
fauces.  Obstructions  in  this  tube,  from  inflammation  and 
other  causes,  are  frequent  sources  of  deafness.  Above  the 
Eustachian  tube,  and  separated  by  a  thin  osseous  plate,  is  a 
canal  for  the  attachment  of  the  tensor  tympani  muscle. 

The  posterior  wall,  at  its  upper  part,  has  an  opening  lead- 
ing into  the  mastoid  cells,  which,  like  the  tympanum,  are 
found  to  contain  air,  and  are  lined  with  mucous  membrane. 
Beneath  this  mastoid  orifice  is  a  small  opening  from  the 
aqueduct  of  Fallopius,  transmitting  the  chorda  tympani 
nerve. 

The  superior  wall  presents  a  depression  for  the  head  of 
the  malleus,  and  the  body  and  short  leg  of  the  incus,  It  is 
spongy,  and  has  some  small  vessels  passing  through  it  to 
the  dura  mater. 

The  inferior  wall  is  rough  and  narrow,  formed  by  the 
auditory  and  vaginal  processes.  It  has  a  small  opening 
which  gives  exit  to  the  chorda  tympani  nerve  from  the 
cavity  of  the  tympanum. 

The  tympanum   contains  a  chain  of  little  bones,   the 

*  Muscles  of  Eustachian  Tube. — Joseph  Toynbee,  F.  R.  S.,  believes  he  has  de- 
monstrated that  the  mouth  of  the  Eustachian  tube  is  always  closed,  except 
during  deglutition;  and  that  the  cavity  of  the  tympanum  is  always  "  distinct 
and  isolated  from  the  outer  air,"  except  in  deglutition.  The  muscles  which 
open  this  tube,  he  says,  are  the  tensor  and  levator  palati;  and  he  further  states 
that  the  function  of  hearing  is  best  carried  on  when  the  tympanum  is  closed, 
entirely  upsetting  the  opinion  that  the  air  within  the  tympanum  must  commu- 
nicate with  the  outer  air  in  the  pharynx,  that  vibration  may  take  place,  and 
hearing  be  produced.— »2mer.  Jour.  Medical  Science,  Jlpril  JVb.,  1853. 


368  MIDDLE  EAR. 

ossicula  audituSj  stretching  across  its  cavity  from  the  mem- 
brana  tympani  to  the  fenestra  ovalis.  They  are  four,  the 
malleus,  incus,  os-orbiculare,  and.  stapes ,  (Fig.  107.) 

The  malleus,  so  called  from  its  resemblance  to  a  hammer, 
is  the  first  in  order  behind  the  membrana  tympani,  and  is 
FlG-  1Q7-  connected  with  it.  It  consists  of  a  head,  neck, 
handle,  a  long  and  short  process.  The  head 
is  situated  in  the  depression  on  the  upper  part 
of  the  tympanum,  and  is  smooth  and  round 
above,  and  concave  below  for  articulating  with 
the  incus.  Below  the  head  is  the  constricted 
portion  called  the  neck — -from  this  the  long  and 
short  processes  arise.  The  long  one  called  the 
processus  gracilis  or  process  of  Kau,  is  a  slender 
thorn-like  process,  proceeding  from  the  ante- 
rior part  of  the  neck.  It  enters  the  Glasserian 
fissure,  and  gives  attachment  to  the  laxator  tympani  mus- 
cle, which  is  thought  to  be  more  properly  a  ligament.  The 
short  process  is  external,  and  rests  against  the  upper  part 
of  the  membrana  tympani.  The  handle  (manubrium)  de- 
scends almost  vertically  from  the  neck,  as  low  as  the  centre 
of  the  membrana  tympani,  to  the  radiating  fibres  of  which 
it  is  strongly  attached. 

The  incus,  (or  anvil,)  Fig.  10*7,  is  posterior  to  the  mal- 
leus, and  has  been,  not  inaptly,  compared  to  a  bicuspid 
tooth.  It  consists  of  a  body  and  two  crura.  The  body  re- 
ceives the  head  of  the  malleus,  and  lies  in  the  depression  of 
the  tympanum.  The  superior  or  short  crus  proceeds  horizon- 
tally backward  and  is  found  in  the  opening  of  the  mastoid 
cells.  The  inferior  or  long  crus  'descends  vertically  into 
the  cavity  of  the  tympanum,  having  the  chorda  tympani 
between  it  and  the  handle  of  the  malleus,  and  terminates 
in  a  hook-like  process,  which  has  on  its  extremity  a  small 
round  tubercle,  the  os-orbiculare. 

The  Stapes,  (Fig.  107,)  so  called  from  its  resembling  a 
stirrup-iron,  is  situated  between  the  fenestra  ovalis,  and  the 

FIG.  107  represents  the  Ossicles  or  Little  Bones  of  the  Ear,  separately  and  of 
the  natural  size,    a  Malleus.    6  Incus,    c  Os-orbiculare.    d  Stapes. 


MIDDLE  EAR.  369 

os-orbiculare.  It  consists  of  a  head,  neck,  base,  and  two 
crura.  Its  head  is  hollow  for  receiving  the  os-orbiculare. 
The  neck  gives  attachment  to  the  stapedius  muscle.  The 
base  is  a  flat,  oval-shaped  plate,  like  the  foot  of  the  stirrup, 
and  is  attached  to  the  membrana  vestibuli.  The  two  crura 
or  branches  extend  between  the  neck  and  base. 

These  little  bones  are  connected  together  by  regular 
articulations,  having  synovial  membranes,  and  capsular 
ligaments ;  with  an  additional  security  of  three  other  liga- 
ments— one  going  from  the  head  of  the  malleus,  to  the 
superior  wall  of  the  tympanum ;  a  second  connecting  the 
short  process  of  the  incus  with  the  mastoid  cells ;  the  third, 
a  circular  ligament,  surrounding  the  margin  of  the  fenestra 
ovalis,  and  connecting  it  with  the  base  of  the  stapes. 

Muscles  of  the  Tympanum. — Anatomists  are  not  agreed 
as  to  the  number  of  these  muscles — some  making  four, 
others  three,  and  others  two;  the  discrepancy  arising  from 
one  or  two  of  these  muscles  being  considered  as  ligaments. 
The  membrana  tympani  has  two  muscles — a  tensor  and  a 
laxator. 

Tensor  Tympani  (or  internal  muscle  of  the  malleus) 
arises  from  the  Eustachian  tube,  the  spinous  process  of  the 
sphenoid  bone,  and  from  the  petrous  portion  of  the  tempo- 
ral. It  has  distinct  fleshy  fibres,  which  are  lodged  in  the 
canal  above  the  Eustachian  tube,  and  entering  the  tympa- 
num at  its  forepart,  are  inserted  into  the  handle  of  the  mal- 
leus below  the  processus-gracilis.  Function. — To  draw  the 
handle  inward,  and  thus  make  tense  the  membrana  tympani. 

Laxator  Tympani  (or  external  muscle  of  the  malleus) 
arises  from  the  spinous  process  of  the  sphenoid  bone — goes 
through  the  glenoid  fissure,  and  is  inserted  into  the  pro- 
cessus  gracilis.  Function. — To  relax  the  membrana  tym- 
pani. This  muscle  is  often  found  to  be  only  a  ligament. 

Laxator  Tympani  Minor  is  also  regarded  as  simply  a 
ligament  of  fibrous  cord,  extending  from  the  handle  of  the 
malleus,  below  the  short  process,  to  the  upper  margin  of 
the  rneatus. 

Stapedius. — This  little  muscle,  which  has  been  also 
24 


370  INTERNAL  EAR  OR  LABYRINTH. 

thought  to  resemble  a  ligament,  arises  within  the  hollow 
of  the  pyramid,  and  is  inserted  into  the  neck  of  the  stapes. 

Function. — By  pressing  the  base  of  the  stapes  against 
the  fenestra  ovalis;  and  thus  drawing  the  bony  chain  in- 
ward, it  has  been  supposed  to  act  as  a  tensor  upon  the 
membrana  tympani. 

Lining  Membrane  of  Tympanum. — It  has  already  been 
stated  that  this  membrane  is  mucous,  and  continuous  with 
that  of  the  pharynx  and  Eustachian  tube ;  but  in  the  tym- 
panum it  is  much  more  delicate,  and  closely  united  to  the 
periosteum,  so  as  to  be  considered  a  fibro-mucous  mem- 
brane. It  covers  all  the  inner  walls  of  the  tympanum — is 
reflected  round  the  muscles,  nerves,  and  bones — lines  the 
tympanic  surfaces  of  the  membrana  tympani,  membrana 
vestibuli,  membrana  rotunda,  and  the  space  between  the 
crura  of  the  stapes,  and  is  continued  into  the  mastoid  cells. 

INTERNAL  EAR   OR  LABYRINTH. 

The  internal  ear  or  labyrinth,  so  called  from  the  intricacy 
of  its  internal  arrangement,  is  situated  on  the  inner  side 
of  the  tympanum,  and  deep  within  the  petrous  portion  of 
the  temporal  bone.  This  is  the  essential  part  of  the  organ 
of  hearing,  and  consists  of  the  vestibule,  cochlea,  and  semi- 
circular canals. 

The  vestibule  occupies  the  centre  of  the  labyrinth,  being 
situated  between  the  tympanum  and  meatus  auditorius  in- 
ternus,  having  the  cochlea  in  front,  and  the  semicircular 
canals  behind.  It  has  three  dilatations,  called  cornua  or 
ventricles  ;  one  superior,  one  anterior,  and  the  third  posterior. 
The  superior  receives  two  openings  of  the  semicircular 
canals,  the  posterior  the  other  openings  of  the  canals,  while 
the  anterior  opens  into  the  scala  of  the  cochlea.  The  inner 
wall  of  the  vestibule  is  cribriform  and  corresponds  to  the 
base  of  the  meatus  internus,  transmitting  some  fine  ves- 
sels, and  fibrillee  of  the  auditory  nerve.  On  the  posterior 
wall  there  is  a  foramen  called  the  aqueduct  of  the  vestibule, 
which  opens  on  the  posterior  surface  of  the  petrous  bone. 
behind  the  meatus  internus. 


IXTERXAL  EAR  OR  LABYRINTH. 


371 


The  meatus  internus  has  elsewhere  been  stated  to  be  sit- 
uated on  the  posterior  cerebral  surface  of  the  petrous  bone. 
It  is  lined  by  dura  mater,  and  Fio.  108.  A 

has  a  depth  of  about  one  quarter 
of  an  inch.  Its  bottom  pre- 
sents a  cul  de  sac  or  cribriform 
plate,  divided  by  a  bony  crest 
into  two  portions,  the  superior 
has  a  large  opening,  the  aqueduct 
of  FallopiuSj  for  transmitting' 
the  facial  nerve,  and  some  small 
foramina  which  open  into  the 
vestibule.  The  lower  portion 
corresponds  to  the  base  of  the 
cochlea,  and  is  perforated  by 
many  foramina ;  a  part  of  this 
inferior  depression  has  apertures 
also  leading  into  the  vestibule.  It  is  through  the  cribri- 
form base  of  the  meatus  internus  that  the  labyrinth  is 
supplied  with  its  nerves  and  most  of  its  vessels.  The  an- 
terior corner  of  the  vestibule  has  a  depression  called  fovea 
hemispherica;  and  another  above  this,  the  fovea  elliptica. 

The  Cochlea,  so  called  from  its  resemblance  to  a  snail 
shell,  is  situated  in  the  anterior  part  of  the  petrous  bone. 
Its  form  is  conical,  its  apex  being  directed  forward,  while 
its  base  corresponds  with  the  bottom  of  the  internal  audi- 
tory meatus.  It  consists  of  a  narrowing  tube,  divided  by  a 
partition  extending  from  the  base  to  the  apex,  into  two 
tubes,  and  coiled  round  a  central  pillar.  The  tube  of  the 
cochlea  is  described  as  being  about  one  inch  and  a  half 
in  length,  one  tenth  of  an  inch  in  diameter  at  its  base,  and 

FIG.  108,  A  represents  the  Labyrinth  of  the  Ear  laid  open,  a  Fovea 
elliptica.  b  Fovea  hemispherica.  c  Common  entrance  of  the  posterior  and 
superior  semi-circular  canals,  d  Opening  of  the  aqueduct  of  the  vestibule. 
e  Superior  semi-circular  canal.  /  Posterior,  g  Inferior  semi-circular  canal. 
h  Spiral  canal  of  the  cochlea,  i  Opening  of  tthe  aqueduct  of  the  cochlea, 
j  Lamina  spiralis. 

Fio.  108,  B  Cochlea  laid  open,  a  Modiolus.  6  Lamina  spiralis.  c  Scala 
tympani.  d  Scala  vestibuli. 


372  INTERNAL  EAR  OR  LABYRINTH. 

about  one-twentietli  at  its  summit.  It  makes  a  spiral  coil 
of  two  turns  and  a  half  around  a  central  axis  or  modiolus, 
and  is  compared  to  a  winding  stair-case.  It  is  separated  by 
a  partition,  called  lamina  spiralis,  into  two  tubes,  named 
scalce,  (scala,  a  stair-case.)  The  lamina  spiralis  consists  of 
s  an  osseous  and  membranous  portion.  The  osseous  forms 
the  inner  portion,  being  in  contact  with  the  modiolus,  round 
which  it  winds.  It  is  broader  at  the  base  and  gradually 
diminishes  to  the  apex,  where  it  ends  in  a  hook  called  the 
hamulus.  The  membranous  part  of  the  lamina  completes 
the  outer  portion  of  the  septum  and  is  attached  to  the  inner 
surface  of  the  tube  of  the  cochlea,  it  is  the  converse  of  the 
osseous  plate,  and  is  broader  above  than  below,  where  it 
forms  the  entire  septum. 

Both  the  osseous  and  membranous  portions  of  the  lamina 
spiralis  consist  of  two  thin  plates,  leaving  a  space,  in  which 
the  cochlear  nerves  and  vessels  are  distributed.  This 
lamina  spiralis  or  septum  of  the  tube  of  the  cochlea,  divides 
the  tube  into  the  scalce. 

The  Scalce  are  two  in  number — the  one  communicating 
with  the  vestibule  called  scala  vestibuli — the  other,  with 
the  tympanum,  named  the  scala  tympani.  These  scalas  are 
separated  throughout  their  whole  extent,  except  at  the 
summit  of  the  cochlea,  over  the  hamulus,  where  they  com- 
municate by  one  common  opening.  The  scala  vestibuli  is 
external  and  superior — while  the  scala  tympani  is  internal 
and  inferior. 

The  Modiolus  constitutes  the  central  axis,  or  pillar  of  the 
cochlea,  extending  from  its  base  to  its  apex,  around  which 
both  the  tube  and  spiral  lamina  make  their  turns.  It  arises 
from  the  bottom  of  the  internal  auditory  meatus,  as  a  bony 
process,  forming  a  conical  tube  which  proceeds  horizontally 
outward,  and  contracts  as  it  reaches  the  apex.  The  base  of 
the  modiolus  is  perforated  with  foramina,  for  the  passage 
of  the  auditory  nerves.  Its  funnel-shaped  summit  is  called 
the  infundibulum,  and  is  arched  over,,  or  surmounted  by  the 
blind  apex  of  the  tube  of  the  cochlea,  named  the  cupola. 
The  surface  of  the  modiolus  presents  numerous  canals 


INTERNAL  EAR  OR  LABYRINTH.  373 

which  open  by  foramina,  corresponding  to  similar  canals 
on  the  lamina  spiralis,  for  transmitting  the  auditory  ves- 
sels and  nerves.  One  of  these  canals,  larger  than  the  rest, 
the  tubulus  centralis  modioli,  passes  on  to  the  infundibulum, 
and  conducts  the  terminal  branch  of  the  cochlear  nerve, 
and  the  arteria  centralis  modioli. 

The  aqueduct  of  the  cochlea  extends  from  the  scala  of  the 
tympanum,  into  which  it  opens,  near  the  fenestra  rotunda, 
to  the  lower  surface  of  the  petrous  bone  near  the  jugular 
fossa — like  the  aqueduct  of  the  vestibule,  it  simply  carries 
a  vein,  and  is  closed  by  the  dura  mater. 

Semicircular  Canals,  (Fig.  108.) — These  consist  of  three 
bony  tubes,  representing  so  many  cylinders  of  equal  diam- 
eters, and  forming  about  three-fourths  of  a  circle.  They 
are  situated  within  the  substance  of  the  petrous  bone  be- 
hind the  vestibule,  into  which  they  open  by  five  distinct 
orifices.  Two  of  these  canals  are  perpendicular,  and  the 
third  horizontal.  They  are  the  anterior  and  superior  ver- 
tical, posterior  and  inferior  vertical,  and  the  horizontal. 

The  superior  vertical  makes  a  projection  on  the  upper 
surface  of  the  petrous  bone — crosses  it  transversely,  its 
outer  extremity  opening,  by  an  ampulla,  into  the  superior 
cornu  of  the  vestibule — while  its  inner  unites  with  the 
upper  crus  of  the  posterior  vertical,  forming  a  common 
tube,  which  enters,,  by  a  single  orifice,  into  the  posterior 
cornu  of  the  vestibule. 

The  posterior  vertical  canal  is  at  right  angles  to  the  su- 
perior, and  parallel  to  the  posterior  surface  of  the  petrous 
bone.  It  opens,  by  one  extremity,  into  the  posterior  cornu ; 
and  by  the  other  it  forms,  with  one  end  of  the  superior,  a 
common  canal,  opening  also  into  the  same  cornu  of  the 
vestibule. 

The  horizontal  is  the  shortest  of  the  canals,  and  enters, 
by  an  ampulla  at  one  end,  into  the  superior  cornu ;  and  at 
the  other  end,  into  the  posterior  cornu  of  the  vestibule. 
The  semicircular  canals  are  thus  seen  to  have,  each  at  one 
)f  their  extremities,  a  dilatation  or  ampulla — one  at  the 
•uter  end  of  the  superior  vertical,  one  at  the  inferior 


3*74  INTERNAL  EAR  OR  LABYRINTH. 

end  of  the  posterior,  and  one  at  the  anterior  end  of  the 
horizontal. 

Membrane  lining  tlie  Labyrinth. — This  membrane  is  fibro- 
serous,  and  is  to  be  distinguished  from  another  to  be 
presently  described,  called  the  membranous  labyrinth.  It 
resembles  the  dura  mater  in  having  an  external  and  fibrous 
layer,  acting  the  part  of  periosteum,  and  adhering  to  the 
bone,  while  its  internal  is  free,  smooth,  and  serous,  se- 
creting a  fluid  called  the  liquor  Cotunnii,  perilympli,  or 
aqua  labyrinthi.  This  membrane  lines  the  vestibule,  coch- 
lea, and  semicircular  canals;  and  also  the  fenestra  ovalis, 
and  rotunda.  The  lamina  spiralis  also  gets  a  covering 
from  it  on  either  surface;  and  these  two  layers,  coining 
together  at  the  free  external  margin  of  the  osseous  lamina, 
pass  to  the  outer  wall  of  the  tube,  and  thus  complete  the 
septum  between  the  two  scalar  It  also  sends  processes  into 
the  aqueducts  of  the  vestibule  and  cochlea. 

The  membranous  labyrinth  does  not  enter  the  cocKlea, 
and  is  not  so  extensive  as  the  osseous,  though  it  has  the 
same  form.  It  consists  of  four  layers — an  external  serous, 
a  vascular,  a  nervous,  and  an  internal  serous  layer;  thus 
constituting  a  tube  which  floats  between  two  fluids — the 
outer,  the  perilymph,  or  liquor  of  Cotunnius,  secreted  by  the 
external  serous  layer,  and  separating  it  from  the  walls  of 
the  osseous  labyrinth;  and  the  inner,  the  liquor  of  Scarpa, 
or  endolympli,  contained  within  the  membranous  tube  of  the 
labyrinth  itself,  and  secreted  by  its  internal  serous  layer. 

The  membranous  labyrinth  contains  two  sinuses,  and 
three  membranous  semicircular  canals.  The  sinuses  are 
the  common  sinus,  or  vestibular  ventricle,  and  the  sacculus 
proprius,  or  vestibuli.  The  common  sinus  is  in  the  poste- 
rior part  of  the  vestibule,  and  receives  the  openings  of  the 
five  semicircular  canals.  It  is  distended  by  the  liquor  of 
Scarpa,  and  floats  in  the  fluid  of  Cotunnius. 

The  sacculus  proprius  is  situated  anteriorly  and  inferi- 
orly  to  the  common  sinus;  it  is  round,  and  much  smaller; 
but  it  is  not  settled  whether  the  two  have  any  communica- 
tion, though  they  are  in  close  contact. 


INTERNAL  EAR  OR  LABYRINTH. 


375 


The  membranous  semicircular  canals,  as  lias  been  stated, 
are  much  smaller  than  the  osseous  tubes  in  which  they  are 
situated,  have  the  the  same  form,  and  present  the  same 
number  of  ampullae.  They  are  likewise  distended  with  the 
fluid  of  Scarpa,  and  separated  from  the  osseous  semicircular 
walls,  by  the  fluid  of  Cotunnius. 

In  the  sacculus  communis,  and  proprius  of  the  vestibule, 
Breschet  discovered  two  white,  shining  masses,  composed 
of  phosphate  and  carbonate  of  lime,  held  together  by  ani- 
mal matter.  Being  in  the  form  of  powder,  or  dust,  he 
called  them  otoconia,  (01^,  the  ear,  and  songs  dust.)  This 
ear-dust,  or  calcareous  matter,  floats  in  the  fluid  of  Scarpa. 

Nerves  of  the  Ear. — The  nerves  of  the  ear  come  from  the 
seventh,  the  fifth,  the  eighth  pair — the  cervical  plexus, 
and  the  sympathetic.  The  portio  mollis  of  the  seventh 
pair  is  the  especial  nerve  of  hearing,  entering  the  in- 
ternal auditory  me-  FIG.  109. 
atus.  It  divides,  at 
the  cribriform  base 
of  this  meatus,  into 
two  branches — the 
anterior  and  larger, 
going  to  supply  the 
cochlea,  and  the  pos- 
terior and  smaller, 
passing  to  the  vesti- 
bule and  semicircu- 
lar canals. 

The  anterior,  or 
coclilear  branch,  has 
a  spiral  direction,  and  has  been  compared  to  a  flat  tape, 
rolled  on  itself.  At  the  base  of  the  meatus  internus  it 
enters  the  foramina,  in  the  tractus  spiralis,  by  numerous 
minute  filaments  which  spread  out  upon  the  surface  of  the 

FIG.  109  represents  the  Labyrinth,  laid  open  and  inverted,  so  as  to  show 
the  distribution  of  its  nerves,  a  6  c  Cochlea  laid  open,  d  ef  Remains  of  the 
parietes  of  the  cochlea,  g  h  Vestibule,  i  i  Superior  semicircular  canal,  kl 
Inferior  or  horizontal  canal,  m  Posterior  canal,  n  n  Semicircular  mem- 
branous canals,  op  q  Auditory  nerves  passing  to  the  labyrinth. 


376  INTERNAL  EAR  OR  LABYRINTH. 

modiolus,  and  between  the  plates  of  the  lamina  spiralis. 
The  posterior  branch  divides  into  the  superior,  middle,  and 
inferior.  The  superior  filaments  enter  the  vestibule  through 
the  small  foramina  of  the  pyramid,  and  are  expanded  on 
the  sacculus  communis,  and  ampullce  of  the  superior  verti- 
cal, and  horizontal  membranous  canals.  The  middle  set 
supply  the  sacculus  proprius,  and  the  inferior  go  to  the 
ampulla  of  the  posterior  vertical  semicircular  canals.  The 
auditory  nerve  is  remarkable  for  its  softness,  and  for  its 
numerous  divisions  into  minute  branches,  which  anasto- 
mose together,  and  form  an  exceedingly  delicate  nervous 
membrane,  having,  according  to  some,  the  papillary  form 
of  termination. 

The  Vidian  nerve  bestows  common  sensibility,  and  coming 
from  Meckel's  ganglion  belongs  to  the  second  division  of  the 
fifth.  Entering  the  hiatus  Fallopii,  it  joins  the  portio  dura 
of  the  seventh  in  the  aqueduct  of  Fallopius,  and  after  a  short 
distance,  leaves  it  to  enter  the  tympanum,  and  through  a 
small  foramen  posterior  to  the  pyramid.  In  this  cavity  it 
is  called  chorda  tympani,  and  sends  branches  to  the  tym- 
panic plexus ;  passes  between  the  handle  of  the  malleus  and 
long  leg  of  the  incus,  and  escapes  at  the  fissure  of  Glasser. 

The  portio-dura  is  a  motor  nerve  and  supplies  the  mus- 
cles of  the  tympanum  with  their  power  of  motion. 

The  tympanic  plexus  seems  to  be  the  great  source  from 
whence  all  parts  of  the  tympanum  are  supplied,  as  it  is 
formed  of  branches  from  the  chorda  tympani,  portio  dura, 
glosso  pharyngeal,  par  vagum,  and  sympathetic;  supply- 
ing the  membrana  tympani,  and  lining  membrane  of  the 
cavity,  the  fenestra  ovalis,  the  Eustachian  tube,  the  muscles, 
&c.,  and  establishing  relations  with  the  soft  palate,  tongue, 
pharynx,  eye,  nose,  and  system  generally. 

Blood-vessels  of  the  Ear. — The  arteries  of  the  labyrinth 
come  from  the  internal  auditory,  which  is  a  branch  either  of 
the  superior  cerebellar  or  the  basilar.  This  enters  the  mea- 
tus  along  with  the  auditory  nerve,  pursues  a  similar  course 
and  divides  into  minute  branches,  supplying  the  vestibule, 
cochlea,  and  semi-circular  canals. 


THE  TONGUE  OR  ORGAN  OP  TASTE.          377 

The  external  ear,  composed  of  the  auricle  and  rneatus, 
is  supplied  by  the  anterior  auricular,  branches  of  the  tem- 
poral, and  the  posterior  auricular,  and  occipital  from  the 
external  carotid. 

The  middle  ear  is  supplied  from  the  tympanic  branch  of 
the  internal  maxillary,  which  enters  at  the  fissure  of  Glas- 
serus,  and  with  a  branch  from  the  stylo-mas toid,  forms  a 
"  coronet"  round  the  membrana  tympani,  from  which 
radiate  numerous  branches  upon  its  surface.  The  internal 
carotid,  as  it  passes  through  the  canal,  also  sends  a  branch 
to  the  tympanum. 

General  Remarks. — In  looking  at  the  different  parts  com- 
posing the  ear  collectively,  and  their  several  relationships 
with  one  another,  it  seems  manifest  that  the  external  ear, 
like  a  trumpet,  is  designed  to  collect  and  concentrate  the 
sounds  which  fall  upon  it,  that  the  meatus  externus  conducts 
and  reflects  from  every  part  of  its  surface  the  sonorous 
undulations  to  the  membrana  tympani,  that  this  membrane 
is  then  thrown  into  vibrations,  and  forming  the  outer  wall 
of  the  middle  ear,  transmits  its  vibrations  to  the  little  chain 
of  bones  within  the  tympanum,  with  which  it  is  connected, 
that  these  in  their  turn,  being  attached  to  the  membrane  of 
the  vestibule  by  means  of  the  stapes,  throw  it  also  into 
similar  vibrations,  which  are  now  communicated  to  the 
fluid  and  nerves  of  the  labyrinth,  whence  the  impressions 
are  finally  conveyed  to  the  sensor ium.  The  air  in  the  tym- 
panum, by  means  of  the  Eustachian  tube,  it  should  have 
been  stated,  is  a  very  essential  aid  in  favoring  the  vibra- 
tions, and  in  conducting  them  in  their  progress  to  the 
auditory  nerve. 

SECTION  III. 

THE  TONGUE  OR   ORGAN  OF  TASTE. 

Taste  is  the  faculty  which  the  tongue  possesses,  in  the 
discrimination  of  sapid  bodies.  This  power  also  resides  in 
the  palate  and  lining  membrane  of  the  mouth,  though  not 
to  the  same  extent  as  in  the  tongue. 

1 


378          THE  TONGUE  OK  ORGAN  OF  TASTE. 

The  anatomy  of  the  tongue  (Figs.  86,  87,  88,  90,  91,) 
has  been  given  under  the  head  of  "  organs  of  deglutition/' 
It  was  there  stated  to  he  very  complex  in  its  structure,  and 
to  perform  a  variety  of  functions ;  composed  of  no  less  than 
ten  muscles,  by  which  it  can  be  moved  in  every  possible 
direction.  It  is  most  efficient  in  the  first  stages  of  digestion, 
and  is  moreover,  in  man,  the  great  instrument  of  speech.  It 
has  no  less  than  six  large  nerves,  by  which  it  is  endowed  both 
with  general  and  special  sensation,  i.  e.  the  general  sense  of 
feeling  and  the  special  sense  of  taste.  Grlands  likewise  enter 
into  its  composition,  an  immense  number  of  blood-vessels 
ramify  throughout  its  substance,  and  the  whole  is  covered 
by  mucous  membrane;  so  that  the  tongue  is  one  of  the  most 
complex  and  highly  organized  portions  of  the  body. 

The  papillary  membrane  of  the  tongue  is  regarded  as  the 
especial  seat  of  taste,  and  is  the  only  portion  of  its  struc- 
ture requiring  any  remarks  in  this  place,  in  addition  to 
what  has  already  been  given.  This  papillary  or  gustatory 
membrane  has  the  closest  analogy  with  the  skin,  and  is 
considered  as  possessing  essentially  the  same  elements.  Its 
cliorion  or  cutis-vera  is  as  dense  as  any  part  of  the  skin,  and 
has  a  large  number  of  muscular  fibres  inserted  into  it,  by 
means  of  which  its  papillae  can  be  brought  readily  into 
contact  with  every  portion  of  food ;  and  thus  this  muscular 
appendage  to  the  papillary  membrane  is  regarded  as  play- 
ing an  essential  part  in  the  function  of  taste.  Its  papillae 
are  like  those  of  the  skin,  but  larger  and  much  more  de- 
veloped. Its  rete  mucosum  has  the  same  indistinctness, 
Its  epithelium  is  distinctly  shown,  and  has  received  the 
name  ofperiglottis,  having  in  some  animals  the  consistence 
of  horn. 

The  epithelium  of  the  tongue  can  be  removed  by  macera- 
tion and  by  certain  inflammatory  diseases,  and  is  found  to 
have  an  arrangement  precisely  like  the  epidermis  of  the 
skin,  and  to  form  a  sheath  of  protection  to  the  several  pa- 
pillae upon  its  surface.  These  papillae  are  very  numerous, 
and  were  stated  to  have  various  names  according  to  their 
size  and  shape,  as  the  po.pillce  maximce,  medice,  fungiformes} 


THE  NOSE  OR  ORGAN  OF  SMELL.  379 

Jiliformes,  &c.  The  minute  structure  of  the  papillae  is  be- 
lieved to  consist  essentially  of  capillaries  and  nerves.  The 
capillaries  are  seen  disposed  in  the  form  of  arches  and  loops, 
while  the  precise  arrangement  of  the  nervous  tissue,  which 
is  very  soft,  is  not  ascertained. 

The  anterior,  lateral,  and  posterior  parts  of  the  clorsum  of 
the  tongue  possess  the  faculty  of  taste  in  the  highest  de- 
gree ;  the  anterior  and  lateral  papillae  being  thought  the 
most  quickly  sensitive  to  the  qualities  of  sapid  bodies,  while 
the  posterior  retain  their  impressions  for  a  longer  time. 

The  papillae  and  tongue  are  most  abundantly  supplied 
with  nerves  which  come  from  three  sources  ;  the  ninth  or 
hypoglossol,  the  gloss o-pharyngeal,  and  the  lingual  or  gusta- 
tory branch  of  the  fifth.  The  question  now  is,  which  of 
these  nerves  is  the  nerve  of  taste  ?  The  ninth  nerve,  it  is 
pretty  well  agreed,  is  one  of  motion,  and  supplies  the  differ- 
ent muscles  of  the  tongue.  The  glosso-pharyngeal  is  found 
to  be  exclusively  distributed  to  the  mucous  membrane,  and 
its  papillae  covering  the  base  of  the  tongue;  while  the  gus- 
tatory goes  to  the  papillaa  on  the  tip  and  sides  of  the 
tongue.  Hence  these  two  latter  nerves  are  regarded  as  the 
source  of  common  sensation  and  the  special  sense  of  taste. 
The  glosso-pharyngeal  is  also  regarded  as  the  medium  of 
sympathy  between  the  tongue  and  stomach,  and  as  com- 
bining in  harmonious  concert  all  the  various  organs  con- 
cerned in  deglutition. 
\ 

SECTION    IV. 

THE  NOSE  OR  ORGAN  OP  SMELL. 

The  nosej  occupying  a  situation  between  the  orbits,  above 
the  mouth  and  in  front  of  the  pharynx,  is  a  symmetrical 
organ  placed  along  the  median  line  of  the  body.  It  con- 
sists of  a  variety  of  parts  adapted  to  the  purposes  of  smell, 
and  is  likewise  an  open  avenue  for  the  free  passage  of  the 
air  during  respiration. 

Its  anatomical  elements  include  bone,  muscle,  cartilages, 
blood-vessels,  and  nerves,  covered  by  the  common  integu- 


380  THE  NOSE  OR  ORGAN  OF  SMELL. 

ment.  The  bones  are  the  ossa-nasi,  and  nasal  processes  of 
the  superior  maxillary  bones,  which  have  been  already  de- 
scribed among  the 
passive  organs  of  the 
head.  The  muscles 
are  the  pyramidalis 
nasij  compressor  nasi, 
levator  labii  superior- 
is  alceque  nasi,  and 
depressor  labii  supe- 
rioris  alceque  nasi. 
These  also  have  been 
described  under  the 
head  of  organs  of  expression  and  prehension. 

The  cartilages  constitute  an  important  division  of  the  ex- 
ternal portion  of  the  nose,  and  are  five  in  number,  one  central, 
two  lateral,  and  two  alar.  The  central,  median  or  septal  car- 
tilage, separates  the  nostrils,  is  of  a  triangular  form,  and  is 
connected  above  with  the  nasal  bones  and  lateral  cartila- 
ges, below  with  the  palate  processes  of  the  superior  maxil- 
lary bones,  and  posteriorly  with  the  vomer  and  gethmoid 
septum.  It  is  flexible,  elastic,  and  has  considerable  strength. 
Its  anterior  border  is  thick  and  rounded,  and  though 
generally  vertical,  it  occasionally  projects  to  the  one  side, 
being  concave  on  the  opposite. 

The  lateral,  or  fibro-cartilages,  are  connected  superiorly 
and  externally  with  the  inferior  edge  of  the  nasal  bones, 
and  anterior  margin  of  the  nasal  process  of  the  superior 
maxillary ;  in  front  with  the  nasal  septum,  and  below  with 
the  alar  cartilages. 

The  alar  cartilages  occupy  the  anterior  part  of  the  nasal 
openings,  and  are  so  curved  as  to  form  the  rim,  or  boun- 

FIG.  110  represents  the  first  pair  or  olfactory  nerves,  a  Frontal  sinus. 
6  Sphenoidal  sinus,  c  Hard  palate,  d  Olfactory  bulb,  e  Branches  of  olfac- 
tory on  the  superior  and  middle  turbinated  bones.  /  Spheno  palatine  nerves 
from  the  second  division  of  the  fifth,  g  Internal  nasal  nerve  from  the  first  di- 
vision of  the  fifth,  h  Branches  of  g  to  the  Schneiderian  membrane,  i  Ganglion 
of  Cloquet.  j  Anastomosis  of  branches  of  the  fifth  or  lower  turbinated  bone. 


THE  NOSE  OK  ORGAN  OP  SMELL.  381 

dary.  At  the  point  of  the  nose,  these  cartilages  are  thick 
and  constitute  the  tip,  or  lobe ;  each  passes  round  the  ori- 
fice of  the  nostril,  in  a  semicircular  form,  having  its  in- 
ternal surface  deeply  concave,  hy  which  the  nostrils  are 
enlarged.  As  they  make  their  curve,  they  become  widened 
at  their  posterior  part,  by  having,  as  appendages,  three  or 
four  small  cartilaginous  plates  connected  by  fibrous  tissue. 
The  two  alar  cartilages  meet,  in  front,  beneath  the  septum, 
and  are  attached,  by  fibro-cellular  tissue,  to  the  nasal  spine 
of  the  superior  maxillary  bones,  forming  a  projection  called 
the  columna.  All  these  cartilages  are  connected,  by  fibrous 
tissue,  to  one  another  and  to  the  bones,  and  are  readily 
movable,  by  the  muscles  attached  to  them,  so  as  to  enlarge 
or  contract  the  anterior  nares  at  pleasure. 

Each  nostril  has  its  entrance  protected  by  some  stiff 
hairs,  called  vibrissce,  which  prevent  the  introduction  of 
foreign  bodies,  along  with  the  air,  in  breathing. 

The  integument  of  the  nose  is  thick  and  dense,  and  so 
closely  attached  to  the  cartilages,  as  with  difficulty  to  be 
separated  from  them.  It  is  supplied  with  numerous  seba- 
ceous follicles,  whose  ducts  open  upon  the  surface  and  fre- 
quently present  the  appearance  of  numerous  black  dots, 
from  the  presence  of  carbon.  This  sebaceous  secretion  be- 
comes solidified,  and,  by  pressing  the  follicles,  can  be  forced 
out  in  fine,  long  threads,  which  have  been  compared  to 
"small,  white  maggots  with  black  heads."  These  follicles 
are  liable  to  hypertrophy,  and  occasionally  become  so  large 
as  to  present  a  very  tuberculated  and  unsightly  appear- 
ance. 

The  use  of  this  secretion,  which  is  of  an  oily  nature,  is 
to  preserve  the  skin  of  the  nose  in  a  soft  and  pliable  con- 
dition, as  well  as  to  guard  against  excessive  changes  in 
temperature. 

Nasal  Fossa,  (Fig.  111.) — The  nasal  fossce  constitute  the 
internal  or  posterior  part  of  the  nose,  forming  its  second  di- 
vision. They  consist  of  two  very  irregular  cavities  extend- 
ing back  to  the  pharynx,  and  bounded  above  by  the  nasal 
cartilages,  nasal,  frontal,  cetTimoidal,  and  sphenoidal  bones, 


THE  NOSE  OR   ORGAN   OF  SMELL. 

forming  the  roof  of  the  nostrils;  below  by  the  palatine 
processes  of  the  superior  maxillary  and  palate  bones,  with  a 
FIG.  in.  portion  of  the  velum  palati, 

constituting  the  floor  of 
these  fossee,  as  well  as  of 
the  nostrils;  externally  they 
are  bounded  by  the  superior 
maxillary,  lachrymal,  ceth- 
moid,  turbinated,  and  palate 
bones,  and  the  internal  pter- 
ygoid  plate  of  the  sphenoid; 
internally  they  are  separa- 
ted, on  the  median  line,  by 
the  septum  composed  of  the  vomer,  the  nasal  lamella  of  the 
(Ethmoid,  and  the  nasal  cartilaginous  septum.  ' 

The  outer  wall  is  very  irregular,  being  roughened  by  the 
three  turbinated,  or  spongy  bones — the  superior,  middle, 
and  inferior.  These  have  spaces  between  them,  known  as 
meatuses.  As  the  space  between  the  superior  and  middle 
spongy  bones  is  the  superior  meatus ;  that  between  the 
middle  and  lower  is  the  middle  meatus  ;  and  that  between 
the  lower  and  floor  of  the  nostrils  is  the  inferior  meatus. 
Into  the  superior  meatus  the  posterior  wthmoid  cells  and 
sphenoid  sinuses  open. 

The  middle  meatus  is  the  widest,  and  opens  into  the 
antrum.  In  the  dry  bone  this  opening  appears  large; 
while  in  the  fresh  state  it  will  only  admit  a  small  probe, 
being  closed  by  a  fold  of  the  mucous  membrane.  It  receives 
the  anterior  cethmoid  cells,  and  has  in  its  front  part  a  groove 
called  the  infundibulum,  which  leads  to  the  frontal  sinus. 

FIG.  Ill  represents  a  vertical  section  of  the  Nasal  Fossae.  1  Anterior 
fossae  of  the  cranium.  2  Dura  mater,  covering  the  fossae.  3  Dura  mater 
raised.  4  Cristagalli  of  aethmoid  bone.  5  5  Cribriform  plate.  6  Nasal  lamel- 
la. 7  7  Middle  turbinated  bones.  8  8  Ethmoid  cells.  9  9  Os-planum.  10  10 
Inferior  turbinated,  or  spongy  bones.  11  Vomer.  12  Superior  maxillary  bone. 
13  Articulation  of  superior  maxillary  with  the  eethmoid.  14  Front  wall  of 
the  antrum.  15  Fibrous  membrane  of  the  antrum.  16  Mucous  membrane  of 
antrum.  17  Palatine  process  of  superior  maxillary  bone.  18  Roof  of  the  mouth. 
19  A  section  of  the  mucous  membrane. 


THE  NOSE  OR  ORGAN  OF  SMELL.  383 

The  inferior  meatus  lias  the  nasal  duct  opening  into  its 
anterior  portion — while  the  Eustachian  tube  is  seen  behind 
on  a  level  with  the  inferior  spongy  bone. 

These  different  meatuses  constitute  so  many  channels, 
extending  from  before  backward,  in  the  nasal  fossce,  which 
with  the  spongy  bones,  present  a  large  amount  of  surface 
covered  by  mucous  membrane,  upon  which  the  air  in  pass- 
ing along,  makes  odorous  impressions. 

The  mucous  membrane  lining  the  nasal-fossae  is  called 
the  pituitary  or  Sclmeiderian  membrane.  It  is  attached  to 
the  internal  surface  of  the  bones  of  the  nose,  lines  the  si- 
nuses, is  traced  into  the  wthmoid  and  sphenoid  cells,  passes 
through  the  nasal  duct}  and  is  continuous  with  the  tunica 
conjunctiva  of  the  eye.  Backward  through  the  posterior 
nares,  it  becomes  continuous  with  the  mucous  membrane  of 
the  mouth  and  pharynx,  and  consequently  with  the  great 
gastro-pulmonary  division.  In  some  parts  it  is  very  vascu- 
lar, soft,  and  thick,  as  on  the  turbinated  bones  and  septum. 
In  other  places  it  adheres  strongly  to  the  periosteum.  It  is 
pale  and  thin  in  the  sinuses.  It  is  constantly  moistened 
with  mucus,  and,  like  mucous  membranes  elsewhere,  has 
its  surface  covered  with  an  epithelium.  This  epithelium  is 
of  the  columnar  form,  except  in  the  sinuses  where  it  is 
found  to  have  more  of  the  squamous  character.  It  is  every 
where  observed  to  bo  furnished  with  cilia,  whose  vibratile 
motions,  it  is  believed,  have  an  important  influence  in 
directing  the  mucus  towards  the  various  openings  by 
which  it  is  discharged. 

Blood-vessels  of  the  Nose. — The  terminating  branches  of 
the  facial  artery  supply  the  external  nose,  while  the  'an- 
terior and  posterior  wthmoidal  of  the  ophthalmic,  with  the 
splieno-palatine  and  pterygo-palatine  of  the  internal  maxil- 
lary, supply  the  nasal  fossse  or  internal  nose. 

Nerves. — The  olfactory  or  first  pair,  (Fig.  110,)  are  the 
special  nerves  of  the  nose  and  of  the  sense  of  smell ;  their 
development  being  always  found  in  the  lower  animals  in 
proportion  to  the  acuteness  and  development  of  this  sense. 

They  come  from  the  brain  through  the  foramina  in  the 

'.  -....•* 

X 
j 


334  THE  SKIN   OR   ORGAN   OF  TOUCH. 

cribriform  plate  of  the  sethmoid  bone,  enveloped  by  fibrous 
sheaths,  and  are  distributed  mostly  upon  the  superior  part 
of  the  pituitary  membrane,  forming  plexuses  in  its  sub- 
stance. The  branches  of  the  olfactory  are  seldom  found  to 
pass  lower  than  the  middle  spongy  bone  and  the  middle 
part  of  the  septum.  "Thus,"  as  Cruveilhier  remarks,  "while 
the  upper  and  extremely  narrow  part  of  each  nasal  fossa 
is  the  essential  seat  of  the  sense  of  smell,  the  lower  and 
much  wider  part  only  gives  passage  to  the  air  during  the 
act  of  respiration." 

Besides  the  special  sense  of  smell,  there  is  also  the  gen- 
eral sense  of  feeling  derived  from  the  first  and  second  divis- 
ions of  the  fifth  pair,  or  branches  from  the  ophthalmic  and 
superior  maxillary  nerves,  which  are  likewise  distributed  to 
every  part  of  the  nose.  These  branches  from  the  fifth,  differ 
from  the  olfactory  in  not  having  the  plexiform  arrangement. 

SECTION    V. 

THE  SKIN  OR  ORGAN  OF  TOUCH,    (Fig.   19.) 

The  sense  of  touch  is  coextensive  with  the  whole  external 
cutaneous  surface,  and  those  portions  of  the  internal  cutane- 
ous or  mucous,  which  are  adjacent  to  the  skin  and  continu- 
ous with  it.  The  diffusive  character  of  the  sense  of  touch, 
and  the  extent  of  the  apparatus  composing  it,  distinguish 
it  from  the  rest  of  the  senses,  whose  limits  are  circum- 
scribed and  confined  solely  to  the  head  and  face.  Though 
it  be  true  that  the  sense  of  touch  resides  generally  in  the 
skin,  yet  it  is  also  true  that  there  are  some  portions  in 
which  it  is  much  more  highly  developed,  ^,nd  where  the 
sense  of  touch  is  said  most  especially  to  reside — that  is  in 
the  skin  covering  the  extremities  of  the  fingers  and  toes — 
and  here  it  is  discriminated  by  the  name  of  tact. 

The  sense  of  touch  enables  every  one  to  recognise  the 
pressure  and  presence  of  external  bodies,  when  they  come 
in  contact  with  his  skin,  also  to  determine  many  of  their 
physical  properties,  as  form,  size,  weight,  consistence  and 
temperature.  But  for  the  discernment  of  other  qualities  of 


THE  SKIN   OR   ORGAN  OF  TOUCH.  385 

a  more  refined  character,  a  proportionate  refinement  of 
organization  seems  necessary,  and  this  is  found  in  the  tips 
of  the  fingers. 

The  skin  is  also  an  organ  of  secretion  and  absorption. 
The  secretion  is  of  two  kinds,  of  which  one  is  a  separa- 
tion from  the  blood  of  a  very  fine  halitus,  the  insensible 
perspiration,  or  exhalation.  When  this  exhalation  is  in 
excess  and  forms  drops,  it  constitutes  the  sweat.  This  is  a 
very  important  function,  as  it  relieves  the  blood  of  a  large 
amount  of  water,  saline  matters,  carbonic  acid  and  other 
substances,  which,  if  retained,  would  be  injurious  to  the 
system.  The  perspiration  by  evaporation  acts  as  a  cooling 
process,  and  is  thus  highly  useful  in  carrying  off  the  excess- 
ive heat  of  the  body.  The  other  secretion  of  the  skin  is  of 
an  oily  nature,  which  keeps  it  in  a  soft  and  pliant  condition, 
protects  it  from  the  drying  agency  of  the  air,  and  shields  it 
from  external  moisture.  It  is  also  an  organ,  as  stated,  of 
absorption. 

The  skin  performing  so  great  a  variety  of  functions,  must 
necessarily  possess  a  very  complex  organization.  Its  anato- 
my has  been  given  already  in  detail,  under  the  head  of  the 
"cutaneous  tissue,"  in  the  first  part  of  this  work.  It  is 
there  stated  to  consist  of  three  membranous  layers  super- 
imposed the  one  upon  the  other,  and  called  the  cuticle, 
rete  mucosum,  and  cutis  vera,  of  numerous  glands  and 
follicles,  with  a  most  minute  and  extensive  capillary  net- 
work of  arteries,  veins,  nerves,  and  lymphatics.  In  addi- 
tion to  these  there  are  also  the  appendages  of  the  hair  and 
the  nails. 

The  only  part  of  the  structure  of  the  skin,  therefore, 
necessary  to  make  any  additional  remarks  upon,  is  the  pa- 
pillary layer  or  that  portion  directly  connected  with  the 
sense  of  touch.  This  layer  abounds  with  numerous  papillse 
spread  every  where  over  its  surface,  but  more  distinct 
and  of  greater  size  in  some  places  than  in  others.  The 
fingers  and  toes,  and  the  palmar  and  plantar  surfaces 
of  the  hands  and  feet  have  them  most  highly  developed. 
The  skin  upon  the  ends  of  the  fingers,  where  the  sense  of 
25 

V 


386  INTERNAL  ORGANS  OF  SENSE. 

touch  most  especially  resides,  presents  ridges  and  grooves 
of  an  arched  or  curved  form ;  each  ridge  is  a  row  of  conical 
papillae,  and  in  the  grooves  the  exhalant  orifices  are  found 
to  open.  The  minute  structure  of  the  papillae  consists  of 
blood  vessels,  nerves,  and  a  spongy  erectile  tissue,  and  is 
believed  to  be  exactly  analogous  with  those  of  the  tongue. 
The  vessels  are  seen  as  convoluted  loops,  but  the  precise 
termination  of  the  nerves,  whether  in  loops,  plexuses,  or 
bulbs,  is  not  yet  settled. 

That  the  papillae,  however,  are  exceedingly  sensitive,  and 
constitute  the  essential  seat  of  touch,  there  is  no  doubt. 

The  mucous  membrane  of  the  eyelids,  nose,  mouth, 
larynx,  trachea  and  lungs,  is  sensible  to  heat  and  cold, 
while  that  of  the  vagina,  rectum,  and  urethra,  is  in  addi- 
tion sensible  also  to  touch. 


CHAPTER  Y. 

INTERNAL    ORGANS   OF   SENSE. 

THE  internal  organs  of  sense  comprise  the  cerebro-spinal 
axis,  by  which  is  understood  the  brain  and  spinal  marrow. 
These  organs  are  the  source  of  sensation  and  motion  to  all 
the  organs  we  have  been  examining,  as  those  belonging  to 
the  mouth  and  face  and  external  parts  of  the  head.  They 
constitute  the  foundation  and  main-spring  of  all  their  ac- 
tions, and  without  them  the  functions  of  these  subordinate 
organs  could  not  be  exercised.  The  examination  of  the 
brain  and  spinal  marrow,  then,  as  the  source  of  power  to  all 
these  parts,  seems  to  follow  very  naturally,  and  comes  next 
in  the  order  of  investigation  we  have  thought  best  to 
pursue. 

This  will  make  complete  the  anatomy  of  the  head,  and 
carry  out  the  design  in  view,  which  is  to  endeavor  to  illus- 
trate as  far  as  possible,  practical  physiology,  by  bringing  or- 
gans together,  however  dissimilar  in  structure,  which  have 
a  relationship  or  community  of  action  in  the  discharge  of 
any  particular  function  or  series  of  functions ;  and  thus 


SPINAL  MARROW.  387 

show,  step  by  step,  the  relative  dependency  of  the  several 
parts,  and  the  inseparable  union  of  the  anatomy  and  phys- 
iology of  the  whole,  in  the  great  business  of  continuing 
and  preserving  life. 

The  brain  and  spinal  marrow  are  not  only  the  sources 
of  power  to  the  different  parts  of  the  head,  but  they  are 
further  the  great  centres  of  action  to  the  whole  nervous 
system  and  all  its  dependencies. 

We  shall  consider  the  cerebro-spinal  axis  in  the  natural 
order  of  its  development,  beginning  with  the  spinal  marrow. 

SECTION  I.  \ 

SPINAL  MARROW.    (Fig.   14.) 

The  situation  of  this  organ  within  the  spinal  canal, 
together  with  its  divisions,  structure,  and  functions,  has 
already  been  partly  considered  under  the  head  of  nervous 
tissue.  A  few  more  additional  remarks  will  be  all  that  is 
necessary  in  this  place. 

The  spinal  marrow,  (medulla  spinalis,)  in  common  with 
the  brain,  has  three  membranes  surrounding  it,  the  dura 
mater,  tunica  arachnoidea,  and  pia  mater — the  whole  en- 
closed in  a  strong  bony  case,  called  the  vertebral  or  spinal 
canal. 

Dissection. — After  removing  the  soft  parts  covering  the 
spine,  divide,  with  the  saw,  the  crura  of  the  spinous  pro- 
cesses, close  to  the  roots  of  the  transverse,  the  whole  length 
of  the  canal;  then  raise  this  portion  with  an  elevator, 
when  will  be  first  seen  a  considerable  amount  of  soft,  red- 
dish cellular  and  adipose  tissue,  between  the  bones  and 
the  membranes  of  the  spinal  cord,  which  at  this  point  have 
a  very  loose  connection — while  in  front  the  dura  mater  is 
closely  attached  to  the  bodies  of  the  spine,  by  means  of  the 
posterior  ligaments.  It  will  also  be  noticed  that  the  spinal 
marrow  does  not  fill,  by  a  considerable  space,  the  whole 
diameter  of  the  bony  canal. 

The  Dura  Mater  ^  (mater,  mother,)  so  called  from  being 
formerly  supposed,  by  the  older  anatomists,  to  be,  along 


388  DURA   MATER. 

with  the  pia  mater,  the  mother  membranes,  which  give 
origin  to  all  the  rest  of  the  "body,  is  the  outer  one,  cover- 
ing the  spinal  cord,  and  continued  upon  the  brain.  It 
is  called  tlieca  vertebralis,  and  extends  from  the  foramen 
magnum,  to  which  it  adheres,  down  the  spinal  canal  its 
whole  length,  to  the  sacrum,  where  it  sends  off  several 
processes  forming  sheaths  for  the  sacral  nerves.  It  differs 
from  the  cranial  portion,  at  the  posterior  part  of  the  canal, 
in  not  being  connected  with  the  bones;  but  having,  inter- 
posed between  it  and  the  bony  arches,  a  soft  fatty  tissue, 
which  has  been  compared  to  the  marrow  of  the  long  bones. 
The  external  surface,  at  this  point,  is  smooth  and  covered 
by  a  plexus  of  veins.  In  front,  as  just  stated,  it  is  attached 
to  the  posterior  vertebral  ligaments.  On  each  side  it  sends 
off  a  tubular  process  or  sheath,  for  each  of  the  spinal  nerves, 
which  extends  beyond  the  intervertebral  foramina,  and 
becomes  lost  on  the  cellular  tissue. 

It  has  a  much  greater  capacity  than  the  cord  it  encloses, 
is  larger  in  its  upper  and  lower  portions,  and  contracted 
in  the  middle.  Its  inner  surface  is  smooth,  and  presents 
double  rows  of  openings  through  which  pass  the  anterior 
and  posterior  roots  of  the  spinal  nerves;  here  also  is  seen 
the  attachment  of  the  ligamenta  denticulata,  or  tooth-like 
processes,  disposed  laterally. 

Structure. — Its  structure  is  essentially  fibrous,  having 
the  fibres,  which  are  white,  running  in  various  directions, 
and  in  some  places,  as  in  the  brain,  separable  into  two 
laminas.  It  is  a  strong,  resisting,  inelastic  tissue,  resem- 
bling the  sclerotic  coat  of  the  eye,  and,  like  it,  admirably 
adapted  for  protecting  the  spinal  marrow  and  the  brain. 

The  blood-vessels  of  the  spinal  portion  of  the  dura  mater 
are  the  arteries  which  come  from  the  vertebral,  intercostal, 
lumbar,  and  sacral.  The  veins  accompanying  the  arteries 
are  found  to  terminate  in  the  two  long  vertebral  sinuses, 
which  extend  the  whole  length  of  the  spine  on  the  back 
part  of  the  bodies  of  the  vertebrae. 

Tunica  arachnoidea  (am^,  a  spider's  web,  £t-5of,  likeness) 
is  the  next  membrane,  after  removing  the  dura  mater,  and 


PIA  MATER.  389 

takes  its  name  from  its  extreme  tenuity  and  transparency. 
It  lines  the  dura  mater,  and  is  reflected  from  it  upon  the 
nerves  to  the  spinal  cord,  which  it  loosely  covers.  Hence 
this  membrane  is  much  larger  than  the  spinal  cord,  and 
allows  of  a  considerable  space  between  the  two,  called  the 
sub-araclmoid  space.  This  space  is  occupied  by  a  serous 
fluid,  which  dilates  the  arachnoid,  and  is  said  completely  to 
fill  the  cavity  of  the  theca-vertebralis.  This  fluid  is  of  use 
in  keeping  up  a  gentle  pressure  and  giving  support  to  the 
cord,  and  in  filling  up  all  the  inequalities  on  its  surface; 
allowing  the  greatest  freedom  in  all  its  movements,  and 
guarding  it  against  concussions.  The  portion  of  the  arach- 
noid covering  the  dura  mater  is  called  parietal,  that  upon 
the  cord  is  the  visceral,  and  the  space  between  the  two  con- 
stitutes the  arachnoid  cavity,  not  found  to  contain  much 
fluid.  It  forms  a  sheath  for  the  nerves  and  is  reflected  back 
upon  the  theca,  forming  at  each  nerve  a  small  cul  de  sac. 
Between  the  anterior  and  posterior  roots  of  the  nerves 
little  reflections  or  tooth-like  processes  of  this  membrane, 
about  twenty-two  in  number,  are  seen  to  extend  from  the 
pia  mater,  laterally  along  the  spinal  cord,  and  in  a  regular 
series,  to  be  connected  by  their  little  points,  to  the  inner 
surface  of  the  dura  mater.  These  processes  are  called  the 
ligamenta  denticulata;  each  encloses  a  fibrous  band  or  thread, 
and  the  whole  are  designed  to  separate  the  anterior  and 
posterior  roots  of  the  nerves,  and  to  give  support  to  the 
cord  in  the  lateral  direction. 

The  structure  of  the  arachnoid  is  serous,  and  presents 
the  usual  smooth,  glistening,  delicate  and  transparent  ap- 
pearance of  serous  membranes  every  where. 

The  Pia  Mater  forms  the  third  and  innermost  covering 
of  the  cord.  It  is  considered  the  same  and  continuous  with 
that  of  the  brain.  But  there  is  this  important  difference, 
that  while  the  pia  mater  of  the  brain  is  essentially  vascu- 
lar, the  pia  mater  of  the  spinal  marrow  is  essentially 
fibrous,  that  of  the  brain  being  loaded  with  vessels,  while 
that  of  the  cord  has  very  few.  It  is  dense  and  strong,  and 
compresses  the  cord  to  such  a  degree  that,  when  opened,  the 

X 


390  PI  A  MATER. 

nervous  matter  of  the  cord  protrudes.  Its  external  surface 
is  rather  rough  from  the  cellular  and  fibrous  filaments  con- 
necting it  with  the  arachnoid.  On  this  surface  are  also  seen 
large  and  tortuous  vessels."  Its  internal  surface  is  connected 
by  delicate  vessels  and  cellular  threads  to  the  cord.  The 
pia  mater,  besides  surrounding  the  spinal  marrow,  sends 
a  duplication  into  both  its  anterior  and  posterior  median 
fissure,  and  also  gives  a  neurilemma  to  each  nerve. 

The  function  of  this  membrane  is  rather  one  of  protection 
to  the  spinal  cord,  than  that  of  a  vascular  membrane  as 
upon  the  brain. 

The  Spinal  Marrow,  (Fig.  14,)  it  has  been  stated  under 
the  head  of  the  nervous  tissue,  consists  of  two  kinds  of 
nervous  matter,  the  white  and  the  gray,  not  disposed  as 
they  are  in  the  brain.  The  white  or  medullary  forms 
the  whole  exterior  covering,  while  the  gray  or  cineritious 
occupies  the  interior. 

Besides  its  division  into  two  lateral  and  symmetrical 
parts  by  the  anterior  and  posterior  median  fissures,  and 
the  lateral  subdivision  of  these,  by  two  other  fissures, 
so  that  each  half  of  the  cord  consists  of  three  columns 
or  rods,  according  to  Sir  Charles  Bell,  the  anterior  and 
posterior  columns,  and  the  middle  or  respiratory  tract; 
two  others  have  been  added  by  some,  making  the  cord 
consist  of  eight  divisions,  four  on  each  side  of  the  median 
fissure,  in  the  following  manner :  first,  the  anterior,  between 
the  median  fissure  and  anterior  nerves;  second,  the  lateral 
between  the  roots  of  the  nerves;  third,  the  posterior  between 
the  posterior  fissure  and  posterior  nerves;  and  fourth,  the 
posterior  pyramids,  situated  only  at  the  upper  part  of  the 
cord,  and  close  to  the  posterior  fissure. 

Another  division  of  the  spinal  marrow,  and  one  thought 
most  natural,  is  the  blending  together  of  the  anterior  and 
middle  columns,  under  the  head  of  antero  lateral,  and  count- 
ing the  posterior  column  as  one,  making  but  four  in  all. 
The  bottoms  of  the  anterior  and  posterior  fissures,  have 
transverse  bands  or  commissures,  extending  from  side  to 
side,,  and  connecting  the  lateral  halves  of  the  spinal  cord. 


SPINAL  NERVES.  391 

According  to  the  experiments  of  Sir  Charles  Bell,  Ma- 
gendie,  and  others,  it  has  also  been  stated  that  the  anterior 
columns  of  the  spinal  marrow  are  the  sources  of  motion, 
and  the  posterior  those  of  sensation. 

It  is  also  found  that  the  medullary  matter  of  the  cord 
has  longitudinal  fibres  extending  to  the  brain,  and  that 
these  medullary  fibres  are  the  media  of  communication 
between  the  brain  and  spinal  marrow,  being  the  conductors 
of  all  impressions  to  the  brain,  constituting  conscious  per- 
ception, and  transmitters  of  all  volitions  from  the  brain, 
giving  rise  to  voluntary  muscular  motions.  But  the  spi- 
nal marrow  has  nervous  fibres  which  stop  within  the 
cord  itself,  and  do  not  go  to  the  brain,  and  even  without 
the  brain  are  conductors,  both  of  sensation  and  motion — 
but  of  a  sensation  which  is  not  conscious,  and  a  motion 
which  is  involuntary — powers  which  Mr.  Marshall  Hall 
has  shown  to  be  derived  from  the  spinal  marrow  itself, 
acting  as  an  independent  ganglionic  centre.  The  nerves 
which  arise  from,  and  terminate  in  it,  he  calls,  as  else- 
where mentioned,  the  excito  motory. 

ORIGIN  OF  THE  SPINAL  NERVES. 

All  the  spinal  nerves  are  compound,  and  arise  by  double 
roots — one  anterior,  the  other  posterior;  the  former  arising 
from  the  anterior  columns  and  being  nerves  of  motion  ;  the 
latter  from  the  posterior  columns,  and  designed  for  sensa- 
tion. Each  root  consists  of  several  filaments.  The  anterior 
roots  are  smaller  than  the  posterior,  except  the  first,  or 
sub-occipital,  and  are  separated  from  each  other  by  the 
ligamentum  denticulatum.  These  roots  approach  each 
other,  and  perforate  the  dura  mater  separately,  each  receiv- 
ing a  sheath  from  it.  On  the  posterior  root  a  small  oval 
ganglion  is  seen;  and  immediately  beyond  the  ganglion, 
the  two  roots  come  together  and  constitute  a  proper  spinal 
nerve.  The  number  of  spinal  nerves  is  thirty-one,  eight 
cervical,  twelve  dorsal,  five  lumbar,  and  six  sacral;  though 
some  anatomists  make  but  thirty,  and  others  thirty-two. 

The  ganglia  are  reddish,  firm  bodies,  situated  in  the 


392  THE  BRAIN. 

intervertebral  foramina,  except  those  of  the  sacral  and 
coccygeal  nerves,  which  are  found  in  the  spinal  canal. 
Each  of  the  spinal  nerves,  after  leaving  the  intervertebral 
foramen,  divides  into  anterior  and  posterior  branches.  The 
anterior,  with  the  exception  of  the  first  two  cervical,  are 
much  larger  than  the  posterior,  and  unite  to  form  the  sev- 
eral plexuses,  constituting  the  cervical,  brachial,  lumbar, 
and  sacral,  which  supply  the  muscles  anterior  to  the  spinal 
column,  and  the  upper  and  lower  extremity.  The  posterior 
supply  the  parts  on  the  back  of  the  spinal  column. 

BLOOD-VESSELS  OF  THE  SPINAL   MARROW.    (Fig.   8.) 

The  spinal  cord  is  supplied  with  arteries  from  the  verte- 
bral, intercostal,  lumbar,  and  sacral. 

I'he  vertebral,  at  the  foramen  magnum,  sends  off  the 
anterior  and  posterior  spinal  arteries,  which  descend  the 
whole  length  of  the  cord,  in  front  and  behind.  Branches 
of  the  intercostal,  lumbar  and  sacral,  enter  through  the 
intervertebral  foramina,  to  supply  the  cord. 

The  veins  are  numerous.  One  on  each  side  of  the  mid- 
dle line,  from  its  size,  is  called  the  sinus  columnce  ver- 
tebralisy  and  is  found  on  the  posterior  surface  of  the  bodies 
of  the  vertebrae,  between  them  and  the  dura  mater. 
Branches  running  transversely  join  these  sinuses ;  and 
there  is  also  an  anastomosis  with  the  veins  on  the  outside 
of  the  spinal  canal. 

SECTION  n , 

THE  BRAIN.    (Fig.   16.) 

The  brain  is  regarded  as  the  great  central  portion  of  the 
nervous  system,  and  being  situated  within  the  cavity  of  the 
cranium,  is  called  the  Encephalon,  (wzsqahe,  within  the  head.) 

The  brain  has  four  principal  divisions,  which  we  shall 
examine  in  the  natural  order  of  their  development,  or  from 
below  upward: 

1.  Medulla  oblongata.  3.  Cerebellum. 

2.  Pons  Yarolii.  4.  Cerebrum. 


DURA  MATER  OP  THE  BRAIN.  393 

These  several  divisions  are  all  covered  by  membranes 
which  are  common  to  the  whole,  and  are  the  same  as  those 
of  the  spinal  marrow,  the  dura  mater,  the  tunica  aracli- 
noidea,  and  the  pia  mater.  It  is  only  necessary  for  us 
to  point  out  the  peculiarities  of  these  membranes  as  per- 
taining to  the  brain. 

Dissection. — Make  an  incision  through  the  scalp,  from 
the  ear  upon  the  one  side,  across  the  vertex  to  the  opposite 
ear ;  turn  the  skin  over  the  face  in  front,  and  upon  the 
neck  behind ;  now  with  the  saw  carry  a  circular  incision 
through  the  first  table  of  bone,  commencing  about  an  inch 
above  the  superciliary  arches,  and  terminating  a  little  be- 
low the  external  occipital  protuberance.  A  few  blows  with 
mallet  and  chisel  will  separate  the  internal  table,  and  the 
calvarium  can  be  readily  removed.  The  brain  should  now 
be  removed  from  the  cavity  of  the  cranium,  which  can  be 
done  by  commencing  at  the  anterior  part,  and  gently  rais- 
ing it  from  the  base  of  the  skull,  dividing  from  before, 
backward,  each  nerve  and  vessel  in  succession,,  close  to  the 
bone ;  divide  the  tentoriurn,  and  cut  the  spinal  marrow  as 
low  in  the  neck  as  can  be  reached,  when  the  brain  can  be 
removed. 

Dura  Mater. — The  dura  mater  of  the  brain  is  continuous 
with  that  of  the  spinal  marrow,  is  of  great  strength,  and 
performs  no  less  than  five  different  offices :  first,  it  acts  as 
a  periosteum  to  the  inner  surface  of  the  cranium ;  second, 
it  gives  a  secure  covering  to  the  brain,  especially  needed 
in  early  life  when  the  bones  are  separated ;  third,  it  sends 
in  processes  which  divide  and  support  the  different  parts 
of  the  brain ;  fourth,  it  forms  the  different  sinuses ;  and 
fifth,  it  gives  sheaths  to  the  several  nerves  as  they  leave 
the  cranium.  Its  external  surface  has  a  strong  adhesion  to 
the  internal  surface  of  the  cranium,  so  that  it  presents  a 
rough  appearance  from  the  rupture  of  vessels  and  fibres 
connecting  the  two.  The  adhesion  is  strongest  at  the  base, 
and  along  the  course  of  the  sutures.  It  adheres  to  the 
lesser  wings  of  Ingrassias,  the  petrous  edge  of  the  temporal 
bone,  sends  processes  through  the  several  foramina  of  the 


394  DUKA  MATER  OF  THE  BRAIN. 

cranium,  which  are  continued  into  the  periosteum,  and 
through  the  optic  foramen  around  the  optic  nerve,  into 
the  sclerotica  of  the  eye.  At  some  points  the  attachment 
to  the  hones  is  much  more  feeble  than  at  others,  as  in 
the  occipital  fossse,  and  upon  the  squamous  and  parietal 
bones. 

The  strength  of  this  connection  varies  at  different  peri- 
ods of  life.  In  the  young  it  is  so  strong  as  to  require  the 
scissors,  and  considerable  force,  to  effect  a  separation.  In 
the  adult  the  attachment  is  more  easily  broken ;  while  in 
old  age  it  becomes  so  strong  again  as  to  tear  in  shreds  in 
the  attempt  at  separation. 

When  the  cranium  has  been  successfully  removed,  its 
external  surface,  besides  its  roughness,  also  presents  nu- 
merous red  dots,  which  is  owing  to  the  rupture  of  vessels 
that  form  a  part  of  the  bond  of  union. 

On  the  vertex,  the  dura  mater  has  a  cribriform  appear- 
ance, having  little,  granular,  pale  bodies  projecting  from 
it,  called  glandulce  Pacchioni,  which  we  will  notice  again 
presently.  Kaise  the  dura  mater  by  making  an  incision 
through  it  on  either  side  of  the  middle  line;  its  internal 
surface  is  found  to  be  smooth,  polished,  and  lubricated 
with  serum. 

Its  structure  is  fibro-serous.  The  fibrous  layer,  forming 
a  very  strong  and  firm  capsule  for  the  brain,  consists  of 
two  lamina,  the  outer  acting  as  the  periosteum,  the  inner 
going  to  form  the  different  reflections  of  the  brain.  Its 
serous  layer  is  the  reflected  or  parietal  portion  of  the 
arachnoid,  strongly  adhering  to  the  dura  mater,  and  al- 
ways in  contact  with  the  surface  of  the  brain. 

Blood-vessels,  (Fig.  8.) — The  arteries  supplying  the  dura 
mater  come  from  the  ophthalmic  and  internal  carotid,  which 
send  branches  to  its  anterior  portion.  Its  lateral  parts  are 
supplied  by  the  middle  meningeal  artery,  a  branch  of  the  in- 
ternal maxillary,  its  posterior  portion  by  the  occipital  and 
vertebral,  and  its  basilar  by  the  pharyngeal,  vertebral  and 
internal  carotid.  Its  veins  enter  the  sinuses,  except  those 
of  the  middle  artery,  which  are  vena?  comites. 


REFLECTIONS  OF  THE  DURA  MATER.  395 

The  nerves  are  few  and  small,  and  not  easily  traced. 
Branches,  however,  are  found  going  to  the  dura  mater 
from  the  fifth  pair,  and  hranches  from  the  sympathetic 
accompany  the  meningeal  artery.  In  consequence  there- 
fore of  the  paucity  of  the  nerves,  the  sensibility  of  this 
membrane  is  rather  dull. 

Reflections  of  dura-mater. — The  principal  of  these  reflec- 
tions are  the  falx  cerebri,  tentorium,  and  falx  cerebelli. 
The  falx  cerebri  (falx,  a  sickle)  is  a  process,  of  a  sickle-like 
shape,  from  the  dura  mater  along  its  median  line.  It  is 
situated  between  the  hemispheres  of  the  brain,  which  it 
separates,  and  extends  from  the  foramen  ccecum  and  crista 
galli  of  the  sethmoid  bone,  proceeding  by  its  superior  bor- 
der along  the  middle  line  of  the  frontal  bone  and  the 
sagittal  suture  of  the  parietal  bones,  back  upon  the  upper 
half  of  the  vertical  ridge  of  the  occipital  bone,  to  the  ten- 
torium, upon  which  it  rests  and  with  which  it  is  continu- 
ous; as  it  ascends  it  describes  a  curve,  increasing  in  depth 
as  it  proceeds  upward,  having  its  superior  border  broad 
and  convex,  containing  the  superior  longitudinal  sinus, 
while  its  inferior  is  sharp  and  concave,  enclosing  the  infe- 
rior longitudinal  sinus. 

The  tentorium  is  stretched  horizontally  across  the  inferior 
part  of  the  cranium,  separating  the  cerebrum  from  the 
cerebellum.  It  is  seen  by  lifting  the  posterior  lobes  of  the 
cerebrum,  and  is  connected  by  its  convex  border  to  the 
transverse  ridge  and  tubercle  of  the  occipital  bone,  the 
inferior  posterior  angle  of  the  parietal,  the  superior  ridge 
of  the  petrous,  and  the  clinoid  processes  of  the  sphenoid. 
The  tentorium  is  convex  above  and  concave  below,  and 
derives  its  name  from  its  being  arched  in  the  centre  like  a 
tent.  Along  its  convex  border  are  the  two  lateral  sinuses, 
and  upon  its  median  line  is  the  straight  sinus.  At  its 
anterior  part  is  a  large  oval  foramen  occupied  by  the  pons 
Varolii,  crura  cerebri,  and  the  superior  vermiform  process 
of  the  cerebellum. 

The  falx  cerebelli  is  situated  below  the  tentorium,  upon 
the  inferior  occipital  ridge,  and  separates  the  hemispheres 


396  SINUSES  OF  THE  DURA  MATER. 

of  the  cerebellum.  Its  convex  border  encloses  the  two 
occipital  sinuses.  Its  direction  is  vertical,  extending  from 
the  tentorium  above,  to  the  foramen  magnum  below.  Other 
reflections  of  the  dura  mater,  called  sphenoidal  folds,  are 
seen  on  the  sides  of  the  sella  turcica,  forming  the  cavernous 
sinuses. 

<  Sinuses  of  the  dura  mater,  (Fig.  112.) — All  the  sinuses 
are  formed  by  reflections  of  the  internal  lamina  of  the  dura 
mater,,  separating  from  the  external,  and  leaving  large 
triangular  cavities  between  them,  lined  with  the  same 
membrane  as  that  of  the  veins,  all  communicating  with 
each  other,  and  designed  for  receiving  the  venous  blood  of 
the  brain.  As  many  as  fifteen  sinuses  are  enumerated; 
five  of  these  being  in  pairs  and  five  single.  Those  in  pairs 
are  the  two  lateral,  two  superior  petrosal,  two  inferior  petro- 
sal, two  occipital,  and  two  cavernous.  The  single  are  the 
superior  and  inferior  longitudinal,  the  straight,  transverse 
and  circular.  Others  again  make  only  eight,  while  Mr. 
Tuson  gives  nine,  which  is  the  most  commonly  received 
number.  They  are  the  following: 

1.  Superior  longitudinal  sinus.  2.  Inferior  longitudinal 
sinus.  3.  Two  lateral  sinuses.  4.  Vena  magna  Galeni. 
5.  The  superior  petrosal  sinus.  6.  Inferior  petrosal  sinus. 
V.  The  two  carvernous  sinuses.  8.  Circular  sinus  of  Kid- 
ley.  9.  Torcular  Herophili. 

In  this,  however,  it  will  be  seen  there  is  no  mention  of 
the  occipital  sinuses.  The  superior  longitudinal  sinus,  as 
just  stated,  describes  the  course  of  the  superior  margin  of 
the  falx  major  ;  when  opened  its  form  is  seen  to  be  trian- 
gular, its  base  being  above  and  its  apex  below,  in  the  falx — 
little  fibres  called  cordon-  Willisii,  are  seen  to  cross  it  in 
different  places ;  numerous  orifices  are  seen  throughout 
the  whole  extent  of  this  sinus,  corresponding  to  the  en- 
trance of  the  veins  from  the  cerebral  hemispheres,  dura- 
mater,  diploe,  and  pericranium. 

The  glandular  Pacchioni  are  seen  connected  with  this 
sinus  in  two  positions,  first  on  the  outside  of  the  dura  mater 
and  near  the  sinus;  and  second  within  the  sinus.  They  are 


SINUSES  OF  THE   DURA   MATER. 


397 


F.o.  112. 


also  found  upon  the  arach- 
noid membrane.  These 
glands,  as  they  are  called, 
consist  of  small,  round, 
whitish  bodies,  found  in 
clusters  or  singly,  and 
varying  in  number,  size, 
and  appearance. 

The  inferior  longitudi- 
nal sinus  resembles  a  vein, 
and  receives  the  veins  of 
the  corpus  callosum.  It 
ends  in  the  straight  sinus. 
The  two  lateral  sinuses 
are  the  largest,  and  formed 
by  the  junction  of  the  lon- 
gitudinal and  straight. 
They  commence  at  the  in- 
ternal occipital  protuber- 
ance, course  outward  along 
the  convex  border  of  the 
tentorium,  within  the  hor- 
izontal occipital  groove, 
thence  along  the  channel 
in  the  mastoid  portion  of 
the  temporal  bone,  and  finally  pass  out  of  the  skull  at  the 
foramen  lacerum  posterius  to  become  the  internal  jugular 
veins  of  the  neck. 

The  vein  of  Galen  corresponds  to  the  rectus  or  straight 
sinus  which  is  situated  between  the  laminae  at  the  base  of 
the  falx  major,  where  it  rests  upon  the  tentorium.  It  receives 

FIG.  112,  A  represents  the  sinuses  of  the  dura-mater,  a  Superior  longitudinal 
sinus.  6  Inferior  longitudinal  sinus,  both  of  these  sinuses  are  in  the  falx  cere- 
bri.  c  Veins  of  galen.  d  Rectus  or  straight  sinus,  e  Torcular  Herophili. 

FIG.  112,  B  represents  the  sinuses  at  the  base  of  the  cranium.  1  Opening 
of  superior  longitudinal  sinus  into  the  torcular  Herophili.  2  Left  lateral  sinus. 
d  Where  the  jugular  vein  commences,  e  Superior  petrosal  sinus.  /Cavern- 
ous sinus,  g  Ophthalmic  vein,  h  Transverse  sinus,  i  Circular  or  coronary 
sinus  of  Ridley. 


398  TUNICA  ARACHNOIDEA. 

the  veins  of  the  septum  lucidum,  choroid  plexus,  corpora 
striata,  and  other  inner  portions  of  the  brain,  and  termin- 
ates at  the  junction  of  the  longitudinal  and  straight  sinus. 

The  petrosal  sinuses  are  four  in  number,  two  on  each  side. 
The  superior  are  between  the  superior  grooved  ridge  of  the 
petrous  bone  and  tentorium,  the  inferior  at  the  root  of  the 
petrous  bone,  and  both  discharge  into  the  lateral  sinuses. 

The  cavernous  sinuses  are  situated  upon  the  sides  of  the 
sella  turcica,  receive  the  ophthalmic  veins  anteriorly,  and 
connect  posteriorly  with  the  petrosal  sinuses.  Tendinous 
fibres  are  seen  intersecting  this  sinus,  and  through  it 
pass  the  internal  carotid  artery,  the  third,  fourth,  first 
branch  of  the  fifth  and  sixth  nerves. 

The  circular  sinus  of  Ridley  is  situated  in  front  and  be- 
hind the  pituitary  body,  almost  surrounding  it,  and  con- 
nected with  the  cavernous. 

The  torcular  Heropliili  is  situated  upon  the  internal 
occipital  protuberance,  and  forms  the  common  point  of 
junction  of  the  longitudinal,  lateral,  straight,  occipital  and 
transverse  sinuses 

The  occipital  sinuses  are  situated  in  the  falx  cerebelli, 
receive  veins  from  the  spinal  canal,  cerebellum,  and  adja- 
cent bone,  and  terminate  in  the  torcular  Herophili. 

The  transverse  sinus  extends  across  the  cuneiform  pro- 
cess of  the  occipital  bone,  and  connects  with  the  petrosal, 
cavernous,  and  lateral  sinus  of  opposite  sides. 

The  tunica  araclmoidea  forms  the  second  covering  of  the 
brain,  and  is  continuous  with  that  of  the  spinal  marrow. 
Like  all  serous  membranes,  it  forms  a  shut  sac,  one  portion 
of  it  covering  the  brain,  called  visceral,  the  other,  or 
parietal,  is  reflected  upon  the  dura  mater.  It  presents  the 
usual  smooth,  shining,  transparent,  and  ,delicate  appear- 
ance of  serous  membranes  in  general.  Its  extent  is  com- 
mensurate with  the  whole  external  surface  of  the  brain, 
covering  all  its  convolutions,  but  not  dipping  down  between 
them.  It  also  lines  the  interior  of  the  dura  mater,  and 
can  be  traced  into  the  ventricles  lining  their  internal  sur- 
face. The  point  at  which  this  membrane  is  seen  to  enter 


PIA  MATER   OP   THE  BRAIN.  399 

the  ventricles  is  beneath  the  posterior  lobes  of  the  cere- 
brum, in  front  of  the  anterior  edge  of  the  tentorium,  and 
below  the  veins  of  Galen,  where  will  be  noticed  a  small 
foramen  or  canal,  leading  forward  above  the  pineal  gland, 
and  opening  into  the  third  ventricle.  The  arachnoid  is 
more  loosely  attached  at  some  points  than  others,  leaving 
spaces,  which  are  named  according  to  their  locations,  as 
the  anterior,  posterior,  lateral,  and  superior  sub-arachnoid 
spaces. 

Function. — To  secrete  a  fluid  serum  which  lubricates  its 
surfaces,  and  prevents  friction.  When  this  fluid  is  in 
excess  in  the  arachnoid  cavity,  that  is,  between  its  parietal 
and  visceral  portions,  it  constitutes  that  variety  of  dropsy 
known  by  the  name  of  hydrocephalus  externus ;  if  the  ex- 
cess be  in  the  ventricles,  it  is  called  hydrocephalus  internus. 
It  gives  also  a  sheath  to  the  veins  as  they  enter  the  supe- 
rior longitudinal  sinus,  and  a  covering  to  the  nerves  as 
they  leave  the  brain. 

The  pia  mater  forms  the  third  and  innermost  membrane 
of  the  brain.  It  differs  from  the  spinal,  with  which  it  is 
continuous  in  being  vascular  instead  of  fibrous.  It  is  im- 
mediately in  apposition  with  the  brain,  and  is  much  more 
extensive  than  the  arachnoid ;  for  it  not  only  covers  the 
whole  of  the  external  surface  of  all  the  convolutions,  but 
dips  down  between,  covering,  every  where,  the  external 
gray  matter,  and  finally  entering  the  ventricles,  and  there 
forming  folds,  such  as  the  choroid  plexuses,  &c. 

It  can  be  drawn  out  from  between  the  various  convolu- 
tions and  expanded,  when  it  presents  the  appearance  of  an 
extremely  delicate  membrane  loaded  with  vessels;  hence 
its  structure  is  regarded  as  essentially  vascular.  It  is  the 
nutritious  membrane  of  the  brain,  the  capillary  arteries 
passing  from  it  into  the  brain,  and  the  veins  going  from  it 
into  the  sinuses.  Its  external  surface  is  in  relation  with 
the  arachnoid,  to  which  it  is  closely  and  inseparably  at- 
tached upon  the  surface  of  the  convolutions,  while  at  the 
base  of  the  brain,  and  in  the  different  sulci,  between  the  sev- 
eral convolutions,  they  are  distinct  and  readily  separated. 


400  MEDULLA  OBLONGATA. 

Its  internal  surface,  as  stated,  is  in  contact  with  the  brain_, 
und  united  to  it  by  the  immense  number  of  vessels  passing 
from  it  into  its  substance. 

MEDULLA   OBLONGATA.    (Fig.  16.) 

The  medulla  oblongata,  or  racliidian  bulb,  is  situated  upon 
the  cuneiform  process  of  the  occipital  bone,  occupying  its 
concave  surface,  and  forming  the  upper  portion  of  the  spi- 
nal marrow.  It  extends  from  the  atlas,  or  first  vertebra, 
to  the  pons  Varolii,  being  represented  as  from  "  fourteen  to 
fifteen  lines  in  length,  nine  lines  in  breadth,  3-nd  six  in 
thickness."  Its  shape  is  conical,  the  base  being  above,  the 
apex  below.  Like  the  spinal  marrow,  it  has  a  median  fis- 
sure in  front  and  behind,  dividing  it  into  two  lateral  and 
symmetrical  parts,  each  of  which  is  again  divided  by  three 
grooves,  presenting  upon  its  surface  four  eminences:  the 
corpora  pyramidalia,  corpora  olivaria,  corpora  restiformia, 
and  posterior  pyramids. 

According  to  Mr.  Solly,  each  lateral  half  of  the  spinal 
marrow  consists  of  antero-lateral  and  posterior  columns; 
the  antero-lateral  being  again  divided  into  two  portions, 
not  by  any  anatomical  separation,  but,  he  says,  "physio- 
logically;" the  half  or  two-thirds  of  the  anterior  part 
being  the  motor  tract,  and  corresponding  to  the  corpora 
pyramidalia  and  olivaria  of  the  medulla  oblongata,  each  of 
which  sends  fibres  to  the  cerebrum  and  cerebellum,  while 
the  balance  of  the  antero-lateral  column,  with  the  poste- 
rior, is  for  sensation. 

The  anterior  median  fissure  of  the  medulla  oblongata  is 
broader  but  not  so  deep  as  the  spinal,  of  which  it  is  a  con- 
tinuation. It  is  lined  by  the  pia  mater,  and  is  connected 
by  transverse  commissural  fibres.  About  an  inch  below 
the  pons,  this  fissure  is  obstructed  by  the  fasciculi  of  the 
anterior  columns  of  the  spinal  marrow,  crossing  or  decus- 
sating each  other  at  the  lower  end  of  each  pyramid.  This 
decussatlon  explains  why  injuries  upon  one  side  of  the 
brain  affect  the  opposite  side  of  the  body;  but  as  all  the 
fibres  do  not  cross  over,  this  further  explains  the  occa- 


MEDULLA  OBLONGATA.  401 

sional  exceptions,  when  the  injury  is  felt  on  the  same 
side. 

The  Corpora  pyramidalia}  or  anterior  pyramids,  are  sit- 
uated upon  either  side  of  the  median  fissure,  extending  the 
whole  length  of  the  medulla  oblongata,  and  represent  two 
white,  convex,  and  narrow  bands,  placed  side  by  side. 
They  each  arise  at  the  point  of  decussation,  as  above  stated, 
by  two  sets  of  fibres — the  one  from  the  opposite  anterior 
column  of  the  spinal  marrow — the  other  from  the  same 
side  with  itself.  As  they  enter  the  pons  they  become  con- 
stricted, and  can  be  traced  through  it  to  the  crura  cerebri, 
forming  their  outer  and  anterior  portions. 

Corpora  Olivaria,  so  named  from  their  resemblance  to  an 
olive,  are  situated  to  the  outside  of  the  corpora  pyramid- 
alia,  are  shorter,  and  more  convex  than  the  pyramids,  and 
separated  from  them  and  the  restiform  bodies  by  a  groove. 
They  consist  of  two  beautiful  white  bodies,  which  proceed 
from  the  antero  lateral  column  of  the  spinal  marrow,  and 
continue  through  the  central  portion  of  the  medulla  ob- 
longata, extending  to  its  posterior  surface,  forming  the 
floor  of  the  fourth  ventricle.  These  bodies  can  be  traced  as- 
cending behind  the  corpora  pyramidalia,  through  the  pong, 
to  the  posterior  portions  of  the  crura  cerebri,  and  thence  to 
the  tubercula  quadrigemina,  and  optic  tlialami.  Some  curved 
fibres,  termed  arciform,  pass  over  the  corpora  olivaria  from 
the  pyramids  to  the  corpora  restiformia ;  they  vary  in  num- 
ber and  size,  and  are  regarded  as  commissural  between  the 
bodies  with  which  they  are  connected. 

The  olivary  bodies  are  found  to  exist  only  in  man  and 
the  quadrumana.  On  being  divided,  a  quantity  of  gray 
matter  is  seen,  called  the  olivary  ganglion. 

The  Corpora  Eestiformia  (restis,  a  rope)  are  situated 
upon  the  side  and  posterior  part  of  the  medulla  oblongata, 
separated  from  the  corpora  olivaria  by  a  groove,  and  from 
each  other  superiorly  by  the  fourth  ventricle,  and  inferi- 
orly  by  the  posterior  median  fissure.  They  are  continuous 
with  the  posterior  and  part  of  the  antero  lateral  columns 
of  the  spinal  cord,  and  are  traced  ascending  and  diverging 
26 


402  PONS  VAROLIL 

to  the  cerebellum.  The  corpora  restiformia  thus  form  the 
line  of  connection  between  the  spinal  marrow,  medulla 
oblongata,  and  cerebellum.  Mr.  Solly  calls  these  bodies 
ganglia  restiformia,  or  the  ganglia  of  the  pneumogastric 
nerves. 

The  Posterior  pyramids  are  seen  on  the  back  part  of  the 
cord  on  either  side  of  the  posterior  fissure,  in  relation  with 
the  fourth  ventricle,  and  continuous  partly  with  the  resti- 
form,  and  partly  with  the  posterior  olivary  bodies.  They 
are  found  to  commence  as  low  down  as  the  dorsal  region, 
and  to  ascend  as  high  as  the  fourth  ventricle.  They  are 
viewed  as  commissural  to  the  spinal  cord  and  medulla  ob- 
longata. These  posterior  pyramids  are  also  called  auditory 
ganglia.  The  medulla  oblongata,  thus  composed,  is  justly 
regarded  as  a  most  important  ganglionic  centre,  or  as  Mr. 
Solly  thinks,  of  six  ganglia,  three  on  either  side  of  the 
fissure,  i.  e.  the  anterior,  lateral,  and  posterior,  in  addition 
to  the  columns  for  motion  and  sensation. 

Nerves  of  the  Medulla  Oblongata. — Between  the  pyramids 
and  olivary  are  the  ninth  nerves,  between  the  olivary  and 
the  restiform  bodies  are  the  eighth  pair.  From  the  oli- 
vary, by  the  side  of  the  calamus  scriptorius,  are  the  audi- 
tory. The  fifth  can  be  traced  also  into  the  olivary,  and 
the  sixth  are  between  the  pyramids  and  pons. 

PONS  VAROLII. 

The  Pons  Varolii,  or  tuber  annulare,  (Fig.  16,)  so  called 
from  its  arched  or  bridge-like  form  and  its  discoverer,  is 
a  white  body,  situated  upon  the  top  of  the  medulla  ob- 
longata, about  the  centre  of  the  base  of  the  brain,  and 
between  the  cerebrum  and  cerebellum. 

It  rests  upon  the  cuneiform  process  of  the  occipital  bone 
at  its  junction  with  the  sphenoid,  by  its  inferior  and  ante- 
rior surface.  Its  superior  and  posterior  surfaces  are  in  rela- 
tion with  the  tubercula  quadrigemina,  the  fourth  ventricle, 
and  the  aqueduct  of  Sylvius.  The  crura  cerebri  are  con- 
nected to  its  upper  extremity,  the  crura  cerebelli  to  its  sides, 
and  the  medulla  oblongata  to  its  lower  extremity.  Its  in- 


CEREBELLUM.  403 

ferior  surface  is  divided  by  a  median  groove,  which,  receives 
the  basilar  artery. 

Its  structure  externally  is  fibrous  or  medullary,  and 
white;  the  superficial  fibres  on  the  lower  surface,  run 
transversely  from  the  crus  cerebelli  on  the  one  side,  to  the 
crus  on  the  opposite  side,  thus  making  the  pons  the  great 
commissure  of  the  cerebellum.  Beneath  these  transverse 
fibres,  after  turning  them  aside,  is  seen  a  quantity  of  cin- 
eritious  matter,  through  which  pass  medullary  fibres  corre- 
sponding to  the  pyramidal  tracts,  intermingling  with  the 
transverse  fibres,  and  proceeding  onward  to  the  crura  cerebri. 

The  size  of  the  pons  is  always  found  to  be  in  direct  pro- 
portion to  the  hemispheres  of  the  cerebellum.  When  the 
cerebellum  is  very  small  or  entirely  wanting,  the  pons  is 
likewise  proportionally  small  or  wholly  absent.  This  fact 
is  confirmed  by  comparative  anatomy,  as  in  birds,  fishes 
and  reptiles,  the  cerebellum  being  entirely  wanting  or 
only  rudimental,  the  pons  is  equally  wanting. 

The  pons  is  so  connected  with  the  -medulla  oblongata, 
cerebellum,  and  cerebrum,  as  to  be  regarded  as  having  a 
common  relation  to  the  whole. 

CEREBELLUM — LESSER  OR  INFERIOR  BRAIN.    (Fig.  113.) 

Dissection. — Kaise  the  posterior  lobes  of  the  cerebrum,  or 
remove  them  entirely,  and  divide  the  tentorium,  when  the 
cerebellum  will  be  exposed. 

It  is  situated  beneath  the  tentorium  in  the  inferior  oc- 
cipital fossae.  Its  size  is  estimated  to  be  seven  times 
smaller  than  the  cerebrum,  and  according  to  Grail,  larger 
in  the  female  than  the  male.  The  average  weight  is  about 
four  ounces  and  a  half.  Its  form  is  that  of  an  "ellip- 
soid"— oval  in  the  transverse  diameter,  and  measuring 
from  three  and  a  half  to  four  inches  in  this  direction. 
Its  antero-posterior  diameter  is  from  two  to  two  and  a 
half  inches,  and  its  vertical,  in  the  thickest  part,  about 
two  inches.  It  is  divided  into  two  lateral  and  sym- 
metrical parts  called  hemispheres.  This  division  is  made 
by  the  anterior  and  posterior  median  fissurSj  or  notches, 


404 


CEREBELLUM. 


FIG.  113. 


the  latter    of  which   contains    the    falx    cerehelli.     The 
posterior  fissure,  from  its  great  depth,  receives  the  name 

also  of  the  valley, 
or  purse-like  fis- 
sure. The  ante- 
rior one  is  broad, 
encloses  the  tu- 
bercula  quadri- 
gemina,  and  over- 
laps the  fourth 
ventricle.  Each 
hemisphere  is 
again  divided  in- 
to lobes  and  lob- 
ules by  the  various 
sulci  and  furrows 
on  its  surfaces. 
Its  surfaces  are 
two — superior  and 
inferior. 

The  superior 
surface  is  marked 
bylines  or  furrows 
which  are  concen- 
tric, presenting 
the  form  of  large 
curves,  parallel  and  concave  forward.  In  the  middle  line, 

FIG.  113,  A  represents  the  superior  surface  of  the  Cerebellum.  1  1  Lat- 
eral lobes  or  hemispheres.  2  2  Anterior  or  square  lobes.  3  3  Posterior  or 
semicircular-shaped  lobes.  4  4  Inferior  semilunar  lobe— its  internal  part. 
5  6  Superior  vermiform  process.  7  The  deep  posterior  fissure,  separating  the 
hemispheres,  and  covered  by  medulla  oblongata,  called  the  valley,  or  purse- 
like  fissure.  8  Pons  Varolii.  9  Superior  fossa  of  cerebellum. 

FIG.  113,  B  represents  the  inferior  surface  of  the  Cerebellum.  1  1  Lateral 
hemispheres,  or  lobes.  2  2  External  and  front  portions  of  anterior  lobes.  3  3 
Great  horizontal  fissure.  4  4  The  posterior  or  semilunar  lobes.  5  5  Gracilis, 
or  slender  lobes.  6  6  Digastric,  or  anterior  and  external  lobes.  7  7  Amyg- 
daloid, or  tonsillitic  lobes.  8  8  Flocculus,  or  Pneumogastric  lobes.  9  9  White 
substance  of  floccujus.  11  Inferior  vermiform  process.  12  Nodule.  13  Pyr- 
amid. 14  Pons  Varolii.  15  15  Crura  cerebelli. 


CEREBELLUM.  405 

and  most  prominent  in  front,  is  a  ridge  or  process,  called 
the  superior  vermiform  process,  or  middle  superior  lobe, 
which  is  related  with  the  valve  of  Yieussens — covers  the 
tubercula  quadrigemina,  and  connects  the  lateral  lobes. 
One  deep  sulcus  divides  the  superior  surface  of  each  hemi- 
sphere into  an  anterior  and  posterior  lobe.  The  anterior 
stretches  as  far  forward  as  the  anterior  notch,  and  is  con- 
nected to  its  fellow  by  the  transverse  fibres  of  the  superior 
vermiform  process.  The  posterior  extends  to  the  convex 
border  behind,  and  is  also  connected  by  transverse  fibres. 
Both  of  these  lobes  are  again  divisible  into  smaller  parts 
consisting  of  lobules,  and  laminae,  or  leaflets. 

The  inferior  surface,  like  the  superior,  is  also  marked  by 
concentric  lines,  furrows,  or  sulci.  It  is  divided  from  the 
superior  by  a  horizontal  fissure,  which  is  deep  and  extends 
round  the  circumference  of  both  hemispheres,  as  far  for- 
ward as  the  pons.  This  fissure  is  lined  by  pia  mater,  and 
has  its  floor  covered  with  medullary  matter,  which  can  be 
traced  into  the  crura  cerebelli. 

When  the  membranes  are  removed,  the  furrows  of  both 
surfaces  are  found  to  differ  from  those  of  the  cerebrum,  in 
having  their  bases  closed  with  the  white  neurine,  instead 
of  the  gray. 

The  lower  surface  which  is  very  convex,  has  been  divided 
by  anatomists  into  as  many  as  five  lobes,  distinguished  as 
follows :  The  anterior  and  internal,  called  also  the  amyg- 
daloid, or  tonsillitic;  the  anterior  external,  or  the  digastric; 
the  posterior,  or  semilunar;  the  pneumogastric  lobe,  or  floc- 
culus ;  the  anterior  inferior,  and  the  middle  lobe,  or  gracilis. 
The  names  of  these  several  lobes  define  pretty  well  their 
location.  The  tonsil,  or  anterior  internal  lobe,  is  covered 
by  the  medulla  oblongata,  and  projects  into  the  fourth  ven- 
tricle, at  its  sides  and  posterior  part. 

The  pneumogastric  lobe  is  near  the  origin  of  the  eighth 
pair  of  nerves — hence  its  name. 

In  the  median  fissure,  on  the  inferior  surface,  is  seen  a 
pyramidal  projection,  divided  into  rings  transversely,  and 
called  the  inferior  vermiform  process,  which  unites  the 


406  CEREBELLUM. 

hemispheres  below.  The  superior  and  inferior  vermiform 
processes,  though  distinguished  by  different  names;  are 
regarded  as  essentially  one  and  the  same  lobe,  as  they 
are  continuous,  the  one  with  the  other,  and  have  been 
called  the  median  lobe,  or  primitive  lobe  of  the  cerebel- 
lum. 

This  primitive  lobe  is  found  to  be  the  only  portion  present 
in  fish  and  reptiles,  while  in  birds  the  hemispheres  consist 
simply  of  small  lateral  offsets  from  this  central  fundamental 
part. 

Upon  the  inferior  vermiform  process,  three  little  emi- 
nences have  received  names,  the  most  anterior  being  called 
the  nodule;  the  middle,  the  uvula;  and  the  posterior,  the 
pyramid. 

.  FIG.  114.  The  cerebellum  consists  of 

cineritious,  or  gray  matter 
externally,  and  white  or 
medullary  internally.  In 
making  a  horizontal  section, 
a  large  white  central  me- 
dullary mass  is  seen,  which 
can  be  traced  from  the  one 
hemisphere  to  the  other.  In 
a  vertical  section,  a  beauti- 
ful arrangement  of  the  med- 
ullary striae,  resembling  the  branches  of  a  tree,  is  seen,  and 
hence  called  arbor  vitce.  If  the  vertical  incision  be  made  upon 
the  outer  third  of  the  hemisphere,  there  will  be  noticed  in  the 
interior  of  the  white  central  ma$s,  a  small  yellowish  or  gray 

FIG.  114  represents  the  arbor-vita  of  the  cerebellum,  a  Tubercula  quadri- 
gemina.  6  Superior  surface  of  the  cerebellum,  c  Inferior  surface  and  arbor 
vitee  ;  from  the  trunk  of  this  latter  three  fasciculi  are  traced  to  the  tubercula 
quadrigemina,  the  most  internal  of  these  fasciculi  is,  d  A  fibrous  layer  ;  on  the 
outside  of  this  is,  e  The  next  fasciculus,  and  on  the  outside  of  this  again  is, 
/The  third  fasciculus,  g  A  thin  medullary  layer  passing  from  the  crus  cerebelli 
to  the  cerebrum,  h  Anterior  extremity  of  fourth  ventricle,  i  Middle  furrow  on 
the  floor  of  fourth  ventricle,  j  Tracts  of  nervous  matter  leading  to  the  audito- 
ry nerve,  k  Nervous  matter  presenting  a  raised  appearance  on  the  floor  of 
fourth  ventricle.  I  Middle  fissure  in  calamus  scriptorius.  m  Corpora-restifor- 
mia.  n  A  side  view  of  the  spinal  marrow. 


CEREBELLUM.  407 

body,  called  the  corpus  dentatum  or  rliomboideum,  or  ganglion 
of  the  cerebellum.  This  ganglion  receives  the  greater  part 
of  the  corpus  restiforme,  and  with  the  central  medullary  por- 
tion in  which  it  is  found,  is  connected  with  the  medulla  ob- 
longata,  pons  Yarolii,  and  cerebrum.  Three  processes  on 
each  side  establish  this  connection :  1.  The  inferior  process 
or  peduncle,  corpus  restiforme^  which  extends  from  the 
posterior  column  of  the  medulla  oblongata,  to  this  central 
portion  of  the  cerebellum.  2.  The  anterior  peduncle  or  crus 
cerebellij  which  proceeds  from  the  floor  of  the  horizontal  fis- 
sure on  either  side,  and  passing  forward  and  inward,  meets 
with  its  fellow  of  the  opposite  side  to  form  the  anterior  layer 
of  the  pons  or  great  commissure  of  the  cerebellum,  and  3. 
The  superior  peduncle,  or  processus  a  cerebello  ad  testes. 
These  are  two  white,  thick,  medullary  bands,  which  are 
traced  from  the  corpus  dentatum  of  each  hemisphere,  and 
ascend  above  the  crura  cerebelli,  to  join  the  testes.  They 
form  part  of  the  lateral  boundaries  of  the  fourth  ventricle, 
and  are  connected  to  each  other  by  the  valve  of  Vieussens, 
which  together  act  as  commissures,  both  between  the  cere- 
brum and  cerebellum,  as  well  as  between  the  hemispheres 
of  the  cerebellum  and  the  median  lobe. 

The  fourth  ventricle  generally  described  as  belonging  to 
the  cerebellum,  is  rather  considered  a  ventricle  of  the  me- 
dulla oblongata.  It  is  situated  upon  the  posterior  surface 
of  the  medulla  oblongata,  having  the  pons  in  front,  the 
median  lobe  of  the  cerebellum  behind,  and  its  hemispheres 
laterally.  It  appears  as  a  considerable  cavity  of  a  quadri- 
lateral shape,  about  an  inch  and  a  half  in  length,  and  of 
nearly  the  same  breadth. 

The  superior  angle  of  this  ventricle  leads  into  the  aque- 
duct of  Sylvius;  the  inferior  corresponds  with  the  posterior 
median  fissure  of  the  cord. 

On  the  anterior  and  inferior  wall  of  this  ventricle  is  a 
median  groove,  distinct  and  sharp,  and  from  its  resem- 
blance to  a  writing  pen,  has  been  called  calamus  scriptorius. 
On  either  side  are  white  striae,  the  linece  transversce  forming 
the  feathers  of  the  pen  and  being  the  origin  of  the  auditory 


408  CEREBRUM. 

nerve  or  portio  mollis.     This  cavity  is  lined  in  most  of  its 
extent  by  gray  neurine. 

CEREBRUM  OR  UPPER  BRAIN. 

The  Cerebrum,  (Fig.  16,)  styled  the  brain  proper,  is  sit- 
uated- within  the  cranial  cavity,  occupying  the  whole  of 
this  cavity  extending  from  the  vault  to  the  tentorium,  by 
which  latter  it  is  separated  from  the  lower  brain  or  cere- 
bellum. 

It  is  about  seven  times  heavier  than  the  cerebellum, 
weighing  from  two  and  a  half  to  three  pounds.  The  brain 
of  man  is  heavier  than  that  of  any  other  animal.  Its 
form  is  oval,  and  its  average  diameters  are  as  follow :  the 
antero  posterior  about  six  inches,  the  transverse  in  its 
greatest  breadth  about  five,  and  the  vertical  between  four 
and  five.  It  is  divided  into  two  lateral  and  symmetrical 
parts  by  a  deep  fissure  which  runs  along  the  median  line, 
separating  the  cerebrum  in  its  whole  depth,  but  inter- 
rupted by  the  corpus  callosum  in  the  middle.  This  fissure 
receives  the  falx  major  and  the  anterior  and  cerebral  arte- 
ries and  veins,  and  the  two  lateral  portions  thus  divided 
are  called  hemispheres.  Each  hemisphere  is  again  divided 
into  three  lobes,  an  anterior,  middle,  and  posterior  lobe. 
The  anterior  or  frontal  lobes  are  small  and  are  situated 
upon  the  orbitar  plates  of  the  frontal  bone.  The  middle 
or  temporal  are  large  and  prominent,  occupy  the  middle 
fossa  in  the  base  of  the  cranium,  and  are  separated  from 
the  anterior  by  the  deep  fissure  of  Sylvius.  This  fissure 
receives  the  middle  cerebral  arteries. 

The  posterior  lobes  rest  upon  the  tentorium,  having  but 
a  slight  mark  of  separation  from  the  middle,  which  how- 
ever corresponds  to  the  superior  ridge  of  the  petrous  bone. 
The  surfaces  of  the  cerebrum  are  superior,  inferior,  and 
lateral.  Its  general  form  has  just  been  stated  to  be  oval, 
but  as  it  exactly  corresponds  with  the  cranial  cavity,  its 
shape  will  vary  with  the  shape  of  this  cavity.  The  form 
of  the  superior  surface  is  convex,  corresponding  to  the 
concave  vault  of  the  cranium — the  inferior  is  flat;  adapted 


CEREBRUM.  409 

to  the  base,  while  the  lateral  surfaces  are  also  a  little  flat- 
tened. All  the  surfaces  of  the  cerebrum  are  marked  by 
distinct  eminences,  which,  from  their  turnings  and  resem- 
blance to  the  intestines,  are  called  convolutions,  (Fig.  115, 
A,)  while  the  deep  furrows  every  where  seen  separating  the 
convolutions  are  named  anfractuosities ,  and  range  from  a 
quarter  to  an  inch  and  a  half  in  depth. 

The  surface  of  the  convolutions  presents  a  smooth  and 
polished  appearance,  from  the  presence  and  covering  of  the 
arachnoid  membrane.  "  A  convolution  is  defined  to  be  a 
convex  fold  of  superficial  gray  neurine,  covered  all  round 
to  its  base  by  pia  mater ;  and  a  sulcus  is  a  depression  or  in- 
volution between  any  two  or  more  convolutions,  and  lined 
by  a  continuation  of  the  gray  lamina." 

The  convolutions  are  very  varied,  both  in  their  form  and 
number,  and  though  seemingly  on  first  view  distinct,  yet 
they  really  are  continuous  with  and  run  into  each  other, 
though  there  is  nevertheless  a  close,  if  not  a  perfect  sym- 
metry between  those  of  opposite  sides. 

These  convolutions  constituting  the  cortical  portion,  are 
called  by  Mr.  Solly  the  hemispherical  ganglia,  and  their 
structure  does  not  consist,  he  says,  of  a  single  layer  of  gray 
or  cortical  matter,  but  according  to  the  microscopic  obser- 

FIG.  115.  A 


vations  of  M.  Baillarger,  of  six  layers,  three  layers  of 
the  gray,  alternating  with  three  of  the  white,  (Fig.  115,  B.) 
Counting  from  within,  the  first  is  represented  as  gray,  the 

FIG.  115,  A  represents  the  convolutions  of  one  side  of  the  cerebrum,  a  An- 
terior lobe  of  cerebrum.  6  Posterior  lobe,  c  Middle  lobe. 

FIG.  115,  B  represents  the  six  alternate  layers  of  gray  and  white  neurine, 
composing  a  convolution  of  the  human  brain. 


410  CEREBRUM. 

second  white,  the  third  gray,  the  fourth  white,  the  fifth 
gray,  and  the  sixth  white.  The  outermost  or  cortical  layer, 
which  to  the  eye  is  cineritious,  is  thus  seen  to  he,  under  the 
glass,  white,  and  this  seems  also  to  accord  with  the  obser- 
vations of  Mr.  Grainger,  thus  reversing  the  supposed  order 
of  the  several  layers. 

In  the  posterior  convolutions  the  distinction  between 
some  of  these  layers  has  been  frequently  seen  with  the 
naked  eye.  The  tubular  fibres  from  the  hemispheres  pass 
through  these  layers,  and  in  relation  to  the  convolutions 
are,  according  to  Mr.  Solly,  arranged  in  four  different  ways, 
"first,  some  of  them  commencing  from  the  convolutions  of 
the  anterior,  middle,  and  posterior  lobes,  pass  through  the 
corpora  striata,  and  forming  the  inferior  layer  of  the  crus 
cerebri,  pass  through  the  pons  Yarolii,  so  as  to  form  the  an- 
terior columns  of  the  spinal  cord,  the  motor  tract ;  second, 
others  commencing  in  the  nerves  of  sensation,  after  pass- 
ing through  the  pons  Varolii,  and  emerging  from  the 
substance  of  the  thalamus,  terminate  in  the  same  convolu- 
tions, constituting  the  sensory  tract ;  third,  others  passing 
from  one  side  of  the  brain  to  the  other,  and  in  apposition  to 
the  internal  surface  of  all  the  convolutions,  are  those  fibres 
which,  collected  into  a  mass,  form  between  the  hemispheres 
that  wide  bridge,  the  great  transverse  commissure  or  corpus 
callosum,  to  be  presently  described ;  fourth,  in  contact  with 
all  the  convolutions  are  the  fibres  of  the  superior  and  in- 
ferior longitudinal  commissures,  which  connect  together 
those  convolutions  which  are  situated  on  the  same  side  of 
the  mesial  line  or  different  portions  of  the  same  hemi- 
spherical ganglion." 

Those  fibres  going  from  the  anterior  and  posterior  col- 
umns of  the  cord,  as  from  a  common  centre  and  spreading 
out  upon  the  convolutions,  are  called  by  Gall  and  Spurzheim 
the  diverging  fibres.  While  those  proceeding  from  the  con- 
volutions towards  the  centre  of  the  brain  are  named  con- 
verging fibres. 

The  convolutions  are  distinguished  into  primary  and 
secondary.  The  primary  are  those  which  are  found  to  be 


CEREBRUM.  411 

more  generally  present,  and  to  exist  in  the  inferior  animals. 
They  are  generally  longitudinal  in  their  direction,  while 
the  secondary  are  found  to  be  mostly  transverse.  One  of 
the  most  regular  of  the  primary  convolutions,  is  the  long 
curved  one  situated  on  the  inner  or  mesial  side  of  each 
hemisphere  above,  and  separated  from  the  corpus  callosum 
by  a  narrow  furrow,  which,  from  its  surrounding  the  edge 
of  the  hemisphere  after  the  manner  of  a  hem,  is  called  the 
ourlet  or  hem-like  convolution ;  it  bends  down  in  front  with 
the  corpus  callosum,  and  is  lost  in  the  inferior  convolutions 
at  the  Sylvian  fissure,  behind;  it  also  follows  the  corpus  cal- 
losum, is  attached  to  the  posterior  convolutions,  and  can  be 
traced  downward  and  forward  into  the  middle  lobe  form- 
ing the  hippocampus  major. 

Another  large  primary  one  bounds  the  fissure  of  Sylvius, 
and  within  this  fissure  is  a  cluster  of  radiated  convolu- 
tions called  the  "  island  of  Eeil." 

The  fissure  of  Sylvius  is  made  a  very  important  point  by 
Mr.  Solly,  as  from  one  particular  spot  within  it,  called  the 
quadrilateral  spot  or  substantia  perforata  anterior,  all  the 
convolutions  are  made  to  arise.  At  this  spot  the  hemi- 
spherical ganglia  are  first  observed  as  a  mere  point,  and 
from  thence  they  gradually  expand  and  develop  themselves. 

Functions  of  the  Convolutions. — The  convolutions  are 
regarded  as  the  especial  ganglia  or  instruments  of  the 
mind,  and  comparative  anatomy,  experiments  on  living 
animals,  "developmental"  anatomy,  and  pathology  are  all 
brought  to  demonstrate  most  conclusively  that  the  convo- 
lutions constitute  the  especial  cerebral  organs  of  intel- 
lectual action — (for  further  remarks  see  nervous  tissue, 
under  the  head  of  Alphabet  of  Anatomy.)  The  cerebrum 
contains  a  variety  of  bodies,  which  we  will  examine  from 
the  base  or  below  upward,  as  this  is  found  to  be  the  natural 
order  of  development. 

The  Crura  Cerebri  (Fig.  16)  constitute  the  peduncles  of 
the  upper  brain,  and  are  situated  at  the  anterior  or  upper 
edge  of  the  pons.  They  are  two  in  number  and  consist  of 
white,  thick,  fibrous  cords  about  half  an  inch  in  length,  round 


412  CEREBRUM. 

at  the  pons,  but  becoming  more  transverse  as  they  ascend  to 
the  optic  thalami,  and  corpora  striata ;  here  they  become  en- 
larged and  flattened,  and  enter  these  latter  bodies.  As  they 
ascend  from  the  pons  they  diverge,  and  are  connected  by  the 
intercrural  lamina,  or  middle  perforated  plate.  The  optic 
tracts  pass  over  them  internally  and  in  front,  and  they  form 
the  floor  of  the  iter  a  tertio  ad  quartum  ventriculum.  Each 
crus  is  marked  by  a  groove  into  two  tracts,  one  of  which  is 
continuous  with  the  anterior  pyramidal  tract  through  the 
pons,  on  to  the  corpus  striatum — the  other,  which  is  the 
larger,  corresponds  to  the  olivary  body  and  goes  to  the  thal- 
amus.  On  cutting  the  crus  it  presents,  near  its  centre,  a 
mass  of  gray  matter  having  rather  a  darkish  appearance, 
and  called  locus  niger.  On  the  inner  surface  of  the  crura 
is  seen  the  attachment  of  the  third  pair  of  nerves.  The 
size  of  the  crura,  it  is  believed,  bears  a  proportion  to  that 
of  the  hemispheres  into  which  they  expand. 

The  Corpora  mammillaria,  or  albicantia,  (Fig.  16,)  are  two 
small  white  bodies,  about  the  size  of  a  pea,  situated  upon 
the  inner  surfaces  of  the  crura  at  their  anterior  extremity. 
Their  structure  is  white  externally,  and  gray  or  cineritious 
within.  Their  relation  is  with  the  anterior  pillars  of  the 
fornix  which  terminate  in  them.  They  have  the  tuber 
cinereum  in  front,  and  partly  assist  in  closing  the  third 
ventricle.  These  with  the  locus  niger,  are  regarded  as 
ganglionic. 

The  Tuber  Cinereum  (also  calle&pons  Tarini)  is  a  soft,  gray 
body,  on  the  under  surface  of  the  crura  cerebri,  in  front  of 
the  albicantia,  and  behind  the  optic  commissures.  It  forms 
the  floor  of  the  third  ventricle. 

The  Infundibulum  is  a  conical  tubular  body  of  gray  mat- 
ter, proceeding  from  the  centre  of  the  tuber  cinereum,  and 
descending  to  the  pituitary  gland  in  the  sella  turcica.  Its 
upper  part  opens  into  the  third  ventricle — its  lower  part 
forms  the  apex,  and  by  some  is  said  to  be  closed — though 
Meckel  asserts  it  is  open  through  its  whole  extent. 

The  Pituitary  gland  is  situated  in  the  sella  turcica  of  the 
sphenoid  bone,  between  the  dura  mater  and  tunica  arach- 


TUBERCULA  QUADRIGEMIXA.  413 

noidea,  by  which,  membranes  it  is  firmly  retained  in  its 
place,  and  has  a  very  slight  connection  with  the  brain.  It 
is  oval  transversely,  and  presents  the  appearance  of  two 
lobes,  of  which  the  anterior  is  the  larger.  It  is  a  firm  body 
consisting  of  cineritious  matter  externally,  and  medullary 
within.  On  either  side  a  depression  is  observed  connecting 
it,  by  two  small  canals,  with  the  infundibulum.  Though 
called  a  gland,  yet  there  is  nothing  in  its  structure  or  func- 
tion, so  far  as  we  are  acquainted,  by  which  it  can  be  placed 
among  the  glands. 

Tubercula  Quadrigemina. — Dissection. — Having  the  base 
of  the  brain  uppermost,  draw  the  cerebellum  forward  and 
remove  the  pia  ma-  FIG.  116. 

ter.  These  are  four 
beautifully  white 
bodies,  situated 
above  the  crura 
cerebri,  and  behind 
are  connected  with 
the  tlialami.  The 
superior  are  called 
the  nates ;  the  infe- 
rior, the  testes.  It 
is  the  nates  which  are  connected  with  the  thalami.  The 
testes  are  united  to  the  cerebellum  by  two  thin,  white  lam- 
inae, called  the  processus  a  cerebello  ad  testes,  which  diverge 
to  tfye  cerebellum,  through  and  forming  part  of  its  crus. 
Between  these  processes  is  seen  a  white  layer  of  medullary 
matter  extending  from  one  side  to  the  other,  forming  the 

FIG.  116  represents  a  longitudinal  section  of  .the  Brain,  the  incision  being 
made  along  the  middle  line  between  the  two  hemispheres  of  the  cerebrum. 
a  Inner  surface  of  the  left  hemisphere,  b  Section  of  the  cerebellum,  dis- 
playing the  arbor  vitae.  c  Medulla  oblongata.  d  Corpus  callosum.  e  Fornix. 
/  One  of  the  crura  of  the  fornix.  g  One  of  the  corpora  albicantia.  h  Septum 
lucidum.  i  Velum  interpositum.  j  Division  of  the  middle  commissure  of  the 
third  ventricle,  k  Division  of  anterior  commissure.  I  Division  of  posterior 
commissure,  m  Corpora  quadrigemina.  n  Pineal  gland,  o  Aqueduct  of 
Sylvius,  or  iter  a  tertio  ad  quartum  ventriculum.  p  Fourth  ventricle,  q  Pons 
Varolii.  r  Crus  cerebri  s  Tuber  cinereum.  t  One  of  the  optic  nerves,  u 
Left  olfactory  nerve. 


414  PINEAL  GLAND — THALAMI  OPTICI. 

roof  of  tlie  fourth  ventricle,  and  called  the  valve  of  Vieus- 
sens. 

This  valve  is  streaked  with  gray  matter — is  covered  by 
the  superior  vermiform  process,  and  has  the  fourth  pair  of 
nerves  arising  from  it.  A  tube  or  canal  is  traced  beneath 
the  tubercula  quadrigemina,  leading  from  the  third  to  the 
fourth  ventricle,  beneath  the  valve  of  Vieussens,  called  the 
aqueduct  of  Sylvius.  The  four  tubercles,  though  separated 
l^y  a  transverse  and  vertical  fissure,  have  but  one  common 
base.  They  are  covered  by  a  vascular  membrane — the 
velum  interpositum.  The  structure  of  these  bodies  is  white 
without,  and  gray  within. 

Only  two  of  these  tubercula  are  seen  in  fish  and  reptiles, 
and  are  viewed  as  the  optic  lobes,  or  the  organs  which  re- 
ceive and  recognize  the  impressions  of  light,  color,  &c. 

The  pineal  gland,  (Fig.  116,)  is  situated  upon  the  nates 
and  is  surrounded  by  the  velum  interpositum,  a  reflection 
of  pia  mater.  It  is  an  oblong,  reddish  body,  composed  of 
cineritious  matter,  and  containing  calcareous  particles  or 
gritty  matter  called  acervulus,  which  on  analysis  is  found 
to  consist  principally  of  phosphate  and  carbonate  of  lime. 
The  posterior  part  of  this  gland  is  soft  and  called  cona- 
rium.  It  is  united  to  the  thalami  by  two  delicate  processes, 
the  pedunculi,  which  proceed  forward  on  the  inner  mar- 
gins of  the  thalami,  and  join  the  descending  pillars  of 
the  fornix.  A  variety  of  opinions  have  been  indulged  in 
reference  to  the  use  of  this  gland.  Des  Cartes  believed  it 
to  be  the  seat  of  the  soul,  arid  Majendie  that  it  closed  the 
aqueduct  of  Sylvius,  and  thus  cut  off  the  communication 
between  the  third  and  fourth  ventricles,  while  another  and 
more  plausible  view  makes  it  a  commissural  body. 

Thalami  optici,  or  posterior  ganglia,  (Fig.  117.) — These 
ganglia  are  very  prominent  in  the  interior  of  the  brain. 
They  are  situated  upon  the  upper  surface  of  the  crura  cere- 
bri,  and  can  be  most  readily  got  at  by  separating  the 
hemispheres,  and  turning  aside  the  corpus  callosum  and 
fornix,  which  cover  them.  The  thalami  are  large,  oval 
bodies,  placed  side  by  side  in  the  longitudinal  direction, 


.  THALAMI-OPTICI. 


415 


about  an  inch  and  a  half  long,  and  three  quarters  of  an  inch 
in  breadth  and  depth.  They  are  convex  superiorly  and  in- 
ternally, and  form  the  floor  of  the  lateral  ventricles.  They 
are  separated  in  front  by  the  teenia  semi-circularis,  from 
the  corpora  striata,  and  are  connected  behind  to  the  tuber- 
cula  quadrigemina ;  on  the  posterior  and  inferior  free  por- 
tion two  rounded  eminences  are  observed,  of  a  grayish  color, 
called  corpus  geniculatum,  ex- 
ternum  and  internum.  The  op- 
tic nerves  are  connected  with 
these  eminences.  A  third  tu- 
bercle is  spoken  of,  situated 
above  the  corpora  geniculata, 
and  called  the  tuberculum  pos- 
ter ius  superius. 

The  structure  of  the  thalami 
is  medullary  without,  and  a 
mixture  of  white  and  gray  mat- 
ter within,  forming  a  plexi- 
form  arrangement.  The  fibres 
are  traced  to  the  olivary  or 
sentient  tract  with  which  they 
are  continuous,  also  to  the 
testes  by  the  processes  a  cere- 
bello  ad  testes,  and  to  the  posterior  and  upper  part  of  the 
crura  cerebri.  From  their  external  surface  these  fibres  ex- 
pand into  the  hemispheres.  On  their  internal  and  upper 
surface  is  seen  the  long  peduncle  of  the  pineal  gland,  and 
at  their  anterior  part  they  are  connected  to  the  descending 
crura  of  the  fornix,  to  the  tuber  cinereurn,  and  corpora 
albicantia. 

These  thalami  have  been  called,  as  stated,  the  great  pos- 

FIG.  117  represents  a  horizontal  section  of  the  brain.  /  Corpus  callosum. 
g  Raphe  in  its  centre,  h  Lines)  transversae.  i  Centrum  ovale  of  Vieussens. 
j  Cortical  portion  of  cerebrum,  fc  Medullary  portion  of  cerebrum.  I  Lateral 
ventricle,  m  n  o  Its  anterior,  middle,  and  posterior  cornua.  p  Corpus  stria- 
turn,  q  Thalami  nervi  optici.  r  Linea  semi-circularis.  s  Hippocampes  major. 
t  Pes  hippocampi,  u  Taenia  hippocampi,  v  Hippocampus  minor,  to  Plexus 
choroides. 


416  COEPORA-STRIATA. 

terior  cerebral  ganglia — are  considered  as  the  centres  of 
sensation,  and  have  been  observed  to  bear  a  proportion  in 
size  to  the  posterior  lobes  of  the  cerebrum.  Between  the 
thalami  a  cavity  is  noticed,  called  the  third  ventricle.  This 
cavity  has  the  fornix  above  and  in  front — the  tuber  ciner- 
eum  below,  and  the  tubercula  quadrigemina  behind.  At 
its  anterior  part  it  opens  into  the  infundibulum,  and  in  its 
posterior  portion  it  communicates  with  the  fourth  ventri- 
cle by  the  aqueduct  of  Sylvius. 

This  cavity  is  closed  by  a  soft  layer  of  cineritious  matter 
called  the  commissura  mollis,  which  connects  the  two  inter- 
nal surfaces  of  the  thalami  together. 

In  front  of  this  commissure  is  the  foramen  commune  an- 
terius,  leading  to  the  pituitary  gland ;  and  behind  is  the 
foramen  commune  posterius,  leading  to  the  fourth  ventricle. 
The  posterior  commissure  is  behind  the  third  ventricle,  and 
connects  the  thalami  at  this  point.  It  is  a  short,  white, 
round  cord,  extending  transversely.  There  is  another 
white,  round  cord,  called  the  anterior  commissure,  which 
belongs  more  properly  to  the  next  bodies  we  have  to  ex- 
amine. 

Corpora  Striata,  (Fig.  117.) — These  bodies,  so  called  from 
their  striated  appearance  when  cut  into,  are  also  named 
anterior  or  superior  ganglia  of  the  cerebrum.  Their  situa- 
tion is  in  front  of  the  thalami ;  their  shape  is  pyraform, 
having  their  smaller  ends  looking  backward  and  outward, 
and  enclosing  the  thalami — while  their  larger  extremities 
converge  and  touch  each  other  in  front.  They  are  about 
two  and  a  half  inches  long,  and  help  to  form  the  floor  of 
the  lateral  ventricles. 

Their  structure  is  soft,  vascular,  and  cineritious  on  their 
surface.  Internally  the  gray  matter  is  seen  intermixed 
with  the  white  medullary  strias,  or  fasciculi.  These  fasci- 
culi can.  be  traced  from  the  anterior  or  motor  portion  of 
each  crus,  and  still  further  back  from  the  anterior  rods 
of  the  spinal  cord ;  after  passing  through  the  corpora 
striata,  they  expand  principally  into  the  anterior  and 
middle  lobes  of  the  hemispheres,  to  which  they  bear  a 


LATERAL  VENTRICLES — FORNIX.  41 T 

relative  proportion.  They  are  regarded  as  the  ganglia,  or 
centres  of  motion,  seeing  their  fibres  come  mostly  from  the 
motor  tract. 

They  are  separated  from  the  thalami  by  the  tcenia  semi- 
circularis,  which  is  a  narrow  medullary  band,  dividing 
these  two  sets  of  ganglia  from  each  other,  and  extending 
from  the  corpus  geniculatum  externum,  upon  the  optic  thal- 
amus,  to  the  descending  crus  of  the  fornix.  Its  function  is 
considered  commissural. 

The  Lateral  Ventricles  (Fig.  11 7)  are  cavities  occupying 
the  centre  of  the  brain.  Each  of  them  has  three  cornua — 
the  anterior  passing  forward  in  the  anterior  lobe ;  the  mid- 
dle winding  downward,  forward,  and  outward  into  the 
middle  lobe;  and  the  third,  or  posterior,  passing  back  into 
the  posterior  lobe.  These  ventricles  are  large,  horizontal, 
but  very  irregular  cavities,  bounded  above  by  the  corpus 
callosum,  having  for  their  floor  the  corpora  striata,  thalami 
optici,  and  fornix ;  and  separated  from  each  other  by  the 
septum  lucidum. 

The  anterior  cornu  presents  nothing  of  any  great  import- 
ance, except  the  corpus  striatum,  already  noticed.  In  the 
middle  cornu  is  seen  the  hippocampus  major,  or  cornu  am- 
monis,  a  large,  winding,  and  beautifully  white  body — con- 
vex externally,  and  concave  internally.  It  follows  the 
whole  extent  of  this  cavity,  occupying  its  floor,  and  fermi- 
nates  in  some  tubercles  called  pes  hippocampi.  This  body  is 
the  continuation  of  the  primary  convolution,  called  "  ourlet" 
Its  internal  edge  is  loose  and  concave,  presenting  a  narrow 
white  band,  called  tcenia  hippocampi,  or  corpus  fiiribriatum. 
Beneath  the  taenia  a  narrow  cineritious  line  is  seen,  named 
from  its  serrated  appearance,  corpus  denticulatum  or  fascia 
dentata.  In  the  posterior  cornua  a  smaller  eminence  is  ob- 
served, the  hippocampus  minor,  white  externally  and  gray 
within. 

Fornix. — This  body,  (Fig.  116,)  so  called  from  its  arch  or 

vault-like  appearance,  is  triangular  in  its  shape  and  forms 

the  roof  of  the  third  ventricle.     It  is  situated  beneath  the 

corpus  callosum  and  septum  lucidum,  next  to  be  examined. 

27 


418  FOKNIX — VELUM  INTERPOSITUM. 

The  fornix  is  a  white,  medullary  body,  convex  above,  larger 
behind,  where  it  receives  three  roots  to  the  hippocampus 
major,  minor ,  and  tcenia  hippocampi.  The  union  of  these 
roots  constitutes  the  body  of  the  fornix,  which,  arching  over 
the  third  ventricle  and  resting  upon  the  thalami,  proceeds 
forward  to  terminate  in  two  white  cords  or  pillars  called 
the  anterior  crura  of  the  fornix.  These  descend,  adhering 
to  the  thalami  in  front,  and  terminating  in  the  corpora 
mammillaria,  or  albicantia.  The  upper  surface  of  the  fornix 
is  free  and  smooth ;  the  lower  presents  several  oblique  lines 
called  lyra,  or  corpus  psalloides.  Its  structure  is  medullary 
and  fibrous,  and  its  function  is  considered  commissural, 
forming  extensive  and  distinct  connections  with  different 
parts.  Its  posterior  crura  are  related  to  the  middle  and 
posterior  lobes  ;  its  body  is  connected  with  the  septum  lu- 
cidum,  and  corpus  callosum;  and  its  anterior  crura  join 
the  thalami,  the  peduncles  of  the  pineal  gland,  the  tcenia 
semicirculares ,  the  corpora  albicantia,  and  the  tuber  cine- 
reum. 

On  the  edges  of  the  fornix  is  seen  a  fold  of  membrane 
loaded  with  a  mass  of  blood-vessels — one  on  each  side,  and 
formed  of  a  reflection  of  pia  mater,  called  plexus  choroides. 
This  plexus  enters  the  middle  crura  at  the  great  central 
fissure  between  the  optic  thalami  and  tgenia  hippocampi ; 
it  is  seen  as  a  loose,  floating  body,  following  the  course  of 
the  hippocampus  major,  covering  the  thalami,  and  proceed- 
ing forward  to  the  anterior  crura  of  the  fornix.  Behind  the 
foramen  commune  anterius,  they  both  unite  to  form  the 
vein  of  Galen,  vena  Galeni,  which  runs  back  along  the  mid- 
dle of  the  velum  interpositum  to  the  straight  sinus. 

This  Velum  Interpositum  (Fig.  116)  is  situated  on  the 
under  surface  of  the  fornix.  It  consists  of  pia  mater,  and 
prevents  any  communication  between  the  third  and  lateral 
ventricles,  except  at  its  anterior  part,  where  is  seen  an 
opening,  called  the  foramen  of  Monro,  beneath  the  anterior 
crura  of  the  fornix.  This  membrane  goes  back  to  the 
pineal  gland,  and  so  envelops  it,  that  there  is  danger  of 
removing  this  gland  along  with  it,  unless  great  care  be 


CORPUS  CALLOSUM.  419 

taken.  At  this  point,  beneath  the  vein  of  Galen,  the  arach- 
noid canal,  or  canal  of  Bichat,  is  seen. 

Corpus  Callosum ,  (Figs.  116, 117.) — By  separating  widely 
the  hemispheres,  this  body  is  seen  presenting  a  brilliant 
white  appearance,  and  quadrilateral  shape.  It  occupies 
the  centre  of  the  brain ;  its  greatest  length,  which  is  about 
three  or  four  inches,  being  in  the  longitudinal  direction. 
It  forms  the  roof  of  the  lateral  ventricles,  and  covers  the 
for  nix.  Its  upper  surface  is  white,  convex,  and  marked 
with  two  or  three  longitudinal  lines  called  the  raphe,  from 
which  transverse  lines  are  seen  on  either  side.  Its  anterior 
portion  is  round  and  bends  downward  into  the  anterior 
lobes  and  base  of  the  brain.  Its  posterior  end  is  thick, 
round,  and  continuous  with  the  fornix  and  hippocampi; 
externally,  portions  of  it  curve  downwards  and  join  the 
thalami  and  corpora  striata.  The  corpus  callosum  con- 
nects the  two  hemispheres  of  the  cerebrum,  and  is  called 
the  great  cerebral  commissure. 

The  Septum  Lucidum  (Fig.  116)  is  the  membranous  par- 
tition between  the  lateral  ventricles,  and  extends  from  the 
median  surface  of  the  corpus  callosum  to  the  fornix.  It 
is  described  as  consisting  of  four  laminee.  The  first  comes 
from  the  lateral  ventricle ;  the  second  consists  of  gray  mat- 
ter ;  the  third  is  a  white,  fibrous  layer ;  and  the  fourth  is 
a  very  delicate  layer  containing  a  cavity  called  the  f/tli 
ventricle.  It  is  generally  regarded  as  being  composed  of 
two  laininse,  between  which  is  the  fifth  ventricle;  and 
each  of  these  is  capable  of  being  divided  into  two — the 
outer  layer  being  cineritious,  the  inner  medullary.  This 
ventricle,  in  the  natural  state,  is  supposed  to  be  closed;  but 
it  is  thought  by  others  to  form  a  portion  of  the  third  ven- 
tricle, as  in  the  early  periods  of  uterine  life.  Tiedenman 
found  it  to  communicate  with  the  latter  cavity.  The  func- 
tion of  the  septum  lucidum  is  regarded  as  commissural. 

On  making  a  horizontal  section  of  one  of  the  hemispheres 
of  the  cerebrum,  in  the  centre  there  is  observed  a  mass  of 
white,  fibrous,  medullary  matter,  surrounded  by  a  wavy 
line  of  gray.  This  central  appearance  is  called  the  centrum 


420  NERVES  OF  ENCEPHALON. 

cvale  minus.  The  other  hemisphere,  cut  in  the  same  way, 
presents  a  similar  view ;  and  the  two  together  receive  the 
name  of  centrum  ovale  majus,  which  is  nothing  more  than 
the  white  central  mass  of  medullary  matter,  surrounded 
by  gray  or  cineritious  substance.  (Fig.  11*7.) 

NERVES   OF   THE   ENCEPHALON.    (Fig.  16.) 

The  nerves  of  the  encephalon  are  nine  pair,  according  to 
the  old  nomenclature,  and  eleven  or  twelve  pair  according 
to  the  more  modern.  The  additional  number  is  arrived  at 
by  making  two  out  of  the  seventh  and  three  out  of  the 
eighth  pair. 

M.  Cruveilhier  remarks  it  is  more  philosophical  to  exam- 
ine the  nerves  of  the  brain  from  behind  forward,  but  as  it  is 
more  convenient  in  the  removal  of  the  brain,  to  study  these 
nerves  then,  we  shall  adopt  the  usual  plan,  and  describe 
them  from  before  backward,  and  in  their  numerical  order. 

First  Pair,  or  Olfactory  Nerves,  (Fig.  118.) — These  are  the 
nerves  of  smell,  and  are  situated  on  the  lower  surface  of 
the  anterior  lobes  of  the  cerebrum.  Each  arises  by  three 
filaments,  one  of  which  is  external  from  the  fissure  of  Syl- 
vius, long  and  white ;  the  second  internal  from  the  corpus 
callosum,  and  the  middle,  gray,  from  the  posterior  convolu- 
tion of  the  anterior  lobe.  The  three  unite  to  form  a  soft, 
gray,  triangular  nerve,  having  a  bulbous  expansion,  which 
is  lodged  between  the  convolutions,  where  it  is  protected 
and  covered  by  the  arachnoid  membrane.  Each  bulb  rests 
on  the  cribriform  plate  of  the  ethmoid  bone,  on  either  side  of 
the  crista-galli,  whence  proceed  numerous  filaments  through 
the  various  foramina  in  this  plate  to  the  mucous  membrane 
of  the  nose.  These  divide  into  two  sets,  an  internal,  and 
an  external,  the  former  going  to  the  septum,  the  latter  to  the 
upper  and  middle  spongy  bones.  These  nerves  differ  from 
all  others  in  their  shape,  which  is  triangular,  and  in  their 
structure,  which  is  very  soft,  some  fibres  being  white,  others 
gray,  and  in  not  being  surrounded  by  the  arachnoid.  Their 
bulbs  are  called  by  Mr.  Solly  the  olfactory  ganglia. 

Second  Pair,  or  Optic. — These  are  the  nerves  of  sight. 


NERVES   OF  ENCEPHALON. 


421 


(Fig.  118;)  they  are  large,  and  arise  from  the  nates  of  the 
tubereula  quadrigemina,  and  the  corpora  genlculata  externa, 
upon  the  optic  thalami.  From  these  origins,  on  either  side, 
is  formed  a  soft,  flat  band,  the  tractus  opticus,  which  winds 
round  the  crus  cerebri,  and  then  converges  to  meet  its  fel- 
low of  the  opposite  side  in  the  optic  commissure  or  chiasma 
before  the  sella  turcica ;  here  it  is  connected  by  filaments 
to  the  tuber  cinereum,  and  the  point  is  not  settled  whether 
these  nerves  at  this  junction  decussate  or  simply  unite,  or 
whether  both  conditions  exist.  The  latter  opinion  seems 
the  most  tenable,  that  one  portion  of  the  fibres  which 
compose  the  optic  nerves,  at  their  commissure,  cross  each 
other  and  go  to  the  opposite  eye,  while  the  other  portion 
simply  unites  with  its  fellow  and  then  passes  to  the  eye  of 
the  same  side.  Anterior  to  the  junction,  the  nerve  becomes 
round  and  passes  forward  on  F,G> 

the  inside  of  the  carotid,  and 
above  the  ophthalmic  artery 
to  the  optic  foramen  through 
which  it  passes.  On  enter- 
ing the  orbit  it  is  surrounded 
by  a  process  of  dura  mater? 
which  divides  into  two  por- 
tions, the  one  being  continu- 
ous with  the  periosteum  of 
the  orbit,  the  other  with  the 
sclerotic  coat  of  the  eye.  The 
nerve  then  enters  the  back 
part  of  the  eye  through  the 
sclerotic  and  choroid  coats 
to  terminate  in  the  retina. 

Third  Pair}  or  Motores  Oculorum,  (Figs.  118,  101,)  are 

FIG.  118  represents  the  second  pair  or  nerves  of  sight,  the  Optic.  1  1  Ball 
of  the  eye,  the  right  one  has  the  sclerotic  and  cervical  coats  removed  to  show 
the  retina.  2  Chiasm  of  optic  nerves.  3  Corpora  albicantia.  4  Infundibulum. 
5  Pons  Varolii.  6  Medulla  oblongata.  7  Third  pair  motores  oculi.  8  Fourth 
pair  pathetici.  9  Fifth  pair  trigemini.  10  Sixth  pair  motores  externi.  11 
Facial  and  auditory.  12  Eighth  pair  pneumogastric,  spinal  accessory,  and 
glosso-pharyngeal.  13  Ninth  pair  hypo-glossal. 


422  NERVES  OF  ENCEPHALON. 

nerves  of  motion,  and  arise  each  from  the  inner  side  of  the 
cms  cerebri,  close  to  the  pons,  its  fihres  heing  traced  to  the 
locus  niger  in  the  cms.  These  nerves  penetrate  the  dura 
mater  at  the  posterior  clinoid  process,  and  proceed  forward 
along  the  outer  wall  of  the  cavernous  sinus  to  the  foramen 
lacerum  superius,  through  which  they  pass,  and  then  di- 
viding into  two  branches,  supply  five  of  the  seven  muscles 
contained  in  the  orhit. 

Fourth  Pair  of  Nerves,  Pathetici  or  TrocMeares,  (Fig.  118.) 
These  are  the  smallest  nerves  of  the  brain,  not  larger  than 
an  ordinary  strand  of  cotton,  and  arise  each  by  two  or 
three  filaments  from  the  valve  of  Vieussens,  &nd.processus  a 
cerebello  ad  testem  ;  they  are  very  delicate  and  easily  broken, 
and  pursue  a  long  course  on  the  outer  margin  of  the  pons, 
between  the  cerebrum  and  cerebellum,  to  the  posterior  cli- 
noid process,  where  they  enter  a  canal  of  the  dura  mater, 
then  proceed  along  the  external  wall  of  the  cavernous  sinus, 
at  first  below  the  third,  then  above  all  the  nerves  at  this 
point,  to  the  foramen  lacerum  superius  or  sphenoidal  fissure, 
through  which  the  last  pass  to  be  distributed  solely  to  the 
superior  oblique  muscles  of  the  eye. 

Fifth  Pair,  Trifacial  or  Trigemini,  (Figs.  118,  T4.) — These 
are  compound  nerves,  having  filaments  both  of  sensation 
and  motion,  hence  they  have  been  called  the  cranial-spinal 
nerves.  They  are  the  largest  of  the  cerebral  nerves,  and, 
according  to  Dr.  Alcock,  arise  by  two  roots  from  an  emi- 
nence, on  a  longitudinal  tract  of  yellowish  matter  in  front 
of  the  floor  of  the  fourth  ventricle,  which  divides  inferiorly 
into  two  fasciculi,  traceable  downward  to  the  spinal  cord, 
the  one  going  to  the  anterior  column,  the  other  to  the  pos- 
terior. The  two  roots  having  this  origin,  emerge  on  the 
side  of  the  pons  Varolii,  where  it  is  continuous  with  the 
crus  cerebelli.  Here  they  are  separated  by  a  narrow,  trans- 
verse fasciculus.  The  union  of  the  two  constitutes  the  fifth 
nerve,  which  consists  of  from  TO  to  100  filaments  bound  to- 
gether by  pia  mater.  The  nerve  passes  forward  in  an  oval 
opening  or  canal  in  the  dura  mater,  formed  by  the  separa- 
tion of  the  two  layers  of  this  membrane,  and  then  expands 


NERVES  OF  ENCEPHALON.  423 

in  the  middle  fossa,  on  the  anterior  cerebral  surface  of  the 
petrous  bone,  into  the  Casserian  ganglion.  This  ganglion 
is  of  a  semilunar  shape,  and  presents,  on  removing  the  dura 
mater,  a  dark  and  flat  appearance,  with  its  filaments  mat- 
ted or  having  the  plexiform  arrangement.  On  raising  this 
ganglion,  the  smaller  motor  or  anterior  root  will  be  seen  to 
pass  on  its  under  surface  without  any  adhesion.  It  is  easily 
separated  and  may  be  traced  on  to  the  inferior  maxillary 
nerve,  with  which  it  unites. 

Three  large  branches  proceed  from  this  ganglion,  the  oph- 
thalmic, the  superior,  and  the  inferior  maxillary  nerves.  The 
first  enters  the  orbit  through  the  foramen  lacerum  superius, 
and  supplies  the  eye  and  its  appendages  with  common  feel- 
ing or  general  sensibility ;  the  second  or  superior  maxillary 
is  distributed  to  the  upper  jaw  and  face,  supplying  these 
parts  also  with  sentient  nerves  ;  the  third  or  inferior  maxil- 
lary nerve  is  the  largest  branch  and  passes  through  the  fora- 
men ovale.  Its  motor  portion  supplies  the  muscles  of  mas- 
tication, as  the  temporal,  masseter,  pterygoid,  and  buccina- 
tor, while  the  sensitive  goes  to  the  lower  jaw,  tongue,  chin, 
lips,  &c. 

Sixth  Prir,  Motor es  Externi  or  Abducentes  Oculi,  (Fig.  118.) 
This  pair  is  of  a  size  between  the  third  and  fourth.  Each 
nerve  arises  from  the  superior  extremity  of  the  corpus  pyra- 
midale,  close  to  the  pons,  passes  forward  to  the  body  of  the 
sphenoid  bone,  where  it  penetrates  the  dura  mater,  courses 
the  cavernous  sinus  on  the  outside  of  the  carotid,  enters  the 
orbit  through  the  foramen  lacerum  superius,  and  goes  to 
the  rectus  externus  muscle.  The  root  of  the  nerve  has  been 
traced  through  the  corpora  pyramidalia  into  the  gray 
matter  of  the  olivary  bodies. 

Seventh  Pair,  Portio  Dura  and  Portio  Mollis,  (Figs.  16, 
109.) — This  pair  is  regarded  by  some  as  two  distinct  nerves, 
and  so  divided.  The  portio  dura  is  the  smaller  of  the  two,  and 
arises  from  the  upper  part  of  the  medulla  oblongata  close  to 
the  lower  part  and  side  of  the  pons,  below  the  crus  cerebelli 
and  in  front  of  the  corpus  restiforme,  into  the  gray  neurine 
of  which  its  fibres  can  be  traced.  It  is  called  the  facial 


424  NERVES   OF   ENCEPHALON. 

nerve,  and,  according  to  Mr.  Bell,  lias  its  origin  from  the 
respiratory  tract.  It  enters  the  foramen  auditorium  inter- 
num,  passes  along  the  aqueduct  of  Fallopius,  and  emerges 
at  the  stylo-mastoid  foramen,  from  whence  it  is  distributed 
to  the  muscles  of  expression. 

The  portio  mollis,  or  auditory  nerve,  is  the  larger  of  the 
two,  and  the  most  posterior.  It  arises  from  the  side  of  the 
calamus  scriptorius,  the  floor  of  the  fourth  ventricle,  and  the 
corpus  restiforme,})y  several  filaments  which  form  a  very  soft, 
white  cord ;  then  unites  with  the  portio  dura,  and  enters 
along  with  it,  the  internal  auditory  foramen,  from  which, 
at  the  hase  of  this  canal,  it  separates  and  goes  to  supply 
the  internal  ear,  as  the  cochlea,  semicircular  canals,  &c. 
This  nerve  is  the  nerve  of  hearing. 

The  Eighth  Pair  consists  of  the  Glosso  Pliaryngeal,  (Figs. 
91,  118,)  Pneumogastric,  or  par  vagum,  and  the  Spinal 
accessory. 

The  glosso  pharyngeal  arises,  by  four  or  six  filaments, 
from  the  fissure  between  the  olivary  and  restiform  bodies, 
or  from  the  respiratory  tract;  these  unite  into  a  small 
nerve  which  joins  the  par  vagum.  The  par  vagum,  or  pneu- 
mogastric,  arises  below  the  last,  in  the  same  groove  between 
the  corpus  olivare  and  corpus  restiforme,  by  ten  or  fifteen 
filaments,  which,  uniting  together,  form  a  larger  nerve 
than  the  glosso-pharyngeal ;  the  two  now  proceed  together 
to  the  foramen  lacerum  posterius,  where  they  are  joined  by 
the  third  portion — the  spinal  accessory.  This  latter  nerve 
arises  low  in  the  neck — as  low  as  the  fourth  or  fifth  verte- 
bra, and  occasionally  as  low  as  the  seventh  cervical,  by 
several  filaments  from  the  respiratory  tract  on  the  sides 
of  the  medulla  spinalis,  between  the  roots  of  the  anterior 
and  posterior  spinal  nerves ;  it  ascends  behind  the  liga- 
mentum  denticulatum,  receiving  filaments  from  the  spinal 
nerves,  in  its  ascent,  and  after  entering  the  foramen  inag- 
nus,  proceeds  to  the  foramen  lacerum  posterius,  where  it 
joins  the  other  portions  of  the  eighth  pair.  They  all 
pass  through  the  foramen  lacerum  posterius,  anterior  to 
the  jugular  vein,  and  then  each  proceeds  to  its  peculiar 


BLOOD-VESSELS   OP  THE  BRAIN.  425 

place  of  distribution — the  glosso  pharyngeal  to  the  tongue 
and  pharynx,  the  pneumogastric  to  the  lungs  and  stomach, 
and  the  spinal  accessory  to  the  muscles  on  the  side  of  the  neck. 

The  several  portions  of  the  eighth  pair,  at  the  foramen 
lacerum  posterius,  have  each  a  distinct  sheath  of  dura  ma- 
ter; though  the  par  vagum  and  spinal  accessory,  having  heen 
seen  occupying  the  same  canal,  have  been  compared  to  a 
spinal  nerve,  the  latter  representing  the  anterior  or  motor 
root,  the  former  the  posterior  or  sentient. 

Ninth  Pair,  Lingual  or  Hypoglossal,  (Figs.  118, 9 1.) — These 
belong  to  the  tongue,  and  are  motor  nerves.  They  arise  by 
a  number  of  filaments,  which  vary  from  four  to  ten,  from 
between  the  corpus  pyramidaleand  olivare.  These  filaments 
unite  into  a  single  trunk,  one  for  each  side,  and  receiving 
a  sheath  of  the  dura  mater,  pass  through  the  anterior  con- 
dyloid  foramen  of  the  occipital  bone,  to  be  distributed  prin- 
cipally to  the  tongue. 

BLOOD-VESSELS  OF  THE  BRAIN. 

The  internal  carotid  and  vertebral  arteries  are  the  great 
sources  of  supply  of  blood  to  the  brain.  Each  internal  caro- 
tid gets  into  the  cavity  of  the  cranium,  by  a  tortuous  course 
through  the  carotid  canal  of  the  temporal  bone.  On  leav- 
ing this  canal  it  ascends  through  the  cavernous  sinus,  and 
at  the  anterior  clinoid  process  it  gives  off  the  ophthalmic 
artery  which  goes  to  the  eye  and  its  appendages.  At  this 
point  the  carotid  gives  off,  in  its  course,  small  branches  to 
the  cavernous  sinus  and  dura  mater.  The  remainder  of  its 
branches  supply  the  brain,  and  consist  of  the  anterior, 
middle,  and  posterior  cerebral. 

The  anterior  branch,  anterior  cerebri,  called  also  the  artery 
of  the  corpus  callosum,  proceeds  forward  and  inward,  and 
after  uniting  with  its  fellow  by  a  transverse  branch,  (the 
anterior  communicating  artery ,)  ascends  upon  the  upper  sur- 
face of  the  corpus  callosum,  supplying  this  body  and  the 
inner  surface  of  the  hemispheres.  The  middle  artery  is  the 
largest,  and  goes  outward  to  the  fissure  of  Sylvius,  supplying 
the  anterior  and  middle  lobes  of  the  cerebrum,  and  accend- 


426 


BLOOD-VESSELS  OF  THE  BRAIN. 


ing  upon  the  upper  surface  of  the  hemispheres  to  anasto- 
mose with  the  anterior  and  posterior  cerehral  arteries.  The 
posterior  branch  passes  hackward  to  join  the  posterior  cere- 
bral artery,  forming  the  side  of  the  circle  of  Willis,  and  is 
called  the  posterior  communicating  artery. 

FIG.  119.  The  internal  carotid 

sometimes  sends  off  a 
hranch  called  the  ar- 
teria  'choroidea,  which 
passes  into  the  mid- 
dle cornu  of  the  lat- 
eral ventricle,  and  is 
distributed  upon  the 
plexus  choroides. 

The  vertebral  arte- 
ries arise  from  the  sub- 
clavian,  sometimes 
from  the  aorta.  They 
ascend  in  a  straight 
line  through  the  series 
of  foramina  in  the 
transverse  processes  of 
the  six  upper  cervical 
vertebrae,  anterior  to 
the  cervical  nerves.  At 
the  second  vertebra  these  arteries  take  a  direction  outward, 
and  then  again  ascend  vertically  through  the  foramen  in 
the  transverse  process  of  the  atlas.  After  this  they  take  a 
horizontal  direction  backward,  round  the  superior  oblique 
process  of  the  atlas  in  a  depression  at  its  back  part,  and 
then  ascend  upward  and  inward  through  the  foramen 
magnum,  into  the  cranium,  penetrating  the  dura  mater  a 

FIG.  119  represents  the  Circle  of  Willis,  surrounding  the  Sella  Turcica. 
1  Vertebral  arteries.  2  The  two  anterior  spinal  branches,  forming  a  single 
trunk.  3  Posterior  spinal  artery.  4  Posterior  meningeal.  5  Inferior  cere- 
bellar.  6  Basilar  artery.  7  Superior  cerebellar  artery.  8  Posterior  cere- 
bral. 9  Posterior  communicating  branch  of  internal  carotid.  10  Internal 
carotid.  11  Ophthalmic  artery.  12  Middle  and  cerebral  artery.  13  Anterior 
cerebral  arteries.  14  Anterior  communicating  artery. 


BLOOD-VESSEIS  OF  THE  BRAIN.  427 

little  above  the  condyles  of  the  occipital  bone.  In  the 
cranium  they  are  seen  on  the  under  surface  of  the  medulla 
oblongata,  approaching  each  other  till  they  reach  the  pos- 
terior part  of  the  pons.  At  this  point  they  unite  into  a 
common  trunk  called  the  basilar  artery. 

The  vertebral  arteries  in  their  course  send  off  small  ar- 
teries to  the  membranes  of  the  spinal  marrow  and  adjacent 
muscles,  and  at  their  superior  extremity  they  give  off  three 
important  branches,  the  anterior  and  posterior  spinal,  and 
inferior  cerebellar  arteries.  The  anterior  and  posterior 
spinal,  as  elsewhere  stated,  are  two  long  and  delicate 
branches,  the  one  in  front,  the  other  behind  the  spinal 
cord,  running  the  entire  length  of  this  organ  and  giving 
off  branches  to  the  several  spinal  nerves. 

The  basilar  artery,  formed  by  the  junction  of  the  two 
vertebrals,  is  situated  on  the  median  line  of  the  pons,  send- 
ing many  fine  branches  into  its  substance,  and  at  its  upper 
edge  giving  off  four  branches,  two  to  each  side,  the  superior 
cerebellar  and  posterior  cerebral  arteries.  The  former  wind 
round  the  crura  cerebri,  send  a  branch  with  the  seventh 
pair  of  nerves  into  the  internal  auditory  foramen  and 
finally  distribute  themselves  upon  the  upper  surface  of  the 
cerebellum,  anastomosing  with  the  inferior  cerebellar  arte- 
ries. 

The  posterior  cerebral  are  much  larger  branches,  and 
separated  from  the  latter  at  their  origin  by  the  third  pair 
of  nerves.  They  receive  the  posterior  communicating  branch 
of  the  carotids,  wind  round  the  crura  cerebri,  to  which 
branches  are  supplied,  and  are  finally  spent  upon  the  pos- 
terior lobes,  anastomosing  with  the  middle  and  anterior 
arteries  of  the  cerebrum. 

The  circle  of  Willis  will  now  be  understood  to  be  formed 
in  front  and  laterally  by  the  internal  carotids  and  their 
posterior  communicating  branches,  while  the  back  part  of 
the  circle  comes  from  the  basilar.  This  circle  surrounds 
the  commissure  of  the  optic  nerve. 

The  veins  of  the  brain  have  already  been  noticed  with  the 
sinuses  of  the  dura  mater. 


428 


BLOOD-VESSELS  OF  THE  HEAD. 


SECTION    IV. 

% 
BLOOD-VESSELS  OF  THE  HEAD  IN  THEIR   NUMERICAL   ORDER. 

The  external  and  internal  carotid,  and  vertebral  arteries, 
are  the  great  sources  which  supply  the  head  with  blood. 

FIG.  120.  The  external  and  in- 

ternal carotids  arise  from 
the  common  carotids  in 
the  neck,  opposite  to  the 
space  between  the  os-hy- 
oides  and  the  thyroid 
cartilage.  The  external 
carotid  ascends  from  this 
origin  to  the  neck  of  the 
lower  jaw,adjacent  to  the 
meatus  auditorius  exter- 
nus.  It  is  crossed  near  its 
origin  by  the  lingual 
nerve;  also  by  the  di- 
gastric and  stylo-hyoid 
muscles,  and  is  covered  in 
front  by  the  platysma, 
and  superficial  fascia. 
Its  upper  extremity  is  imbedded  in  the  substance  of  the 
parotid  gland.  It  gives  off  the  following  branches  : 


SUPERIOR   THYROID. 
LINGUAL. 

Hyoid. 

Dorsalis  linguae. 
Sublingual. 

Ranine,  which  is  the  continued  trunk 
of  lingual. 


FACIAL. 

Inferior  palatine. 
Submaxillary. 
Sub-mental. 
Inferior  labial. 
Inferior  coronary. 
Superior  coronary. 


FIG.  120  represents  the  branches  of  the  External  Corotid  Artery,  a  Arte- 
ria-innominata.  6  Common  carotid,  c  Bifurcation  of  common  carotid,  d 
External  carotid,  e  Internal  carotid  artery.  /  Superior  thyroid,  g-  Lingual. 
h  i  Facial,  j  Submental.  fc  Continuation  of  facial.  I  m  Inferior  and  supe- 
rior coronary  arteries,  n  Nasal  or  angular  branch,  o  External  carotid  con- 
tinued, p  Internal  maxillary,  q  Temporal,  r  Posterior  auricular,  s  Occip- 
ital arjery. 


BLOOD-VESSELS   OP  THE  HEAD. 


429 


INTERNAL  MAXILLARY,  (Fig.  121.) 

Tympanic  branch. 

Greater  or  middle  meningeal. 

Less  meningeal. 

Inferior  dental,  or  maxillary. 

Posterior  deep  temporal. 

Masseteric* 

Pterygoid. 

Buccal. 

Anterior  deep  temporal. 

Superior  dental,  or  alveolar. 

Inferior  orbitar. 

Superior  palatine. 

Superior  pharyngeal. 

Spheno-palatine. 


Lateralis  nasi. 

Angularis,  or  terminating  branch. 

INFERIOR  OR  ASCENDING  PHARYNGEAL. 

Pharyngeal  branches. 
Posterior  meningeal. 

OCCIPITAL. 
Inferior  meningeal. 
Princeps  cervicis. 

POSTERIOR    AURICULAR. 

Stylo-mastoid. 

TEMPORAL. 

Anterior  auricular. 
Transverse  facial. 
Middle  temporal. 
Anterior  temporal. 
Posterior  temporal. 

The  superior  thyroid  is  the  first  branch  of  the  external 
carotid,  and  descends  to  be  distributed  principally  to  the 
FIG.  121.  thyroid  gland.     As  it  is  con- 

nected with  the  neck,  we  defer 
any  further  notice  of  it  till 
that  part  of  the  body  comes 
under  examination. 

The  lingual  artery  arises  just 
above  the  latter,  and  passes 
inward  above  the  os-hyoides 
to  the  base  of  the  tongue.  It 
is  covered  at  its  origin  by 
the  digastric  and  stylo-liyoid 
muscles,  and  at  the  base  of  the 
tongue  lies  between  the  hyo-glossi  and  genio-hyo-glossi, 
whence  it  runs  forward  to  the  tip. 

FIG.  121  represents  the  branches  of  the  Internal  Maxillary  Artery.  1  Ex- 
ternal carotid.  2  Trunk  of  transverse  facial.  3  4  Terminal  branches  of 
external  carotid.  3  The  temporal.  4  Internal  maxillary  artery— the  first 
part  of  its  course  extending  to  the  first  arrow.  5  Pterygoid,  or  second  part  of 
its  course  between  the  two  arrows.  6  Pterygo  maxillary,  or  terminating  por- 
tion. The  branches  belonging  to  these  three  divisions  are,  7  A  tympanic 
branch.  8  Greater  meningeal.  9  Lesser  meningeal.  10  Inferior  dental.  Th 
second  division  are  muscular  branches,  as  the  temporal,  masseteric,  pterygoid 
and  buccal.  11  Superior  dental.  12  Infra  orbital.  13  Posterior  palatine. 
14  Spheno  palatine,  or  nasal.  15  Pterygo  palatine.  16  Pterygoid,  or  Vidian. 


430  BLOOD-VESSELS  OF  THE  HEAD. 

The  liyoid  is  the  first  branch  and  supplies  the  parts  above 
the  os-hyoides. 

The  dorsalis  linguce,  the  second  branch,  ascends  to  the 
dorsum  of  the  tongue  supplying  the  base  of  this  organ,  the 
fauces  and  the  velum. 

The  sublingual  is  the  third  branch,  and  sends  branches 
to  the  sublingual  gland,  the  inylo-hyoid  muscle,  and  the 
mucous  membrane ;  this  sometimes  comes  from  the  facial. 

The  canine  forms  the  continued  trunk  of  the  lingual,  and 
advances  forward  between  the  genio  hyo-glossus  and  lin- 
gualisj  to  the  tip  of  the  tongue,  sending  oif  branches  on 
either  side  as  it  proceeds  forward. 

The  facial  artery  arises  a  few  lines  above  the  lingual, 
opposite  the  os-hyoides,  ascends  behind  the  digastric  mus- 
cle to  the  base  of  the  lower-jaw,  a  little  anterior  to  its  angle, 
above  and  closely  connected  with  the  sub-maxillary  gland. 
It  mounts  over  the  lower  jaw  anterior  to  the  masseter  mus- 
cle, then  ascends  to  the  angle  of  the  mouth,  and  still  upward 
to  the  angle  of  the  eye,  where  it  terminates  by  anastomosing 
with  the  ophthalmic  branch  of  the  internal  carotid. 

Its  branches  are : 

The  inferior  palatine  which  ascends  by  the  side  of  the 
pharynx,  between  the  stylo-glossus  and  stylo-pharyngeus 
muscles,  to  supply  the  tonsils  and  velum,  and  anastomoses 
with  the  superior  palatine  from  the  internal  maxillary. 

The  submaxillary  sends  off  several  branches  to  the  sub- 
maxillary  and  adjacent  lymphatic  glands. 

The  sub-mental  comes  oif  at  the  base  of  the  lower  jaw  and 
proceeds  forward  upon  the  mylo-hyoid  muscle,  above  the 
anterior  belly  of  the  digastric  to  the  chin,  supplying  these 
muscles  and  anastomosing  with  its  fellow  of  the  opposite 
side,  and  with  the  inferior  dental  and  inferior  labial  arte- 
ries. 

The  next  branch  is  the  inferior  labial,  given  off  after  the 
facial  has  made  its  curve  upon  the  face.  This  supplies  the 
muscles  and  integuments  of  the  lower  lip. 

At  the  angle  of  the  mouth  is  the  inferior  coronary.  This 
sometimes  supplies  the  place  of  the  inferior  labial. 


BLOOD-VESSELS  OF  THE  HEAD.  431 

A  little  higher  is  the  superior  coronary.  Both  these 
course  along  the  margins  of  the  lips,  close  to  the  mucous 
membrane,  sending  many  branches  to  the  substance  of  the 
lips,  and  forming  by  anastomosis  with  their  fellows  of  the 
opposite  sides,  a  complete  circle  round  the  mouth. 

The  lateralis  nasi  is  the  next  in  order,  supplying  the  side 
and  dorsum  of  the  nose ;  while  the  angularis  is  the  termi- 
nating branch  of  the  facial,  anastomosing  with  the  nasal 
branches  of  the  ophthalmic.  This  artery  in  its  ascent  is 
connected  by  anastomosis  with  the  lingual,  the  inferior 
dental  as  it  escapes  from  the  anterior  mental  foramen,  the 
transverse  facial  and  inferior  orbitar  arteries. 

The  inferior  or  ascending  pliaryngeal  artery  is  one  of  the 
smallest  branches  of  the  external  carotid,  and  varies  in  its 
origin.  It  mostly  arises  opposite  to  the  lingual,  sometimes 
higher  up,  and  occasionally  springs  from  one  of  the  other 
branches.  It  ascends  on  the  side  of  the  pharynx,  covered 
by  the  stylo-pharyngeus,  to  the  base  of  the  skull,  where  it 
divides  into  its  two  principal  branches,  the  pliaryngeal  sup- 
plying the  pharynx,  tonsils,  palate,  and  Eustachian  tube, 
and  the  posterior  meningeal  passing  through  the  foramen 
lacerum  posterius,  and  distributed  upon  the  dura  mater  at 
the  base  of  the  brain. 

The  occipital  artery  arises  opposite  the  facial,  proceeds 
backward  behind  the  digastric,  the  sterno-mastoid,  and 
trachelo-mastoid  muscles  along  the  groove  within  the  mas- 
toid  process,  and  then  ascends  upon  the  occiput  between 
the  complexus  and  splenius  muscles,  anastomosing  with  its 
fellow,  the  posterior  auricular,  and  the  temporal  arteries. 

Its  principal  branches  are  muscular,  supplying  the  mus- 
cles just  mentioned  ;  the  inferior  meningeal,  which  ascends 
through  the  foramen  lacerum  posterius,  to  the  dura  mater, 
and  the  princeps  cervicis,  which  is  a  large  branch  and  may 
be  regarded  as  the  continued  trunk  of  the  occipital.  It  de- 
scends to  the  deep  muscles  of  the  neck,  and  anastomoses 
with  the  profunda  cervicis  of  the  subclavian,  thus  preserv- 
ing the  circulation,  when  the  common  carotid  is  ligated. 
Posterior  auricular  artery  is  a  small  branch,  and  arises  a 


432  BLOOD-VESSELS  OF  THE  HEAD. 

little  above  the  occipital,  not  Tinfrequently  in  common  with 
it ;  it  ascends  behind  the  parotid  gland,  between  the  mas- 
toid  process  and  the  meatus  auditorius,  supplying  the  in- 
teguments of  the  posterior  ear  and  scalp.  Some  of  the 
branches  are  seen  to  pass  through  the  pinna  to  the  anterior 
surface  of  the  ear.  Its  only  branch  having  a  name,  is  the 
stylo-mastoid.  This  enters  the  stylo-mastoid  foramen,  and 
distributes  branches  upon  the  aqueduct  of  Fallopius  and 
the  tympanum. 

The  temporal  artery  (Fig.  120)  is  one  of  the  terminating 
branches  of  the  external  carotid.  It  ascends  through  the 
substance  of  the  parotid  gland,  over  the  root  of  the  zygoma, 
in  front  of  the  meatus  auditorius,  about  an  inch  and  a  half 
above  the  zygomatic  arch,  where  it  terminates  by  dividing 
into  an  anterior  and  posterior  branch.  Its  branches  are 
the  anterior  auricular  to  the  anterior  part  of  the  pinna. 
The  transverse  facial  passes  horizontally  upon  the  face 
below  the  duct  of  Steno,  crossing  the  masseter  muscle  to  be 
distributed  to  the  adjacent  muscles  and  integuments,  and 
anastomosing  with  the  facial  and  infra-orbitar  arteries. 
This  artery  often  arises  from  the  external  carotid.  The 
middle  temporal  passes  through  the  temporal  fascia  and 
supplies  the  temporal  muscle.  The  anterior  temporal,  one 
of  the  terminating  branches,  goes  forward  to  the  os-frontis, 
supplying  the  muscles  and  integuments  in  this  region  and 
anastomosing  with  its  fellow  of  the  opposite  side,  and  with 
the  supra  orbital  arteries.  The  posterior  temporal,  the  other 
terminating  branch,  proceeds  backward  and  upward,  anas-' 
tomosing  with  the  posterior  auricular  and  occipital  arteries. 

The  internal  maxillary  artery  (Fig.  121)  is  the  remaining 
terminal  branch  of  the  external  carotid.  It  is  the  great 
artery  supplying  the  mouth  and  the  whole  of  the  dental 
apparatus. 

Dissection. — Saw  the  zygomatic  arch  through  at  both 
ends,  and  turn  it  down  with  the  masseter  muscle ;  divide 
the  tendon  of  the  temporal  muscle  from  its  insertion 
into  the  coronoid  process ;  divide  the  rarnus  about  its  cen- 
tre and  disarticulate.  Eemove  the  jaw  with  the  external 


BLOOD-VESSELS  OP  THE  HEAD.  433 

pterygoid  muscle,  when  this  artery,  with  the  deep  branches 
of  the  inferior  maxillary  nerve,  will  be  exposed. 

This  artery  commences  in  the  substance  of  the  parotid 
gland,  opposite  the  meatus  auditorius  externus ;  passes 
horizontally  inward  behind  the  neck  of  the  lower  jaw, 
between  it  and  the  internal  lateral  ligament,  and  between 
the  inferior  dental  and  gustatory  nerves,  to  the  space  be- 
tween the  pterygoid  muscles ;  at  this  point  it  passes  either 
between  these  muscles,  or  winds  over  the  pterygoideus 
externus,  describing  a  tortuous  course  forward,  inward,  and 
somewhat  upward  to  the  tuberosity  of  the  superior  maxil- 
lary bone,  upon  which  it  makes  a  considerable  curve,  and 
then  dips  down  into  the  pterygo-maxillary  fossa,  where  it 
terminates.  Its  branches  are  as  follow : 

A  tympanic  branch,  which  passes  through  the  glenoid 
fissure  to  the  tympanum,  and  also  supplies  the  temporo- 
maxillary  articulation.  The  greater  meningeal}  or  middle 
artery  of  the  dura  mater,  coming  off  behind  the  neck  of  the 
lower  jaw,  ascends  to  the  foramen  spinale  of  the  sphenoid 
bone,  through  which  it  passes  into  the  cranium,  and  there 
divides  into  an  anterior  and  a  posterior  branch,  which 
diverge  and  occupy  the  grooves  on  the  internal  surface  of  the 
parietal  and  temporal  bones,  supplying  the  dura  mater  and 
the  anterior  cranial  bones.  The  lesser  meningeal  passes 
through  the  foramen  ovale  to  the  dura  mater,  and  is  often  a 
branch  of  the  greater.  The  inferior  dental  or  maxillary,  as 
has  already  been  described,  arises  opposite  the  greater  me- 
ningeal behind  the  neck,  and  descends  between  the  bone  and 
internal  lateral  ligament  to  the  posterior  dental  foramen, 
which  it  enters  along  with  the  inferior  dental  nerve;  it 
then  follows  the  course  of  the  canal  beneath  the  roots  of 
the  teetYij  into  &at\  of  which  it  sends  successively  a  small 
branch,  till,  arriving  opposite  the  bicuspid,  it  divides  into 
two  branches,  one  of  which  comes  out  at  the  anterior  men- 
tal foramen  to  supply  the  chin,  and  anastomose  with  the 
facial ;  while  the  other  is  the  continued  trunk  going  for- 
ward as  far  as  the  symphysis,  and  supplying  the  canine 
and  incisor  teeth. 
28 


434  BLOOD-VESSELS  OF  THE  HEAD. 

The  posterior  deep  temporal  arises  next  in  order;  it  is  con- 
cealed by  the  external  pterygoid  and  temporal  muscle,  and 
is  distributed  to  this  latter  muscle. 

The  pterygoid  arteries  come  next ;  they  vary  ip  number 
and  size,  and,  as  their  name  implies,  supply  the  pterygoid 
muscles. 

The  masseteric  and  the  buccal  go  to  the  masseter  and 
buccinator  muscles,  and  also  give  branches  to  the  lining 
membrane  of  the  mouth.  The  buccal  sometimes  comes 
from  the  superior  dental,  or  the  next  branch  in  order. 

The  anterior  deep  temporal,  which  comes  off  just  before 
the  internal  maxillary,  enters  the  pterygo-maxillary  fossa, 
and  ascends  to  be  distributed  upon  the  temporal  muscle, 
anastomosing  with  the  posterior  and  middle  deep  temporal. 

The  superior  dental  or  alveolar  comes  off  next,  and  has 
been  stated,  in  noticing  the  vessels  supplying  the  teeth,  to 
wind  round  the  tuberosity  of  the  superior  maxillary  bone, 
sending  branches  through  the  posterior  dental  canals,  to 
the  molar  teeth,  and  to  the  lining  membrane  of  the  an- 
trum ;  it  then  proceeds  forward  along  the  alveoli,  supply- 
ing them  and  the  gums. 

The  inferior  orbital  arises  at  the  upper  part  of  the  pterygo 
maxillary  fossa,  and  after  sending  a  few  branches  into  the 
orbit,  through  the  spheno-maxillary  fissure,  it  enters  the 
infra  orbitar  canal,  in  company  with  the  infra  orbitar 
nerve,  and  on  arriving  near  the  anterior  orifice  of  this 
canal,  it  sends  downward  a  branch  to  supply  the  incisor 
and  canine  teeth,  and  lining  membrane  of  the  antrum. 
It  finally  emerges  at  the  infra  orbitar  foramen,  anasto- 
mosing with  the  ophthalmic  and  facial  arteries. 

The  superior  palatine  also  comes  off  in  the  pterygo-max- 
illary fossa,  and  descends  to  the  posterior  palatine  canal, 
distributing  branches  to  the  soft  palate;  it  then  curves 
forward,  in  a  groove,  upon  the  hard  palate,  internal  to  the 
alveoli,  giving  off  ramifications  to  the  lining  membrane  of 
the  roof  of  the  mouth,  and  proceeds  to  the  foramen  iu- 
cisivum,  to  anastomose  with  the  spheno-palatine  or  nasal 
artery. 


BLOOD-VESSELS   OF  THE  HEAD. 


435 


The  superior  pharyngeal,  m  ptery go-palatine,  is  sometimes 
a  branch  of  the  latter,  and  supplies  the  upper  part  of  the 
pharynx  and  Eustachian  tube.  The  spheno-palatine,  or 
nasal,  is  the  terminating  trunk  of  the  internal  maxillary, 
and  passes  along  with  the  nerve  of  the  same  name,  through 
the  spheno-palatine  foramen,  into  the  nose,  where  it  divides 
into  two  branches — one  going  to  the  septum,  the  other  to 
the  middle  and  lower  turbinated  bones,  and  their  mucous 
membrane. 


BRANCHES    OF    INTERNAL    CAROTID 
ARTERY.    (Fig.    119.) 

Tympanic  branch. 
Anterior  meningeal. 
Ophthalmic — its  branches, 

Lachrymal. 

Central  artery  of  the  retina. 

Supra-orbital. 

Short  ciliary. 

Long  ciliary. 

Muscular. 

Posterior  ethmoidal. 

Anterior  ethmoidal. 

Palpebral. 


Nasal. 

Frontal. 

Anterior  cerebral. 

Middle  cerebral. 

Posterior  communicating. 

Choroidean. 

BRANCHES    OF    TERTEBRAL    ARTERY. 

Posterior  spinal. 
Anterior  spinal. 
Inferior  cerebellar. 
Basilar — formed  by  junction  of  two 
vertebral.     Its  branches  are, 

Superior  cerebellar. 

Posterior  cerebral. 


All  these  vessels  have  been  described  under  the  respect- 
ive heads  of  Blood-vessels  of  the  Brain  and  Eye,  which  see. 
The  veins,  corresponding  to  the  branches  of  the  external 
carotid,  have  both  a  similar  course  and  name,  so  that  a 
repetition  would  be  unnecessary  here. 


SECTION   IV. 
TABLE  OF  MUSCLES  OF  THE  HEAD. 

According  to  the  arrangement  of  Mr.  Harrison,  these 
muscles  are  classed  in  accordance  with  the  part  upon  which 
they  chiefly  act.  Six  classes  are  made,  embracing  thirty- 
six  pair,  and  two  single  muscles. 


FIRST  CLASS — one  muscle, 
The  muscle  of  the  Scalp,  or  Occipito- 
Frontalis. 


SECOND  CLASS — eleven  muscles, 
Those  of  the  Ear,  which  are  arranged 
iuto  three  groups. 


436 


MUSCLES  OF  THE  HEAD. 


First  Group — three  muscles  : 
Superior  auris,  or  Attollens  aurem. 
Anterior  auris,  or  Attrahens  aurem. 
Posterior  auris,  or  Retrahens  aurem. 

Second  Group— Jive  muscles  : 
Tragicus. 
Antitragicus. 
Helicis  major. 
Helicis  minor. 
Transversalis  auris. 

Third  Group — three  muscles  : 

Stapedius. 
Tensor  tympani. 
Laxator  tympani. 

THIRD  CLASS — eleven  muscles, 

Those  of  the  Eye  and  Appendages,  are 
arranged  in  two  groups — one  of  which 
acts  on  the  appendages,  the  other  on 
the  ball  of  the  eye. 

First  Group— five  muscles  r 
Occipito-Frontalis  —  its  palpebral  in- 
sertion. 

Corrugator  supercilii. 
Levator  palpebrse  superioris. 
Orbicularis  palpebrarum. 
Tensor  tarsi. 

Second  Group — six  muscles  : 
Rectus  superior,  or  Levator  oculi. 
Rectus  inferior,  or  Depressor  oculi. 
Rectus  internus,  or  Adductor  oculi. 
Rectus  externus,  or  Abductor  oculi. 
Obliquus  superior. 
Obliquus  inferior. 

FOURTH  CLASS— /our  muscles, 
Those   of  the  Nose,  arranged  in  two 
groups  : 


First  Group — proper  to  the  Nose: 

Pyramidalis  nasi. 
Compressor  nasi. 

Second   Group — common  to  the  Nose 
and  upper  Lip  : 

Levator  labii  superioris  alseque  nasi. 
Depressor  labii  superioris  alseque  nasi. 

FIFTH  CLASS — ten  muscles, 
Those  of  the  Mouth,  arranged  in  four 
groups : 

First   Group — one  muscle  : 
Orbicularis  oris. 

Second  Group — two  muscles  common  to 
the  upper  Lip  and  Nose  : 

Levator  labii  superioris  alaeque  nasi. 
Depressor  labii  superioris  alseque  nasi. 

Third  Group — two  muscles  : 

Levator  labii  inferioris. 
Depressor  labii  inferioris. 

Fourth  Group— Jive  muscles  : 

Levator  anguli  oris. 
Depressor  anguli  oris. 
Zygomaticus  major. 
Zygomaticus  minor. 
Buccinator. 

SIXTH  CLASS — muscles  of  mastication, 

Which  act  on  the  lower  jaw,  and  are 
four  pair : 

Masseter. 
.Temporal. 

Pterygoideus  externus. 
Pterygoideus  internus. 


RELATIONS   OP  THE  MOUTH  WITH  THE  HEAD.  43 T 

CHAPTER  VI. 

ANATOMICAL   AND   PHYSIOLOGICAL  RELATIONS  OF  THE  MOUTH 
WITH  THE  DIFFERENT  PARTS  OF  THE  HEAD. 

THE  mouth,  from  the  detailed  description  already  given, 
it  will  be  perceived,  is  a  very  complex  apparatus,  com- 
prising organs  of  the  greatest  variety,  in  form,  size,  deli- 
cacy and  adaptation,  and  embodying  functions  equally 
various  and  useful,  as  seen  in  the  multitude  of  duties  they 
perform,  their  surprising  promptitude  and  harmony  of 
action,  and  their  universal  sympathy  and  relation  with  all 
the  various  parts  composing  the  head ;  and  we  may  add 
the  rest  of  the  body  likewise,  as  we  shall  have  to  show  in 
the  proper  place.  So  close  and  so  essential  is  this  mutual 
relation  of  the  mouth  and  head,  that  they  cannot  exist 
separately. 

It  is  only  necessary  here  to  make  a  very  general  enu- 
meration of  these  relations  with  the  mouth,  so  as  to  impress 
especially  upon  the  dental  student  their  magnitude  and 
importance. 

The  mouth,  it  will  be  recollected,  consists  of  the  anatomi- 
cal elements  of  bone,  muscle,  blood-vessel,  nerve,  gland,  cellu- 
lar, mucous  and  adipose  structure;  which,  variously  combined, 
constitute  the  upper  and  lower  jaw,  the  teeth,  the  gums, 
the  tongue,  the  palate,  the  tonsils,  the  cheeks,  &c.,  in  a 
word,  all  the  parts  forming  the  walls  of  the  cavity  of  the 
mouth,  as  well  as  the  various  organs  contained  within  it. 
Now  each  one  of  these  elements,  and  of  the  several  organs 
they  form,  has  a  relation  more  or  less  direct  and  intimate 
with  the  other  portions  of  the  head. 

The  upper  jaw-bone  is  connected  to  a  number  of  the  bones 
of  the  cranium  and  face,  thereby  forming  one  continuous 
whole,  containing  numerous  cavities  of  various  sizes  and 
uses,  as  the  cavity  of  the  cranium  for  lodging  the  brain ; 
the  orbital  and  nasal  cavities,  the  maxillary  sinus,  &c.  The 
loiverjaw,  by  its  articulation  with  the  temporal  bones,  pre- 
sents a  fulcrum  and  lever,  which,  in  connection  with  the 


438      RELATIONS  OF  THE  MOUTH  WITH  THE  HEAD. 

various  muscles  attached  to  it  and  the  head,  is  in  its  power, 
strength,  beauty  and  mechanical  contrivance,  incomparably 
superior  to  any  thing  in  human  mechanics.  The  teeth  have 
not  only  a  direct  connection  with  the  jaws,  but  by  means  of 
their  blood-vessels  and  nerves,  they  have  nearly  as  direct 
and  close  a  relation  with  the  brain  and  its  membranes,  the 
eye,  the  ear,  and  the  nose.  The  fifth  pair  of  nerves  come 
from  the  brain  and  send  branches  to  the  teeth,  jaws,  eyes, 
nose,  ears,  &c.,  endowing  the  whole  with  sensibility  to  pain, 
and  so  close  is  this  sympathy  manifested  between  the  teeth 
and  brain,  that  the  simple  act  of  teething  frequently  occa- 
sions the  most  frightful  convulsions ;  while  cases  are  not 
wanting  to  show  that  irritation  of  this  same  set  of  nerves, 
from  decayed  teeth,  has  been  the  cause  of  tic-douloureux,  ul- 
ceration  of  the  eye,  photophobia,  blindness,  and  the  most 
excruciating  pain  of  the  ear.  The  internal  maxillary  artery 
is  the  principal  vessel  establishing  the  vascular  relationship 
between  the  mouth  and  brain,  and  other  parts  of  the  head 
and  face. 

In  congestion,  apoplexy,  and  delirium,  the  condition  of 
the  circulation  in  the  brain  is  reported  by  an  almost  similar 
state  of  the  circulation  in  the  mouth.  The  gums,  tongue, 
palate,  tonsils,  &c.,  by  the  same  kind  of  anatomical  rela- 
tionship of  blood-vessels  and  nerves,  display  each  their 
several  sympathies  with  the  other  portions  of  the  head. 

We  now  pass  to  the  second  division,  the  physiological  rela- 
tions of  the  mouth  with  the  different  parts  of  the  head. 

The  functions  of  the  mouth  have  been  stated  to  be  those 
of  prehension,  mastication,  insalivation,  suction,  deglutition, 
and  speech  ;  functions  lying  at  the  very  foundations  of  life 
and  connecting  man  with  the  outer  world. 

The  first  series  of  these  functions  comprises  the  commen- 
cing stages  of  digestion,  which  comprehend  the  preparatory 
but  essential  elements  in  that  grand  and  fundamental  pro- 
cess of  nutrition,  which  not  only  builds  up  the  head  in  all 
its  different  parts,  and  supplies  its  daily  and  unceasing 
waste,  but  further  preserves,  with  an  ever  vigilant  and  un- 
tiring care,  all  its  various  relations  with  the  mouth,  and 


RELATIONS  OP  THE  MOUTH  WITH  THE  HEAD.  439 

extends  its  influence  throughout  the  whole  and  every  part 
of  the  body. 

The  last  mentioned  function  of  the  mouth,  speech,  is  more 
closely  related  with  the  brain,  though  it  has  the  same  or- 
gans for  its  performance,  as  those  employed  in  the  above 
functions  of  the  first  stages  of  digestion.  For  this  function 
is  impaired  when  the  teeth  are  lost,  the  palate  cleft,  the 
tonsils  swollen,  or  the  lip  cleft,  and  it  is  partially  or  entirely 
lost  in  congestion  and  apoplexy  of  the  brain. 


PABTTHIRD, 

THE  LANGUAGE  OF  ANATOMY, 

II.  THE  TRUNK 


PART  THIRD. 


CHAPTEK  I. 

THE    TRUNK. 

PASSIVE    ORGANS    OF    THE    TRUNK. 
THE  BONES. 

Division. — 1.  Spine.     2.  Thorax.     3.  Pelvis. 

SECTION    I. 

THE   SPINE   OR  VERTEBRA. 

The  spine,  so  called  from  its  posterior  projecting  processes 
resembling  thorns,  is  situated  on  the  posterior  median  line 
of  the  trunk,  and  is  composed  of  a  column  of  bones,  called 
vertebral,  placed  one  above  the  other  in  a  regular  series  from 
top  to  bottom,  and  designated  the  vertebral  column. 

The  vertebrae  are  divided  into  true  and.  false.  The  twenty- 
four  movable  bones  are  the  true ;  the  sacrum  and  coccyx, 
which  assist  in  forming  the  pelvis,  the  false.  The  true  and 
false  vertebrae  form  an  upright  rod  or  column,  having  four 
curvatures,  one  in  the  neck,  concave  behind  and  convex  in 
front ;  a  second  in  the  back,  concave  in  front  and  convex 
behind ;  a  third  in  the  loins,  concave  behind  and  convex  in 
front,  and  a  fourth  in  the  pelvis,  concave  in  front  and  con- 
vex behind.  This  arrangement  is  found  to  add  greatly 
to  the  strength  of  the  spine,  and  results  from  the  difference 
in  the  thickness  of  the  bodies  of  the  several  vertebrae,  as 
well  as  of  the  intervening  fibro  cartilage. 

The  true  vertebras  are  divided  into  cervical,  dorsal, 
and  lumbar,  as  they  are  found  in  the  neck,  the  back,  or 
the  loins.  The  length  of  the  true  spine  is  estimated  as 
a  general  rule  at  twenty-four  inches;  six  inches  being 


444 


SPINAL  COLUMN. 


FIG.  122. 


allowed  to  the  cervical  and  lumbar 
portions  severally,  and  twelve  to  the 
back,  which  is  equal  to  the  other 
two  together. 

Common  characters  of  a  vertebra, 
Fig.  123. — Each  vertebra  consists  of 
a  body  and  processes.  The  body  is 
the  anterior,  thick,  and  middle  por- 
tion, of  a  cylindrical  form  and  sym- 
metrical. Its  surfaces  above  and 
below  are  flattened,  convex  in  front 
and  concave  behind.  Its  anterior 
and  posterior  surfaces  present  nu- 
merous foramina  for  the  passage  of 
the  vessels. 

The  processes  are  nine  in  number, 
two  lateral,  four  oblique,  two  trans- 
verse,  and  one  spinous,  which  are 
situated  upon  the  back  and  lateral 
parts  of  the  body.  The  lateral,  one 
on  each  side,  are  seen  to  arise  by  a 
pedicle  from  the  posterior  part  of 
the  body.  They  proceed  backward 
in  the  form  of  an  arch,  expanding  in 
their  course,  forming  the  lateral 
boundaries  of  the  spinal  canal,  and 
uniting  posteriorly  in  the  spinous 
process.  At  the  body  these  processes 
are  grooved  superiorly  and  inferi- 
orly  into  a  notch,  which,  being  ap- 
plied to  a  corresponding  notch  in 
the  adjacent  vertebra,  is  converted 
into  a  foramen  called  the  interver- 


Fi«.  122  represents  a  side  view  of  the  Spinal 
Column,  with  its  curvatures  and  internal  spongy 
structure,     a  Atlas,    b  Dentata.    c  Seventh  cer- 
^   I  vical  vertebra,     d  Twelfth  dorsal  vertebra,     t 

Fifth  lumbar.    /  First  bone  of  the  sacrum,    g  Last  bone  of  sacrum,    h  Coccyx. 
i  Spinous  process,     j  j  Intervertebral  foramina. 


SPIXAL  COLUMN. 


445 


tebral  foramen,  for   the  FlG-  123' 

passage   of   the    spinal 

nerves. 

The  spinous  process, 
formed  by  the  junction 
of  the  two  lateral,  is 
situated  on  the  posterior 
median  line,  and  consti- 
tutes the  most  project- 
ing part  of  the  vertebra. 
The  series  of  these  pro- 
cesses,, one  above  the 
other,  presents  a  long 
and  prominent  crest  be- 
hind, known  as  the  spine. 
The  use  of  these  processes  is  to  give  attachment  to  tendons 
and  muscles.  The  transverse  project  outward  from  the  lat- 
eral, nearly  at  right  angles,  and  also  give  attachment  to 
muscles,  and  in  the  back  sustain  the  ribs. 

The  oblique  or  articular  processes  are  two  on  each  side — 
one  superior,  the  other  inferior.  They  arise,  in  common 
with  the  transverse,  from  the  lateral.  Their  surfaces  are 
smooth,  covered  with  cartilage,  and  articulated  with  simi- 
lar processes  upon  the  adjacent  vertebrae  above  and  below. 

The  body  and  processes  thus  arranged  bound  a  foramen, 
which,  running  through  the  whole  series  of  vertebral  bones, 
constitutes  the  spinal  canal,  for  lodging  the  spinal  marrow. 

The  structure  of  the  body  (Fig.  123)  is  extremely  light 
and  spongy,  consisting  almost  entirely  of  the  cellular  or 
cancellated  tissue  of  bone.  The  processes  are  much  more 
compact  in  their  structure.  The  development  of  a  vertebra 
takes  place  generally  by  three  points  of  ossification,  one  for 
the  body  and  one  for  each  side.  In  addition  to  these  prin- 
cipal, there  are  five  other  accessory  points,  one  for  the 

FIG.  123  represents  a  Lumbar  Vertebra — its  upper  surface.  1  Spinous  pro- 
cess. 2  Same  process  connecting  with  the  lateral  lamina.  3  Superior  artic- 
ular process.  4  Transverse  process.  5  Inferior  articular  process.  6  7  Body 
of  the  vertebra.  9  Foramen  for  spinal  marrow. 


446  CERVICAL  VERTEBRA. 

spinous,  two  for  the  transverse,  and  one  for  the  upper  and 
lower  surfaces  of  the  body. 

The  three  primary  centres  present  their  ossific  points 
about  the  seventh  or  eighth  week,  those  of  the  lateral  por- 
tions being  observed  a  little  in  advance  of  the  body,  and  at 
birth  the  three  pieces  are  found  separate.  In  the  first  year 
union  begins  with  the  lateral  portions  and  at  their  poste- 
rior part,  where  they  come  together  to  form  the  spinous 
process,  and  during  the  third  and  fifth  year  with  the  body. 
The  osseous  nuclei  for  the  extremities  of  the  spinous  and 
transverse  processes,  are  seen  about  the  fifteenth  or  six- 
teenth year,  and  their  union  is  not  completed  till  the 
twenty-fifth  or  thirtieth  year. 

CERVICAL  VERTEBRAE — COMMON  CHARACTERISTICS. 

A      FIG.  124.    B  Thecervical vertebras  occupy  the 

superior  portion  of  the  column,  are 
seven  in  number,  and  are  the 
smallest  in  size.  The  superior  sur- 
face of  each  is  concave  from  side 
to  side_,  and  bounded  by  a  vertical 
ridge;  the  lower  surface  is  concave  from  before  backward, 
and  has  a  ridge  at  the  anterior  edge.  The  lateral  processes 
are  narrow  and  long,  and  bound  a  large  and  triangular 
canal. 

The  spinous  process  is  bifid,  short  and  horizontal.  The 
transverse  is  short  and  perforated  at  its  basb  by  a  foramen 
for  the  passage  of  the  vertebral  vessels.  Its  upper  surface 
is  grooved  for  the  cervical  nerves. 

FIG.  124,  A  represents  the  upper  surface  of  a  Cervical  Vertebra.  1  Spinous 
process  bifurcated.  2  Lateral  lamina.  3  Superior  articular  process.  4  Pos- 
terior surface  of  body.  5  Transverse  process  bifurcated.  6  Anterior  surface 
of  body.  7  Extremity  of  superior  articular  process.  8  Vertebral  foramen 
for  spinal  marrow. 

FIG.  124,  B  represents  the  lower  surface  of  the  same  vertebra.  1  Spinous 
process  bifurcated.  3  Posterior  root  and  notch  of  transverse  process.  5  Bi- 
furcation of  transverse  process,  and  the  process  showing  a  foramen  in  it  for 
giving  passage  to  the  vertebral  artery.  6  Body  of  vertebra.  7  Inferior  artic- 
ular process.  4  Foramen  for  the  spinal  marrow.  • 


CERVICAL  VERTEBRA  44 T 

The  oblique  articular  processes  are  oval,  the  two  superior 
being  directed  upward  and  backward,  and  the  two  inferior 
downward  and  forward ;  the  surfaces  of  the  superior  are 
rather  convex,  those  of  the  inferior  concave. 

CERVICAL    VERTEBRA — INDIVIDUAL  CHARACTERISTICS. 

The  atlas ,  or  first  cervical  vertebra,  so  called  from  sup- 
porting the  head,  differs  from  the  rest  in  having  no  body 
nor  spinous  process,  and  consisting  simply  of  a  bony  ring. 
A  tubercle  marks  this  ring  on  its  anterior  portion ;  behind, 
on  the  same  part,  the  A  FIG.  125.  B 

surface  is  concave, 
smooth,  and  oval,  for 
articulating  with  the 
tooth-like  process  of 
the  axis  or  second 
vertebra.  The  upper  and  lower  edges  of  this  ring  are  for 
the  attachment  of  ligaments.  The  posterior  arch  is  long, 
slender,  and  presents  a  tubercle  instead  of  a  spine,  upon 
the  upper  surface  of  which,  near  the  oblique  processes,  is  a 
groove  for  the  vertebral  artery,  in  making  its  curve,  to 
enter  the  brain.  It  also  receives  the  sub-occipital  or  first 
cervical  nerve.  The  spinal  foramen  is  very  large,  and 
divided  by  the  transverse  ligament  into  two ;  the  anterior 
and  smaller  receives  the  odontoid  process,  the  posterior  and 
larger  contains  the  spinal  cord.  The  intervertebral  notches 
are  behind  instead  of  being  in  front  of  the  oblique  processes, 
as  in  all  the  other  vertebras.  The  superior  oblique  pro- 
cesses are  horizontal,  concave,  and  their  smooth  surfaces 
look  from  before,  backward  and  outward ;  they  articu- 
late with  the  condyles  of  the  occipital  bone,  and  are  admi- 
rably adapted  to  the  nodding  motion  of  the  head.  The 

FIG.  125,  A  represents  the  upper  surface  of  the  Atlas.  1  Tubercle  in  place 
of  spinous  process.  2  Posterior  part  of  ring  of  atlas.  3  Where  the  transverse 
ligament  is  attached.  4  Superior  articular  process.  5  Groove  leading  to 
vertebral  foramen.  6  Transverse  process.  7  Articular  surface  for  odontoid 
process.  8  Anterior  margin  of  ring  of  atlas.  9  Foramen  for  spinal  marrow. 

FIG.  125,  B  represents  the  lower  surface  of  Atlas.  1  Tubercle  in  place  of 
spinous  process.  23456789  Correspond  to  similar  points,  as  in  Fig.  125,  A. 


448 


CERVICAL   VERTEBB^E. 


inferior  are  circular,  nearly  flat,  and  suited  to  the  rotatory 
motion.  The  transverse  processes  are  noted  for  their  great 
length — projecting  much  beyond  those  below,  and  have  the 
foramen  at  their  base  for  the  passage  of  the  vertebral 
artery. 

The  axis,  or  second  cervical  vertebra,  is  also  called  the 
dentata  from  its  tooth-like  or  odontoid  process,  which  is  the 
FIG.  126.  peculiar  characteristic  of  this  vertebra. 

This  process  arises  from  the  central  part 
of  the  superior  surface  of  the  body,  and 
ascends  vertically.  It  presents  some- 
what the  form  of  a  tooth — hence  its 
name.  Its  anterior  surface  is  smooth, 
/£  ~  and  articulates  with  the  anterior  arch  of 
the  atlas.  Its  posterior  is  also  smooth,  and  has  the  trans- 
verse ligament  in  connection  with  it.  Its  apex  is  pointed 
for  the  attachment  of  the  vertical  ligament,  and  upon 
each  side,  from  a  rough  surface,  originate  the  moderator  or 
FIG.  127.  check  ligaments.  This  process  is  the 

pivot  round  which  turns  the  atlas.  The 
spinous  process  is  long,  large,  and 
forked.  The  spinal  foramen  is  heart- 
shaped.  The  superior  oblique  processes 
are  seen,  on  each  side  of  the  odontoid, 
on  a  plane  anterior  to  those  below,  and 
are  smooth,  circular,  and  nearly  hori- 
zontal. The  inferior  look  forward  and  downward,  and 
are  flat.  The  transverse  processes  are  short  and  not 
bifid — the  body  of  this  vertebra  is  large.  The  cervical  ver- 
tebras increase  gradually  in  size  to  the  seventh,  (Fig.  12*7.) 
The  seventh  cervical  is  called  vertebra prominens ,  from  its 

FIG.  126  represents  the  Dentata  or  second  bone  of  the  Vertebrae,  a  Body. 
6  Odontoid  process,  c  Articular  face  for  atlas,  d  Foramen  for  vertebral 
artery,  e  Spinous  process.  /  Inferior  oblique  process,  g  Superior  oblique 
process. 

FIG.  127  represents  the  seventh  cervical  vertebra,  seen  from  below.  1 
Spinous  process.  2  Vertebral  foramen.  3  Articular  process.  4  Lateral 
lamina.  5  Foramen  for  vertebral  artery  and  vein.  6  Germ  of  the  accessory 
rib.  7  Supernumerary  rib  at  its  styloid.  8  Body. 


DORSAL  VERTEBRA.  449 

long  spinous  process,  which  projects  beyond  all  the  rest 
and  is  readily  felt  beneath  the  skin,  ends  in  a  tubercle 
and  is  not  bifurcated,  and  gives  attachment  to  the  liga- 
mentum  nuchae.  Its  transverse  processes  have  no  foramina, 
or  if  there  be  any,  they  are  small  and  transmit  only  a  vein. 

PECULIARITIES  OF  DEVELOPMENT  IN  THE  CERVICAL  VERTEBRA. 

The  atlas,  instead  of  the  usual  three  primary  ossific  cen- 
tres, is  seen  to  have  four  and  sometime's  five ;  one  for  each 
lateral  portion,  one,  occasionally  two,  for  the  anterior  arch, 
and  one  for  the  centre  of  the  posterior  arch.  The  lateral 
centres  unite  with  the  posterior  centre  during  the  second 
and  third  years,  and  with  the  anterior  about  the  fifth  or 
sixth  year.  The  axis  is  found  with  five  centres  of  ossifica- 
tion, two  for  the  odontoid  process,  one,  sometimes  two,  for 
the  body,  and  one  for  each  lateral  part.  The  body  and 
odontoid  process  begin  ossifying  about  the  sixth  month,  and 
are  found  united  about  the  third  or  fourth  year.  The  lat- 
eral portions  unite  soon  after  birth,  and  join  the  body 
about  the  fourth  or  fifth  year. 

The  seventh  cervical  vertebra  is  found  to  have  the  anterior 
portion  of  its  transverse  process  frequently  presenting  a 
separate  osseous  centre  about  the  second  or  sixth  month, 
which  unites  with  the  body  about  the  fifth  or  sixth  year. 
Separate  ossific  centres  have  also  been  noticed  in  the  trans- 
verse processes  of  the  second,  fifth  and  sixth  cervical  verte- 
bra?, and  also  the  first  lumbar. 

DORSAL  VERTEBRAE — COMMON  CHARACTERISTICS.     (Fig.   128.) 

The  dorsal  vertebras  occupy  an  intermediate  position  be- 
tween the  cervical  and  lumbar,  and  are  also  intermediate 
in  size;  they  become  less  and  less  from  the  first  to  the  third 
or  fourth,  and  then  increase  to  the  last.  The  body  is  thicker 
behind  than  before,  and  more  cylindroid  than  those  of  the 
neck ;  the  upper  and  lower  surfaces  at  the  posterior  edge, 
near  the  origin  of  the  lateral  processes,  present  two  small 
articular  facets  for  receiving  one  half  of  the  head  of  each 
rib — the  adjoining  vertebra  having  a  corresponding  de- 
29 


450  LUMBAR  VERTEBRA. 

A     F      128      B  pression   for   the    other    half. 

The  lateral  processes  are 
"broad.  The  spinous  are  trian- 
gular, long,  ending  in  a  tuber- 
cle and  bending  downward  so 
as  to  overlap  each  other.  The 
oblique  processes  are  vertical — 

the  superior  facing  directly  backward — the  inferior  as  di- 
rectly forward.  The  spinal  foramen  is  round  and  large. 
The  transverse  processes  are  directed  backward,  are  large 
and  long,  and  have  their  front  surfaces  at  the  extremities 
smooth,  for  articulation  with  the  tubercle  of  the  ribs.  This 
is  true  of  all  except  the  last  two;  they  have  no  articulating 
surfaces.  The  intervertebral  foramina  for  the  nerves  are 
large. 

DORSAL  VERTEBRA — INDIVIDUAL  CHARACTERISTICS. 

The  first  and  the  last  two  dorsal  present  individual  pecu- 
liarities. The  first  has  a  full  articulating  surface  on  each 
side,  and  receives  the  whole  head  of  the  first  rib,  and  also 
has  at  its  inferior  edge  a  half  articular  surface  for  the  half 
head  of  the  second  rib.  The  flatness  of  the  body  and  its 
projecting  spinous  process  resembles  it  to  the  cervical.  The 
three  lower  dorsal  approximate  in  their  appearance  to  those 
of  the  loins.  They  have  full  depressions  in  the  middle  and 
sides,  for  their  corresponding  ribs,  and  the  last  two  have 
no  articular  surfaces  on  their  transverse  processes.  The 
tenth  dorsal  has  occasionally  on  its  transverse  process  the 
articular  face. 

LUMBAR  VERTEBRAE — COMMON  CHARACTERISTICS.    (Fig.  129.) 

The  lumbar  vertebrae  are  five  in  number;  occupy  the 
lower  part  of  the  column,  and  are  much  the  largest  in  size 

FIG.  128,  A  represents  a  dorsal  vertebra  seen  from  above.  1  Spinous  pro- 
cess. 2  Transverse  process.  3  Articular  facet  for  the  articulation  of  the  rib. 
4  5  Articular  process  and  notch.  6  7  Body.  8  Foramen  for  spinal  marrow. 

FIG.  128,  B  represents  a  side  view  of  the  same  vertebra.  1  Body.  2  Ar- 
ticular face  for  head  of  the  rib.  3  Superior  articular  process.  4  5  Transverse 
process  and  articular  face.  6  Spinous  process.  7  Inferior  articular  process. 
8  Notch,  intervertebral. 


PELVIC  VERTEBRA.  451 

of  all  the  true  vertebrse.  The  bodies  are  deeper  FIG.  129. 
before  than  behind,  and  broad  transversely. 
The  superior  and  inferior  surfaces  are  flat  and 
oval,  having  projecting  and  hard  edges.  The 
intervertebral  notches  are  very  large,  especial- 
ly the  lower — the  spinal  foramen  is  triangular 
or  oval,  and  larger  than  in  the  dorsal.  The  spinous  pro- 
cess is  broad,  thick,  and  short,  ending  in  a  rough  border. 
The  oblique  processes  are  vertical— the  superior  being  con- 
cave and  looking  inward — the  inferior  convex  and  looking 
outward  and  forward.  The  transverse  are  long,  slender,  and 
stand  at  right  angles.  The  fifth  or  last  lumbar  vertebra 
is  somewhat  peculiar  in  having  its  body  of  greater  size, 
deeper  generally  in  front  than  behind,  so  as  to  give  some- 
thing of  the  wedge  shape  ;  in  its  transverse  processes  being 
thick,  short,  and  round,  and  in  the  spinal  foramen  being 
larger. 

The  false  or  pelvic  vertebrce  consist  of  the  sacrum  and 
coccyx. 

The  sacrum  is  situated  at  the  lower  part  of  the  true  ver- 
tebrae, occupying  the  posterior  and  superior  portion  of  the 
pelvis.  Its  form  is  triangular,  and  its  position  is  like  that 
of  a  wedge,  its  base  being  above,  and  apex  below — having 
the  innominata  laterally — the  lumbar  vertebra  upon  its 
superior,  and  the  coccyx  on  its  inferior  portion.  This  bone, 
in  the  adult  consisting  of  one  piece,  in  the  child  forms  five 
pieces.  Its  surfaces  are  the  anterior,  posterior,  and  two 
lateral. 

The  anterior  surface  is  concave  from  above  downward, 
and  marked  by  four  transverse  lines,  showing  the  original 
divisions  of  the  bone  into  five  pieces.  At  the  outer  extrem- 
ity of  these  lines  four  foramina  are  observed,  called  the 
anterior  sacral  foramina,  for  transmitting  the  anterior  sa- 
cral nerves.  The  two  superior  of  these  foramina  are  quite 
large — the  rest  diminish  in  size  as  they  descend ;  they  are 

FIG.  129  represents  the  upper  surface  of  a  lumbar  vertebra.  1  Spinous  pro- 
cess. 2  Lateral  lamina.  3  Superior  articular  process.  4  Transverse  process. 
6  7  Body.  8  Vertebral  foramen. 


452  PELVIC  VERTEBRAE. 

all  smooth,  funnel-shaped,  and  have  their  orifices  looking 
outward.  The  anterior  projecting  edge  of  the  upper  l><>m' 
of  the  sacrum  is  called  its  promontory. 

The  posterior  surface  is 
rough  and  convex ;  on  its 
middle  line  four  promi- 
nences are  observed  cor- 
responding to  spinous 
processes,  which  are  not 
unfrequently  seen  united 
into  a  single  ridge  or 
crest.  The  fourth  and 
fifth  spines  are  generally  deficient,  leaving  a  triangular 
space  which  is  simply  closed  by  ligaments,  and  in  place 
of  the  spine,  presenting,  on  either  side,  two  tubercles 
styled  comua,  which  unite  with  similar  cornua  from  the 
coccyx,  forming  foramina  for  the  passage  of  the  last  sacral 
nerve. 

On  either  side  of  the  spinous  processes  four  foramina 
are  seen,  smaller  than  those  in  front,  transmitting  the  pos- 
terior sacral  nerves.  External  to  these  foramina,  a  row  of 
five  tubercles  is  noticed,  though  indistinct,  corresponding  to 
the  transverse  processes  of  the  true  vertebrae ;  and  internal 
to  these  foramina,  between  them  and  the  spinous  processes, 
another  row  of  indistinct  tubercles  is  seen,  regarded  as 
analogous  to  the  oblique  processes. 

The  lateral  or  iliac  surfaces  are  rough,  irregular,  and 
triangular,  having  their  superior  portions  broad  and  cov- 
ered with  cartilage  to  articulate  with  the  ilium.  Their 
inferior  surfaces  are  thin,  and  give  attachment  to  the 
greater  and  lesser  sacro-ischiatic  ligaments. 

Fio.  130,  A  represents  a  front  view  of  the  Sacrum.  1  Superior  articular 
process.  2  Superior  surface  of  first  sacral  vertebra.  3  Lateral  side  of  sa- 
crum. 4  Anterior  surface  of  the  bodies  of  the  sacral  vertebra.  5  Grooves 
leading  to  the  anterior  sacral  foramina.  16  Apex  of  last  sacral  vertebra. 

Fio.  130,  B  represents  a  side  view  of  the  Sacrum.  1  Superior  articular 
process.  2  Sacro  vertebral  angle.  3  Hollow  of  the  sacrum.  4  Termination 
of  sacral  canal.  5  Articular  surface  for  coccyx.  888  Spinous  processes,  or 
crest. 


PELVIC  VERTEBRAE.  453 

/  On  the  upper  surface,  in  the  centre,  is  an  oval  articula- 
ting surface  for  uniting  with  the  last  lumbar  vertebra.  On 
each  side  of  this  is  seen  a  broad  triangular  expansion,  upon 
which  rests  the  psoas  magnus  muscle,  and  lumbo-sacral 
nerve.  The  anterior  edge  of  this  expansion  is  continuous 
with  the  linea  ileo-pectinea.  Between  this  expansion  and 
the  oblique  process  is  a  groove  for  the  fifth  lumbar  nerve. 
The  lower  extremity  of  the  sacrum  is  truncated  and  pre- 
sents a  small  oval  surface  for  articulation  with  the  coccyx. 

The  structure  of  the  sacrum  is  mostly  spongy  and  cancel- 
lated, thick,  yet  very  light,  and  covered  by  a  thin  compact 
layer.  Its  development  occurs  usually  from  twenty-one 
points  of  ossification ;  five  for  each  of  the  three  superior 
divisions,  one  for  the  body,  one  for  each  lamina,  and  one 
for  each  lateral  portion.  The  two  lower  divisions  have  each 
three  points,  one  for  the  body  and  one  for  each  lateral  por- 
tion. As  many,  however,  as  thirty-four  and  thirty-five 
points  of  ossification  have  been  observed.  Ossification  is 
observed  to  commence  in  the  bodies  of  the  three  upper  sa- 
cral vertebras,  about  the  eighth  or  ninth  week,  a  little  later 
than  that  of'  the  true  vertebrae,  in  the  two  lower  about  the 
fifth  month,  and  in  the  lateral  portions  from  the  sixth  to 
the  ninth  month.  The  union  of  these  latter  with  the  body 
is  found  to  take  place  from  below  upward,  and  in  the  fol- 
lowing order :  the  fifth  piece  about  the  second  year,  and  the 
first  not  before  the  fifth  or  sixth  year.  The  epiphyses  are 
developed  about  the  fifteenth  or  eighteenth  year,  and  the 
sacrum  is  completely  fused  into  one  piece  by  the  thirtieth 
year. 

It  is  articulated  above  with  the  last  lumbar  vertebrae, 
below  with  the  coccyx,  and  laterally  with  the  two  ossa 
innominata. 

Coccyx — (xoxxvf ,  cuckoo,  from  likeness  to  a  cuckoo's  beak,) 
is  situated  at  the  lower  extremity  of  the  sacrum,  and  cor- 
responds to  the  tail  of  the  inferior  animals,  (Fig.  131.)  It 
consists  of  four  caudal  vertebrae,  sometimes  only  three, 
which  in  the  old  are  often  consolidated  into  two  or  a  single 
piece.  Its  shape  is  triangular,  the  base  above,  broad  and 


454  LIGAMENTS  OF  THE  SPINE. 

articulating  with  the  sacrum.  Upon  each  side  of  the  base  at 
Fio  131      ^s  posterior  part,  a  small  process  or  cornu  arises 
to  unite  with  a  similar  one  upon  the  sacrum, 
forming  a  foramen  for  the  passage  of  the  fifth 
sacral  nerve.     The  three  lower  pieces  diminish 
in  size  to  the  last,  and  in  old  age,  as  already 
stated,  become  firmly  fused  together  and  also 
with  the  sacrum,  presenting  one  solid  piece. 

The  anterior  or  pelvic  surface  of  the  coccyx  is  smooth, 
concave,  and  marked  by  three  transverse  lines,  denoting  its 
original  separation  into  four  pieces.  This  surface  supports 
the  rectum.  The  posterior  surface  is  rough,  presenting 
ridges  and  tubercles  to  which  ligaments  and  muscles  are 
attached. 

The  coccyx  is  light  and  spongy.  Its  development  is  from 
four  points,  one  to  each  piece.  Ossification  in  the  coccyx  is 
noticed  soon  after  birth  in  the  first  piece,  from  five  to  ten 
years  in  the  second ;  from  ten  to  fifteen  in  the  third ;  and 
from  fifteen  to  twenty  in  the  fourth  piece ;  the  several  pieces 
unite  in  pairs — the  first  in  order  are  the  two  first  pieces, 
then  the  third  and  fourth,  and  lastly  the  second  and  third; 
and  between  forty  and  sixty  years  the  coccyx  becomes 
united  with  the  sacrum.  Its  union  with  the  sacrum  by 
fusion,  is  much  earlier  in  the  male  than  in  the  female. 

LIGAMENTS  OP  THE  SPINE — COMMON  ARTICULATIONS  OF  THE 
VERTEBRAL  COLUMN. 

1.  The  anterior  vertebral  ligament,  (Fig.  132,)  as  its  name 
implies,  is  situated  on  the  front  surface  of  the  spinal  column, 
extending  from  the  axis  to  the  sacrum,  and  consists  of  fibres 
which  are  broad  and  strong,  increasing  in  breadth  as  they 
descend,  and  adhering  more  strongly  to  the  intervertebral 
matter,  than  to  the  bodies  themselves.  The  fasciculi  of 
this  ligament  vary  in  length  and  thickness.  The  super- 
ficial fibres  are  long  and  run  to  several  vertebras.  The 

FIG.  131  represents  a  front  view  of  the  Coccyx.  1  Upper  articular  surface 
for  last  lumbar  vertebra.  2  Cornu  of  coccyx.  3  Transverse  process.  444 
Margin  of  the  four  bones. 


LIGAMENTS   OF  THE  SPINE. 


455 


deep  ones  are  short  and  ex-  FIG.  132. 

tend  simply  to  adjoining  ver- 
tebrae. It  is  thin  in  the  neck, 
thicker  in  the  back,  and  again 
becomes  thin  in  the  loins.  The 
use  of  this  ligament  is  to 
bind  together  the  several  ver- 
tebrae, and  prevent  over-ex- 
tension of  the  spine. 

2.  The  posterior  vertebral  ligament  (Fig.  133)  is  situated 
upon  the  back  part  of  the  bodies  of  the  spinal  column,  within 
the  canal,  and  extends  from  the  axis  to  the        FIG.  133. 
sacrum,  the  fibres  being  traced  still  higher 

to  the  cuneiform  process  of  the  os-occipitis, 
and  lower  to  the  coccyx.  This  ligament 
has  its  fibres  arranged  in  a  similar  manner 
to  the  anterior,  consisting  of  short  and  long. 
It  is  broad  over  the  intervertebral  substance, 
to  which  it  is  also  more  adherent.  It  is 
loose  upon  the  bodies,  being  separated  by 
the  veins  which  escape  from  the  large 
foramina  seen  on  this  surface.  This  liga- 
ment antagonizes  the  former  by  opposing  excessive  flexion 
of  the  spine,  while,  at  the  same  time,  it  assists  in  binding 
together  and  strengthening  the  several  vertebrae. 

3.  Intervertebral  ligaments  are  situated  between  the  bodies 
of  each  vertebra,  except  the  first  and  second.     Their  struc- 
ture is  of  a  mixed  character,  partaking  both  of  ligament  and 
cartilage,  hence  called  also  fbro-cartilages.    They  are   so 
strongly  united  to  the  upper  and  lower  surfaces  of  the 
vertebrae,  that  it  requires  even  maceration  for  a  complete 
separation. 

FIG.  132  represents  the  Anterior  Vertebral  Ligament.  1  Anterior  vertebral 
ligament.  2  Anterior  costo-vertebral  ligament.  3  Internal  transverse  liga- 
ment. 4  Inter-articular  ligament. 

FIG.  133  represents  the  Posterior  Vertebral  Ligament,  a  a  Intervertebral 
•ubstance.  6  6  Surfaces  of  bony  bridges  where  cut.  c  Posterior  vertebral 
ligament,  d  Opening  for  a  vertebral  vein. 


456  LIGAMENTS  OF  THE  SPINE. 

Their  thickness  varies  in  different  parts.  In  the  neck 
and  loins  the  thickness  is  greater  before  than  behind — 
while  in  the  back  it  is  less.  The  curves  of  the  spine  are 
due,  in  great  measure,  to  this  substance.  A  transverse 
Section  of  this  ligament  shows  its  fibres  to  run  in  a  concen- 
tric form,  being  very  close  and  compact  near  the  surface, 
and  as  they  approach  the  centre,  spaces  or  interstices  are 
left,  containing  a  soft,  pulpy,  semi-fluid  substance,  while 
in  the  centre,  the  spaces  become  still  wider  and  more  cellu- 
lar, and  present  still  more  of  the  pulpy  matter.  This  cen- 
tral pulpy  and  conical  body  is  a  movable,  elastic  fulcrum, 
upon  which  the  different  vertebrae  turn.  It  is  more  abun- 
dant, softer,  whiter,  and  more  transparent,  in  proportion,  in 
infancy,  than  in  any  after  period.  In  old  age  it  diminishes 
both  in  quantity  and  elasticity,  which  accounts,  in  some 
measure,  for  the  stiffness  of  the  spine  in  old  people. 

The  use  of  the  intervertebral  ligaments  is  manifold. 
They,  in  common  with  those  just  described,  tie  the  several 
vertebrae  together ;  they  help  to  form  the  spinal  canal, 
give  sockets  to  the  heads  of  the  ribs,  allow  the  flexibility 
of  which  the  spine  is  capable ;  and,  by  their  elasticity,  pre- 
serve the  spine  of  its  uniform  height :  they  also  lessen  the 
effects  of  shocks  from  concussion. 

4.  Ligamenta  subflava,  or  yellow  ligaments,  (Fig.    134.) 
These  ligaments  close  the  spinal  canal  behind,  and  are 
FIG.  134.  situated   between    the    posterior 

arches  of  the  different  vertebra?. 
They  are  found  between  all  the 
vertebrae  from  the  axis  to  the  sa- 
crum. They  are  in  pairs,  on  each 
side  of  the  median  line,  and  are 
twenty-three  in  number.  They  ex- 
tend from  the  inferior  margin  of 
the  lamina  above,  to  the  superior 
margin  of  the  corresponding  one 
below.  Their  structure  consists  of  yellow  elastic  tissue. 

Fig.  134  represents  the  Yellow  Ligaments  (ligamenta  flava.)  a  a  One  pair 
of  the  yellow  ligaments.  6  Capsular  ligament  of  the  one^  side. 


ARTICULATIONS  OP  THE  VERTEBRA.  45 1 

dense,  very  strong,  and  having  the  fibres  vertical.  They 
oppose  flexion,  and  by  their  elasticity  restore  the  spine  to 
its  erect  condition. 

5.  The  Supra-spinous  ligament  is  found  at  the  extremity 
of  the  spinous  processes,  from  the  last  cervical  vertebra  to 
the  sacrum.     In  the  neck  it  is  continued  on  to  the  occipital 
bone,  under  the  title  of  ligamentum  nuclice.    It  separates  the 
muscles  on  either  side  of  the  median  line,  and  is  the  rudi- 
mentary structure  of  this  very  powerful  ligament  in  the 
lower  animals. 

6.  The  Inter-spinous  ligaments  are  situated  between  the 
gpinous  process  of  the  dorsal  and  lumbar  regions,  above  and 
below,  and  not  between  those  of  the  neck.     They  are  thin  in 
the  back,  and  thicker  and  stronger  in  the  loins,  and  have 
the  multifidus  spinge  muscles  attached  to  them. 

T.  The  Inter-transverse  ligaments  are  situated  between 
the  transverse  processes  of  the  lower  dorsal  and  lumbar 
vertebrae,  not  being  distinct  either  in  the  cervical  or  upper 
dorsal.  They  consist  of  thin  fibrous  membranes. 

8.  Articulation  of  the  oblique  processes. — These  processes 
have  an  irregular  capsule,  consisting  of  ligamentous  fibres 
not  fully  developed,  extending  from  one  bone  to  the  other. 
Their  articular  surfaces  are  covered  with  cartilage,  and 
connected  by  synovia!  membranes. 

PECULIAR   ARTICULATIONS   OF   THE   VERTEBRAL  COLUMN. 

1.  Articulation  of  the  atlas  with  the  occiput. — The  condyles 
of  the  occipital  bone,  and  the  oblique  processes  of  the  atlas, 
are  the  bony  portions  especially  concerned  in  the  joint. 
There  is  the  usual  cartilage  and  synovial  membrane  at  this 
joint;  and  also  a  ligamentous  capsule,  or  capsular  ligament 
on  each  side,  which  is  attached  to  the  circumference  of  the 
condyles  and  the  margin  of  the  glenoid  cavity  of  the  atlas. 
This  capsule  consists  of  thin  and  loose  fibres  which  are, 
however,  strong  at  the  anterior  and  external  parts. 

Anterior  ligaments,  (anterior  occipito-atloid.) — These  are 
two  in  number,  one  a  strong,  round  cord,  situated  on  the 
median  line,  and  extending  from  the  basilar  process  to 


458  ARTICULATIONS  OF  THE  VERTEBRA. 

the  anterior  tubercle  of  the  atlas ;  the  second,  deeper  than 
this,  is  broad  and  membranous,  and  extends  from  the  ante- 

A  FIG.  135.  B 


rior  margin  of  the  foramen  magnum,  to  the  anterior  arch 
of  the  atlas.  These  ligaments  are  covered  in  front  by  the 
anterior  recti  muscles,  and  behind  are  in  relation  with  the 
dura  mater. 

The  posterior  occipito-atlantal  ligament  is  attached  above  to 
the  occipital  foramen,  and  below  to  the  posterior  arch  of  the 
atlas.  It  is  composed  of  a  broad,  thin  and  weak  membrane, 
closely  adheres  to  the  dura  mater,  gives  passage  to  the  ver- 
tebral arteries  and  sub-occipital  nerves,  and  is  covered  by 
the  posterior  recti  and  oblique  muscles. 

The  lateral  ligaments,  one  on  each  side,  extend  from  the 
transverse  process  of  the  atlas,  to  the  transverse  process  of 
the  occiput,  they  consist  of  strong  fasciculi  of  fibres,  which 
expand  and  are  continuous  with  the  sheath  surrounding 
the  carotid  vessels  and  nerves  at  the  base  of  the  brain. 

2.  Articulation  of  the  axis,  or  dentata,  with  the  occiput. — The 
ligaments  connecting  the  axis  or  second  vertebra  with  the 

FIG.  135,  A  represents  an  anterior  view  of  the  Ligaments  which  connect  the 
first  and  second  vertebrae  with  the  occiput,  a  Anterior  occipito-atloid  liga- 
ment, b  Anterior  annular  ligament,  c  Where  anterior  vertebral  ligament 
begins,  d  e  Capsular  ligament  of  oblique  processes  of  atlas  and  dentata.  / 
Joint  between  first  and  second  cervical  vertebrae,  g-  External  fibres  of  anterior 
annular  ligament. 

FIG.  135,  B  represents  a  posterior  view  of  the  ligaments  which  connect  the 
first  and  second  vertebra  with  i\m  occiput,  a  Atlas,  b  Dentata.  c  Posterior 
occipito-atloid  ligament,  d  d  Capsular  ligament  of  oblique  processes  of  the 
atlas  and  occipital  condyles.  e  Ligament  between  the  first  and  second  verte- 
brae. //  Lateral  fasciculi  of  this  latter  ligament,  g  First  pair  of  the  yellow 
ligaments,  h  Capsular  ligament  between  the  oblique  processes  of  the  second 
and  third  vertebrae. 


ARTICULATIONS  OF  THE  VERTEBRA.  459 

occiput,  are  three,  the  middle  straight  and  two  moderator 
ligaments.  The  middle  straight  ligament^  called  occipito- 
axoid  or  apparatus  ligamentosus  colli,  consists  of  a  broad, 
thick  hand  of  fibres  which  extend  from  the  cuneiform  pro- 
cess, forming  the  foramen  magnum,  to  the  summit  of  the 
odontoid  process,  and  pass  on  behind  this  process  to  be  at- 
tached to  the  superior  central  FIG.  136. 
portion  of  the  transverse  liga- 
ment of  the  atlas — and  still 
lower  down  into  the  body  of  the 
second  vertebra  and  into  the 
bodies  of  the  third*  and  fourth, 
where  they  are  Continuous  with 
the  posterior  common  ligament. 

The  moderator  or  oblique  ligaments,  (Fig.  136,)  called  also 
the  lateral  alar  or  check  ligaments,  extend  from  each  side  of 
the  odontoid  process  obliquely,  upward  and  outward,  to  be 
attached  above  to  the  inner  edge  of  each  condyle. 

Tnese  ligaments  are  short,  thick,  and  strong,  and  limit 
the  extent  of  rotation.  They  have  in  front  the  anterior 
occipito-atlantal  ligaments  and  some  cellular  tissue,  and 
behind  the  middle  straight  ligament. 

3.  Articulation  of  the  atlas  with  the  axis  or  dentata. — The 
ligaments  of  this  articulation  are  five,  (Fig.  136.)  The 
transverse,  anterior  and  posterior  atlanto-axoid,  and  two 
capsular. 

The  transverse  is  situated  behind  the  odontoid  process, 
crossing  the  area  of  the  atlas  from  the  inner  edge  of  the 
oblique  process  on  the  one  side,  to  the  same  point  on  the 
opposite.  It  is  a  strong,  thick,  ligamentousband,  concave, 
and  smooth  anteriorly,  having  a  synovial  membrane,  and 
connected  at  this  point  with  the  odontoid  process,  forming 
a  joint.  At  its  centre,  behind  the  process,  some  of  its  fibres 
ascend  to  join  the  middle  straight  ligament,  and  others 

FIG.  136  represents  the  ligaments  which  unite  the  atlas  and  dentata  with  the 
occiput.  1  Posterior  vertebral  ligament,  its  upper  portion.  2  Transverse 
ligament.  3  4  Appendices  of  transverse  ligament.  5  Moderator  or  check 
ligament.  6  7  Capsular  ligaments. 

X. 


460  THE  THORAX. 

descend  to  be  attached  to  the  body  of  the  axis,  presenting, 
as  seen,  in  the  figure  above,  a  crucial  appearance.  The  use 
of  this  ligament  is  to  retain  the  odontoid  process  and  the 
atlas  in  secure  connection  with  each  other. 

The  anterior  atlanto-axoid  ligament  extends  from  the  ante- 
rior tubercle  and  arch  of  the  atlas  to  the  base  of  the  odon- 
toid process,  and  is  continuous  with  the  anterior  vertebral 
ligament.  It  is  strong  and  thick. 

The  posterior  atlanto-axoid  is  situated  between  the  pos- 
terior arch  of  the  atlas,  and  the  lamina  of  the  axis ;  it 
corresponds  to  the  ligamenta  sub-flava,  is  a  thin,  broad,  and 
weak  membrane,  but  not  elastic. 

The  capsular  ligaments  are  two  in  number,  one  on  each 
side,  and  belong  to  the  oblique  processes  of  the  atlas  and 
axis.  They  surround  the  margins  of  these  processes,  and 
are  loose  enough  to  allow  freedom  of  motion.  They  are, 
like  all  the  oblique  articulations,  lined  with  synovial  mem- 
brane, which  occasionally  communicates  with  the  syno- 
vial membrane  of  the  transverse  ligaments  and  odontoid 
process. 

The  ligaments  of  the  false  vertebree — the  sacrum  and 
coccyx,  will  be  noticed  along  with  those  of  the  pelvis. 

SECTION   II. 
THE  THORAX  OR  CHEST. 

The  chest  forms  the  upper  part  of  the  trunk,  and  is  com- 
posed of  the  sternum  and  costal  cartilages  in  front — the  ribs 
laterally,  and  the  dorsal  vertebrae,  which  have  already 
been  considered,  behind.  Its  form  is  conoidal,  flattened  in 
front,  rather  concave  behind,  and  convex  upon  the  sides. 
Its  summit  or  superior  portion  is  smaller  than  the  inferior 
or  base,  and  presents  a  very  oblique  opening ;  cordiform  in 
its  shape,  and  much  lower  in  front  than  behind.  The  base 
is  a  large  foramen,  bounded  by  the  lateral  and  posterior 
margins  of  the  lower  ribs  and  their  cartilages,  marking  the 
situation  of  the  diaphragm. 

The  sternum  (attpvov,  the  breast)  is  situated  on  the  me- 

'  : 


THE  STERNUM. 


461 


dian  line  at  the  front  part  of  the  thorax.  Its  direction  IB 
obliquely  downward  and  forward,  its  superior  end  being 
consequently  nearer  the  spine  than  the  inferior.  Its  upper 
portion  is  on  a  A  FIG.  137. 

level  with  the 
third  dorsal, 
and  its  lower 
with  the  elev- 
enth dorsal  ver- 
tebra. Its  ave- 
rage length  is 
six  inches. 

The  sternum, 
in  the  adult, 
consists  of  three 
pieces — a  supe- 
rior, middle,  and 
inferior,  which, 
in  old  age,  are 
often  fused  into  one.  The  superior  lone  is  quadrilateral  in 
shape,  thick  and  broad  above,  narrow  below,  and  concave 
transversely  at  its  upper  edge.  The  interclavicular  liga- 
ment occupies  this  concavity,  at  either  end  of  which,  corre- 
sponding to  the  angles,  are  the  articular  cavities  for  the 
sternal  ends  of  the  clavicle.  Just  below  this  articulation 
is  a  depression  on  each  side  for  the  cartilage  of  the  first  rib, 
and  still  lower  down,  at  the  point  of  junction  with  the 
second  piece,  there  is,  on  each  side,  a  half  fossa,  which,  with 
a  similar  one  upon  the  second  bone,  receives  the  cartilage 
of  the  second  rib.  The  middle  lone  is  much  longer  than 

Fia.  137,  A  represents  a  front  view  of  the  Chest,  a  First  bone  of  the  ster- 
num. 6  Second  bone  of  sternum,  c  Third  bone  of  sternum,  called  ensiform 
cartilage,  d  First  dorsal  vertebra,  e  Twelfth  dorsal  vertebras.  /First  rib. 
g  Head  of  first  rib.  h  Neck,  t  Tubercle,  j  Seventh  or  last  true  rib.  k  k  Cos- 
tal cartilages.  I  Floating  ribs,  m  Groove  for  the  intercostal  artery. 

FIG.  137,  B  represents  the  Sternum,  a  First  piece.  6  Second  piece,  c 
Third  piece,  or  ensiform  cartilage,  d  Articular  face  for  clavicle,  e  Articu- 
lar surface  for  first  rib.  /  Articular  surface  for  second  rib.  g  h  i  j  Articular 
•urfaces  for  the  last  five  true  ribs. 


462  THE  STERNUM. 

the  upper ;  it  is  wide  in  the  centre,  and  narrow  at  either 
end;  its  sides  furnish  cavities,  complete  for  the  third, 
fourth,  fifth,  and  sixth  ribs,  and  half  cavities  for  the  second 
and  seventh  ribs.  These  cavities  approach  nearer  each 
other  as  they  descend,  so  that  the  sixth  and  seventh  are  in 
contact. 

The  inferior,  or  third  bone,  called  ensiform,  or  xiphoid 
cartilage,  being  usually  in  the  cartilaginous  state  in  the 
adult,  is  the  smallest  of  the  three  pieces.  It  is  thin,  and 
varies  much  as  to  form  and  size,  being  sometimes  pointed, 
sometimes  bifid,  sometimes  thick — looking  forward,  and 
then  backward,  and  occasionally  perforated  with  a  central 
foramen.  Its  base  is  united  to  the  lower  extremity  of  the 
middle  bone ;  its  sides  have  the  transverse  muscles  of  the 
abdomen  attached  to  them,  and  its  point  is  connected  with 
the  linea  alba. 

The  sternum,  as  a  whole,  has  its  anterior  surface  flat,  or 
a  little  convex — is  covered  by  the  aponeurosis  of  the  pecto- 
ral muscles — has  the  tendons  of  the  sterno  mastoid  muscles 
attached  to  its  superior  portion,  and  is  crossed  by  trans- 
verse lines,  marking  its  original  divisions  into  as  many  as 
six  pieces. 

Its  posterior  surface  is  smooth,  somewhat  concave,  and 
covered  by  a  shining  periosteum.  It  also  presents  trans- 
verse lines,  though  not  so  distinct  as  those  in  front.  The 
structure  of  the  sternum  is  spongy,  covered  by  a  thin  com- 
pact layer.  Its  development  is  from  a  number  of  points 
varying  from  six  to  fourteen,  which  do  not  unite  till  late 
in  life.  The  osseous  centres  for  the  first  bone  of  the  ster- 
num are  one  or  two  in  number,  and  make  their  appearance 
during  the  fifth  and  sixth  months — those  of  the  second  and 
third  soon  after — and  the  fourth  at  the  close  of  foetal  life  or 
shortly  after  birth.  Ossification  of  the  ensiform  cartilage 
varies  from  the  second  to  the  eighteenth  year.  The  several 
pieces  of  the  sternum  commence  uniting  from  below  up- 
ward. The  fourth  and  third  are  seen  to  join^ about  puberty, 
the  third  and  second  between  twenty  and  twenty-five,  and 
the  second  and  first  between  twenty-five  and  thirty  years. 


THE  RIBS. 


463 


The  ensiform  cartilage  does  not  join  the  sternum  till  late 
in  life,  about  forty  or  fifty  years.  It  articulates  with  sixteen 
bones,  the  two  clavicles  and  seven  true  ribs  on  each  side. 

THE  KIBS,   (COSm) 

The  ribs  are  twenty-four  in  number,  twelve  on  each  side, 
and  are  divided  into  the  true  and  false.  The  true  are  seven 
in  number,  extend  from  the  vertebra?  to  the  sternum,  and 
are  called  vertebro-sternal.  The  false  extend  from  the  ver- 
tebras to  the  ribs,  and  are  called  the  vertebro-costal  or  aster- 
nal. The  two  last  having  their  extremities  free,  are  called 
FIG.  138.  floating  ribs, 

and  are  the 
shortest.  The 
ribs  present  an 
arched  form, 
and  run  ob- 
liquely down- 
ward and  for- 
ward from  the 

vertebrae  towards  the  sternum.  They  increase  successively 
in  length  from  the  first  to  the  eighth,  and  then  diminish  to 
the  last.  The  breadth  diminishes  gradually  from  the  first 
to  the  twelfth. 

Common  characters  of  the  Eibs. — Each  rib  consists  of  two 
extremities,  a  vertebral  and  sternal,  two  surfaces,  external 
and  internal,  and  two  margins,  superior  and  inferior.  The 
vertebral  extremity  or  posterior  end  has  a  head,  neck,  and 
tubercle.  The  head  is  divided  by  a  middle  ridge  into  two 
articular  faces,  which  are  received  into  corresponding  pits 
on  two  contiguous  vertebrae,  the  edge  between  them  sinking 
into  the  intervertebral  substance.  To  the  ridge  the  inter- 
articular  ligament  is  attached.  The  neck  is  the  contracted, 
round,  and  thick  portion  upon  which  the  head  rests.  It  is 
situated  before  the  transverse  process,  to  which  it  is  attached 
f ,.«-, 

FIG.  138,  A  represents  the  upper  surface,  B  the  lower  surface  of  a  rib. 
«  Head  of  rib.  &  Tubercle,  c  Anterior  end  for  costal  cartilage,  d  Groove 
for  artery  and  nerve,  e  Angle  of  rib. 


\ 


464  THE  RIBS. 

by  the  middle  costo-trans verse  ligament.  Its  upper  border 
has  a  ridge  for  the  attachment  of  the  anterior  or  internal 
cos  to-transverse  ligament.  The  tubercle  is  external  to  the 
neck,  and  seen  on  the  posterior  under  surface  of  the  rib, 
about  an  inch  from  the  head.  It  consists  of  two  portions, 
an  internal  and  external.  The  former  is  smooth,  and  articu- 
lates with  the  transverse  process,  the  latter  gives  attach- 
ment to  the  external  costo-iransverse  ligament.  On  the  out- 
side of  the  tubercle  the  rib  makes  a  turn  which  is  called  its 
angle.  To  this  the  tendon  of  the  sacro  lumbalis  muscle  is 
connected.  This  angle  increases  in  distance  from  the  tuber- 
cle, from  the  first  rib  downward  to  the  last,  where  it  is  not 
so  distinct.  The  anterior  or  sternal  extremity  is  hollow 
for  the  reception  of  the  cartilage.  Beyond  or  external  to 
the  angle,  is  the  body  or  shaft  of  the  rib.  Its  external  sur- 
face is  convex  and  smooth,  and  gives  attachment  to  various 
muscles.  Its  internal  surface  is  concave  and  lined  by  the 
pleura.  Its  superior  margin  is  smooth  and  round,  and  gives 
attachment  to  the  intercostal  muscles.  The  inferior  is  thin 
and  sharp,  and  has  its  inner  side  grooved,  to  lodge  the  in- 
tercostal vessels  and  nerves,  and  for  the  attachment  of  the 
intercostal  muscles. 

Characters  peculiar  to  some  of  the  ribs. — The  first  is  the 
shortest — it  is  flat,  strong  and  broad — has  its  surfaces  pre- 
FIG.  139.  senting  upward  and  down- 

ward, instead  of  forward 
and  backward,  has  no  angle 
and  is  not  twisted.  Its  head 
has  but  one  articular  sur- 
face, and  is  not  divided. 
There  is  no  groove  on  the 
inferior  or  rather  posterior 
edge.  On  the  central  part  of  the  upper  surface  there  is  a 
broad  and  shallow  fossa  for  the  subclavian  artery.  In  front 
of  this  is  a  slight  eminence  for  the  scale nus  anticus  muscle. 

Fio.  139  represents  the  upper  surface  of  the  first  Rib.  a  Head.  6  Tuber- 
cle, c  Anterior  surface,  d  Groove  for  subclavian  artery.  «  Groove  for  subcla- 
vian vein.  /  Anterior  extremity  for  cartilage,  g  Tubercle  for  scalenui  anticus. 


CABTILAGES  OP  THE  BIBS.  465 

The  second  rib  in  some  measure  resembles  the  first  in  hav- 
ing little  or  no  angle  or  twisting,  and  partly  presenting 
upward.  The  tenth  rib  has  but  a  single  articular  surface. 
The  eleventh  and  twelfth  have  likewise  but  one  articular 
face,  have  no  neck,  angle  nor  tuberosity,  and  are  pointed  at 
their  extremity. 

The  ribs  are  spongy,  with  a  thin  covering  of  compact 
matter.  Their  development  is  from  three  points  of  ossifica- 
tion— one  for  the  body,  one  for  the  head,  and  one  for  the 
tuberosity.  Ossification  begins  in  the  body  of  the  rib 
sooner  than  in  the  vertebras.  In  the  epiphysis  it  begins 
between  the  sixteenth  and  twentieth  years ;  and  complete 
union  of  all  the  parts  takes  place  about  the  twenty-fifth 
year.  Each  rib  articulates  by  its  head,  with  two  contigu- 
ous vertebra3,  except  the  first  and  the  last,  which  articulate 
each  with  a  single  vertebra ;  each  unites  also,  by  its  ster- 
nal end,  with  the  costal  cartilage. 

Cartilages  of  the  Ribs. — The  costal  cartilages  are  of  the 
permanent  class,  and  are  regarded  as  part  of  the  skeleton 
of  the  chest.  They  are  situated  at  the  anterior  extremities 
of  the  ribs,  the  seven  uppermost  of  which  they  connect 
with  the  sternum.  The  first  is  short — the  rest  increase 
successively  in  length,  to  the  seventh ;  and  from  this  to  the 
last  they  diminish,  so  that  the  twelfth  has  merely  a  tip  of 
cartilage.  The  costal  extremity  of  each  cartilage  is  broader 
than  the  sternal.  The  depression  in  the  end  of  the  rib 
receives  the  former,  while  the  cavities  along  the  sides  of 
the  sternum,  receive  the  latter.  Their  anterior  surface  is 
convex,  and  gives  origin  to  the  great  pectoral  muscle.  The 
posterior  is  concave  and  lined  partly  by  the  pleura.  Their 
margins,  like  the  ribs,  bound  the  intercostal  spaces,  and 
give  attachment  to  the  internal  intercostals.  The  first  cos- 
tal cartilage  is  short,  broad,  and  descends  obliquely  down- 
ward in  the  direction  of  the  first  rib;  the  second  and  third 
are  nearly  horizontal;  the  rest  ascend  more  and  more.  The 
three  superior  cartilages  of  the  false  ribs  are  blended  the 
one  with  the  other,  and  the  two  lower,  as  already  stated, 
are  free  and  floating. 
30 


466  LIGAMENTS  OF  THE  CHEST. 

These  cartilages  are  the  longest  in  the  body ;  they  are, 
in  middle  life,  white,  flexible,  and  extremely  elastic.  In  old 
age  they  are  much  disposed  to  ossify,  the  costal  being 
more  subject  to  this  change  than  the  sternal  end.  When 
this  occurs  they  become  opaque,  and  assume  a  similar  or- 
ganization with  the  ribs.  The  costal  cartilages  contain  no 
vessels  or  nerves,  but  are  covered  by  a  vascular,  fibrous 
membrane,  called  the  perichondrium. 

LIGAMENTS  OP  THE  CHEST. 

The  ribs  are  articulated  behind  to  the  vertebrae,  and  in 
front  to  the  sternum. 

The  vertebral  articulation  takes  place  at  two  points  of 
the  posterior  extremity  of  the  rib,  viz:  at  its  head,  and  at 
the  neck  and  transverse  process. 

The  head  has  the  capsular  and  the  inter-articular  liga- 
ment, and  two  synovial  membranes. 

The  capsular,  anterior,  stellate,  or  radiating  ligament  (Fig. 
132)  arises  from  the  front  margin  of  the  head  of  the  rib, 
and  radiates  by  three  short  bands  of  ligamentous  fibres,  the 
superior  of  which  to  the  vertebra  above — the  middle  to  the 
intervertebral  substance,  and  the  inferior  to  the  vertebra 
below.  These  bands  are  so  connected  as  to  form  an  imperfect 
capsule,  hence  one  of  the  names  of  this  ligament,  capsular. 

The  intervertebral  ligament  is  attached  to  the  ridge  divi- 
ding the  articular  surfaces  on  the  head  of  the  rib,  and  goes 
to  be  inserted  into  the  intervertebral  substance.  This  lig- 
ament is  short,  strong,  and  somewhat  yellow,  and  also 
separates  the  two  synovial  membranes  which  belong  to  the 
head  of  each  rib,  except  the  first,  eleventh,  and  twelfth. 

Internal  or  anterior  cos to-trans verse  ligament,  (Fig.  140.) 
This  ligament  arises  narrow  from  the  lower  margin  of  the 
transverse  process,  and  has  a  broad  insertion  upon  the  crest 
of  the  upper  edge  of  the  neck  of  the  rib  below. 

External  costo-transverse  or  posterior  ligament,  (Fig.  140,) 
arises  from  the  extremity  of  the  transverse  process,  and  pro- 
ceeds externally  to  be  inserted  into  the  non-articular  portion 
of  the  tubercle  of  the  rib.  It  is  a  short,  flat  plane  of  fibres. 


LIGAMENTS  OF  THE  CHEST. 


467 


-The  ligaments  con- 

FIG.  141. 


The  middle  costo-transverse  ligament  is  situated  behind  the 

neck  of  the  rib,  and  between  it  and  Flo<  ^Q. 

the  front  part  of  the  corresponding 

transverse  process.     It  is  a  short, 

strong  ligament,  which  can  only 

be  seen  by  separating  the  bones, 

or  making  a  horizontal  section  of 

them. 

These  ligaments  firmly  connect 

the  ribs  and  vertebras  together,  and 

also  allow  the  ribs  the  necessary 

freedom  of  motion  in  the  upward, 

downward,  and   slightly  forward 

and  backward  directions. 

The  sternal  articulation  of  the  fiibs.- 

necting  the  costal  cartilages 

with  the  ribs  and  sternum  are 

the  anterior  and. posterior,  the 
superior  and  inferior  costo- 

sternal  ligaments.  The  ster- 
nal ends  of  the  ribs  are  hollow 
and  receive  the  convex  ends 
of  the  cartilages  by  a  species 
of  union  somewhat  resem- 
bling gomphosis. 

The  anterior  costo-sternal  ligament  arises  from  the  costal 
cartilage  and  consists  of  a  thin  layer  of  ligamentous  fibres 
which  radiate  over  the  front  of  the  sternum  and  intermix 
with  those  of  the  opposite  side,  and  with  the  fibres  forming 
the  tendon  of  the  pectoralis  major  muscle. 

The  posterior  costo-sternal  ligament  has  the  same  ra- 
diated arrangement  of  its  fibres  as  the  anterior,  is  smaller 

FIG.  140  represents  the  Ligaments  at  the  vertebral  end  of  the  ribs,  a  a  Lig- 
aments of  the  spinous  processes.  6  6  b  Yellow  ligaments,  c  Anterior  or  internal 
costo-transverse  ligament,  d  Posterior  or  external  costo-transverse  ligament. 

FIG.  141  represents  the  Ligaments  about  the  Sternum  and  Ribs.  1  Capsular 
ligament  of  the  sterno  clavicular  articulation.  2  Interclavicular  ligament. 
3  Rhomboid  or  costo  clavicular  ligament.  4  Interarticular  cartilage,  5  An- 
terior costo  sternal  ligaments  of  the  first  and  second  ribs. 


468         GENERAL  REMARKS  UPON  THE  CHEST. 

and  situated  on  the  posterior  surface  of  the  articula- 
tion. 

The  superior  and  inferior  costo-sternal  ligaments  are  simply 
narrow  fasciculi  of  fibres,  connecting  the  upper  and  lower 
margins  of  the  sternal  end  of  the  costal  cartilages  with  the 
sides  of  the  sternum. 

The  cartilage  of  the  first  rib,  it  seems,  has  no  synovial 
membrane,  and  is  continuous  with  that  of  the  sternum. 
The  cartilage  of  the  second  rib,  at  its  junction  with  the 
sternum,  like  the  heads  of  the  ribs,  is  divided  by  a  liga- 
mentous  partition,  forming  two  cavities  and  two  synovial 
membranes.  The  sixth,  seventh,  and  eighth,  and  occasion- 
ally the  fifth  and  ninth,  have  articulations  with  each  other 
lined  by  a  synovial  membrane.  External  and  internal  liga- 
mentous  fibres  pass  from  one  to  the  other.  Ligamentous 
fibres  are  seen  passing  from  the  cartilage  of  the  seventh 
rib  near  the  sternum,  and  spreading  themselves  over  the 
anterior  surface  of  the  xiphoid  ligament,  and  are  named 
costo-xiphoid  ligaments.  The  motion  of  the  ribs  at  the 
sternum  is  very  limited. 

GENERAL  REMARKS  UPON  THE  CHEST. 

The  Chest  thus  composed  of  the  sternum,  ribs,  costal  car- 
tilages, and  dorsal  vertebras,  all  bound  together  by  the 
ligaments,  presents  a  large  and  very  important  cavity  for 
containing  the  lungs,  the  organs  of  respiration,  and  the 
heart,  the  chief  agent  of  circulation. 

This  cavity,  which  in  the  skeleton  is  continuous  with  the 
abdominal,  in  the  fresh  subject  is  separated  from  the  latter 
by  the  diaphragm.  When  the  arms  are  detached  from  the 
trunk  it  presents  the  form  of  a  truncated  cone,  having 
the  apex  above  and  the  base  below,  flattened  before  and 
behind,  and  convex  at  the  sides.  This  form  of  the  chest, 
however,  may  be  materially  altered  by  tight  lacing,  and 
by  disease.  The  anterior  wall  is,  as  already  stated,  shorter 
and  more  oblique  than  the  posterior,  which  is  vertical.  Its 
surface  is  rendered  very  irregular  by  grooves,  processes,  and 
angles.  The  intercostal  spaces  are  wider  in  front  than 


GENERAL  REMARKS  UPON  THE  CHEST.  469 

behind.  The  superior  opening  of  the  chest  presents  ob- 
liquely downward  and  forward,  and  is  oval,  its  lateral 
diameter  being  the  greatest.  It  gives  passage  to  th-3 
trachea,  oesophagus,  vessels,  nerves,  muscles,  cellular  tis- 
sue, &c.  The  base  of  this  cavity  is  represented  by  the  dia- 
phragm, the  circumference  of  which  is  bounded  by  the 
xiphoid  cartilage,  the  inferior  margin  of  the  cartilages  of 
the  false  ribs,  and  the  lower  dorsal  vertebrae. 

The  dimensions  of  the  thoracic  cavity  vary  according  to 
age  and  in  different  individuals,  and  in  the  same  individual 
according  to  the  state  of  the  diaphragm,  whether  ascending, 
descending,  or  quiescent.  The  capacity  of  the  chest  is 
intermediate  between  that  of  the  abdominal  and  cranial 
cavity.  Its  diameters  are  three,  the  antero-posterior,  trans- 
verse, and  vertical.  The  antero-posterior  has  the  greatest 
length  below,  and  is  shorter  at  either  end  than  on  the 
middle  line,  in  consequence  of  the  projection  forward  of 
the  bodies  of  the  vertebrae.  The  transverse  is  longest  across 
the  eighth  ribs.  The  vertical  has  the  greatest  length  of  the 
three,  and  is  longer  at  the  sides  than  the  middle,  in  conse- 
quence of  the  descent  of  the  diaphragm. 

During  inspiration  all  these,  diameters  are  increased 
and  the  capacity  of  the  chest  enlarged  in  every  direction, 
by  the  elevation  of  the  ribs  and  the  fall  of  the  diaphragm. 
In  expiration,  on  the  contrary,  these  diameters  are  all  less- 
ened by  the  falling  of  the  ribs  and  the  ascent  of  the  dia- 
phragm, and  the  expulsion  of  air  from  the  chest. 

In  the  foatus  these  motions  do  not,  of  course,  take  place, 
and  the  form  of  the  chest  is  very  different  from  that  of  the 
adult.  The  thoracic  cavity  is  short,  its  sides  compressed,  and 
its  base  very  broad,  in  consequence  of  the  collapsed  state  of 
the  lungs,  and  the  great  size  of  the  liver. 

The  antero-posterior  diameter  is  large,  to  provide  for  the 
heart  and  thymus  gland,  while  on  the  sides  it  is  compara- 
tively small,  on  account  of  the  unexpanded  condition  of  the 
lungs.  The  vertical  diameter  is  less,  the  ribs  are  closer 
together,  and  the  intercostal  spaces  shorter.  So  soon,  how- 
ever, as  respiration  begins,  the  chest  expands,  and  all  the 
peculiarities  just  mentioned  are  lost. 


470 


THE  PELVIS. 


SECTION  III. 
THE  PELVIS. 

The  pelvis  is  situated  at  the  lower  portion  of  the  trunk, 
and  is  composed  of  four  bones — the  sacrum,  coccyx,  and 
two  ossa  innominata.  The  two  former  have  been  examined 
along  with  the  spine.  It  only  remains,  therefore,  to  speak 
of  the  latter. 

Os-innominatum. — This  bone  is  situated  at  the  lateral 
and  anterior  portions  of  the  pelvis,  and  in  the  adult  is 
A          FIG.  142.  B  composed  of  a  sin- 

gle piece ;  but  in 
the  young  subject 
consists  of  three : 
the  ilium,  iscliium, 
and  pubis. 

The  ilium  is  sit- 
uated at  the  su- 
perior and  outer 
portion  of  the  pel- 
vis, and  is  the 
largest  of  the 
three  bones  composing  the  innominatum.  This  bone  is  com- 
monly called  the  hip,  or  haunch  bone.  It  is  somewhat  triangu- 
lar, broad  and  flat.  It  is  divided  into  a  body,  ala,  and.  pro- 
cesses. The  body  is  the  lower  narrow  portion,  forming  the 
upper  and  outer  part  of  the  acetabulum.  It  has,  anteriorly,  a 

FIG.  142,  A  represents  an  exterior  view  of  the  Os-innominatum.  1  Crest 
of  Ilium.  2  Anterior  superior  spinous  process.  4  Anterior  inferior  spi- 
nous  process.  5  Notch  for  the  psoas-magnus,  and  iliacus  internus.  6  Ileo- 
pubic  spine.  8  Obturator  foramen.  9  Angle  of  pubis.  11  Descending  ramus 
of  pubis.  12  Tuberosity  of  ischium.  13  Lesser  sciatic  notch.  14  Spine  of 
the  ischium.  15  16  Greater  sciatic  notch.  17  Posterior  inferior  spinous  pro- 
cesses of  ilium.  18  Rough  surface.  19  Posterior  superior  spinous  process. 
21  Dorsum  of  the  ilium. 

FIG.  142,  B  represents  an  inner  view  of  the  innominatum.  The  figures  2  4 
8  9  11  12  13  14  16  correspond  to  similar  points  as  in  Fig.  A.  3  Groove  for 
obturator  vessels  and  nerves.  20  Posterior  superior  spinous  process.  23 
Posterior  inferior  spinous  process.  22  Fissure  between  posterior  processes. 
21  Venter  of  ilium.  24  Svmphysis  pubis. 


THE  PELVIS.  471 

rough,  triangular  surface,  for  articulating  with  the  pubis ; 
and  inferiorly  and  posteriorly,  another  for  articulating 
with  the  ischium. 

The  ala  is  the  broad  portion  which  expands  upward  and 
outward  from  the  body;  it  has  two  surfaces  and  a  circum- 
ference. Its  external  surface  is  rough,  and  irregularly  con- 
vex and  concave,  and  is  called  the  dorsum.  This  surface 
has  two  semicircular  lines — a  superior  and  inferior.  The 
superior  is  long,  usually  well  marked,  begins  a  short  dis- 
tance behind  the  anterior  superior  spinous  process,  and 
takes  a  curved  direction  backward  to  the  posterior  part  of 
the  great  sciatic  notch.  To  this  line,  and  all  that  part  of 
the  dorsum  above,  and  between  it  and  the  upper  edge  of 
the  ilium,  with  the  exception  of  a  small  posterior  portion, 
the  gluteus  medim  muscle  is  attached.  This  excepted  pos- 
terior part  gives  attachment  to  the  gluteus  maximus.  The 
inferior  line,  a  short  distance  above  the  acetabulum,  curves 
backward  from  the  anterior  inferior  spinous  process  to  the 
fore  part  of  the  sciatic  notch.  To  this  line,  and  to  the 
space  between  it  and  the  superior  line,  the  gluteus  minimus 
muscle  is  attached.  Below  the  inferior  line,  the  body  be- 
comes prominent,  and  gives  attachment  to  a  part  of  the 
gluteus  minimus — the  external  tendon  of  the  rectus/emorts 
muscle,  and  a  portion  of  the  capsular  ligament. 

The  internal  surface  of  the  ilium,  called  the  venter,  has  its 
central  and  superior  part  very  concave  for  lodging  the 
iliacus  internus  muscle ;  there  is  also  seen  upon  it  an  ob- 
lique canal  for  the  nutritious  artery.  Below  the  venter 
there  is  a  rounded  edge  which  is  continuous  with  one  from 
the  promontory  of  the  sacrum  behind,  and  the  pubis  before, 
called  the  linea-ileo  pectinea.  All  the  surface  above  thia 
line  enters  into  the  false  pelvis.  The  small  surface  below 
it,  and  above  the  sciatic  notch,  helps  to  form  the  true 
pelvis. 

The  posterior  part  of  this  internal  surface,  is  rough,  and 
divided  into  two  portions :  the  anterior,  covered  with  car- 
tilage, and  articulating  with  the  sacrum;  and  the  posterior, 
rough  for  the  attachment  of  the  sacro  sciatic-ligaments. 


472  THE  PELVIS. 

The  processes  of  the  ilium  are  seen  upon  its  circumference. 
Its  superior  border  is  called  the  crest  In  the  young  sub- 
ject this  is  an  epiphysis,  and  presents  the  form  of  an  italic 
8,  looking  inward  in  front,  and  outward  behind.  The 
anterior  extremity  of  the  crest  presents  a  projection  called 
the  anterior  superior  spinous  process,  which  gives  origin  to 
the  sartorius  and  tensor  vaginw  femoris  muscles,  and  Pou- 
part's  ligament. 

The  posterior  extremity  of  the  crest  is  the  posterior  supe- 
rior spinous  process,  to  which  the  sciatic  ligaments  are 
attached.  The  crest  also  has  an  inner  margin,  from  which 
arises  the  trans versalis  abdominis  muscle,  an  outer  margin 
for  the  attachment  of  the  external  oblique,  and  an  interme- 
diate space  for  the  internal  oblique.  The  anterior  circum- 
ference of  the  ilium  presents  a  notch  bounded  above  by  the 
anterior  superior  spine,  and  below  by  the  anterior  inferior 
spine.  This  latter  is  above  the  outer  part  of  the  acetabulum 
and  gives  origin  to  the  rectus  femoris  muscle.  The  notch 
has  the  gluteus  medius  attached  to  it,  and  an  external  cu- 
taneous nerve  occupying  it.  Below  and  internal  to  the  an- 
terior inferior  spinous  process,  is  a  hollow,  along  which  pass 
fhepsoas  magnus  and  iliacus  internus  muscles;  internal  to 
this  hollow  and  where  the  ilium  unites  with  the  pubis,  is 
a  prominence  called  the  ilio-pectineal  eminence.  The  poste- 
rior circumference,  in  addition  to  the  posterior  superior 
spinous  process,  has  about  an  inch  and  a  quarter  below  the 
posterior  inferior  spinous  process.  Below  this  spine  the 
ilium  becomes  notched  to  form  the  sciatic  notch. 

The  ischium  (Fig.  142)  is  the  next  in  size  of  the  bones  of 
the  innominatum,  and  is  situated  at  the  lateral  and  inferior 
part  of  the  pelvis.  It  is  the  bone  on  which  we  sit.  It  con- 
sists of  a  body  and  processes.  The  body  presents  a  trian- 
gular or  pyramidal  form,  and  has  three  surfaces,  an  inter- 
nal, posterior,  and  external.  The  internal  surface,  called  the 
plane  of  the  ischium,  is  smooth,  broad  above  and  narrow 
below.  The  posterior  forms  a  prominent  rounded  surface, 
corresponding  to  the  posterior  parietes  of  the  acetabulum. 
The  external  surface  is  much  excavated  and  forms  the  lower 


THE  PELVIS.  473 

and  outer  part  of  the  acetabulum.  At  this  point  the  body 
contracts  and  presents  a  groove  bounded  above  by  the  coty- 
loid  ridge,  along  which  the  tendon  of  the  obturator  externus 
muscle  passes.  At  the  posterior  part  of  the  neck,  just  below 
the  sciatic  notch,  is  seen  the  spinous  process  which  projects 
inward  and  backward,  and  to  which  is  attached  the  superior 
gemellus  muscle  and  the  lesser  sciatic  ligament.  Below  this 
spine  is  a  smooth  pulley-like  surface,  round  which  turns  the 
tendon  of  the  obturator  internus.  As  we  descend,  the  next 
process  is  rough  and  large,  and  called  the  tuberosity — it  is 
covered  with  cartilage,  and  presents  three  faces,  one  an- 
terior, which  gives  origin  to  the  semi-membranosus  muscle; 
and  two  posterior,  from  which  the  semitendinosus  and  bi- 
ceps arise.  To  the  outer  margin,  the  adductor  magnus, 
quadratus  femoris ,  and  gemellus  inferior  are  attached ;  to  the 
inner,  the  long  sacro-sciatic  ligament.  Between  the  spine 
and  the  tuberosity  is  the  lesser  sciatic  notch,  converted  into 
a  foramen  by  the  long  sciatic  ligament.  From  the  tuber- 
osity the  ramus  ascends  forward  and  inward  to  unite  with 
the  pubis,  and  bounds  the  inferior  and  internal  portion  of 
the  thyroid  foramen.  It  is  a  flat  process,  its  surfaces  pre- 
senting, externally  and  internally.  Its  anterior  border 
bounds,  in  part,  the  lower  outlet  of  the  pelvis. 

The  os-pubis  (Fig.  142)  is  smaller  than  either  the  ilium 
or  ischium,  and  is  situated  at  the  front  part  of  the  pelvis ; 
it  consists  also  of  a  body  and  processes.  The  most  external 
portion  is  regarded  as  the  body;  it  is  thick,  and  forms  the 
internal  and  upper  part  of  the  acetabulum.  Its  lower  por- 
tion unites  with  the  body  of  the  ischium ;  its  upper  joins 
the  ilium  in  the  ilio-pectineal  eminence.  Its  inner  surface 
is  smooth,  and  enters  into  the  formation  of  the  anterior 
pelvic  wall.  From  the  body  proceeds,  transversely  inward 
and  forward,  a  process  called  the  horizontal  ramus.  The 
superior  surface  of  this  ramus  is  smooth,  and  bounded  in- 
ternally by  a  process  or  tuberosity,  called  the  spine  of  the 
pubis,  which  gives  insertion  to  Poupart's  ligament.  From 
this  spine  proceed  outward  two  ridges;  the  posterior  is 
the  more  elevated  and  frequently  sharp,  called  the  crista} 


THE  PELVIS. 

and  forms  the  anterior  portion  of  the  linea  ilio-pectinea,  to 
which  is  attached  G-imbernat's  ligament  and  the  fascia 
lata.  The  anterior  ridge  is  more  round,  and  ends  at  the 
upper  margin  of  the  acetabulum.  Between  the  two  ridges 
is  situated  the  pectineus  muscle.  Internal  to  the  spine  of 
the  pubis  is  the  crest,  leading  transversely  to  the  median 
line,  and  about  an  inch  in  length.  It  gives  attachment  to 
the  rectus  abdominis  and  pyramidalis  muscles,  and  to  the 
united  tendons  of  the  internal  oblique  and  trans versalis. 
From  the  crest  there  is  an  inferior  or  descending  portion 
called  the  sympJiysis  and  descending  ramus.  The  symphysis 
is  vertical  and  rough,  and  forms  with  the  crest  the  angle  of 
the  pubis.  It  meets  its  fellow  of  the  opposite  side  by  an  in- 
termediate substance  of  fibre-cartilage.  The  ramus  goes 
backward  and  outward  to  meet  the  ramus  of  the  ischium, 
and  its  outer  edge  bounds  the  thyroid  foramen,  while  its 
inner  edge  gives  attachment  to  the  crus  of  the  penis  or  the 
clitoris.  The  space  between  the  rami  on  either  side  and 
below  the  symphysis  describes  a  curve  called  the  arch  of 
the  pubis. 

The  innominatum,  composed  of  three  bones,  presents  at 
their  common  point  of  junction  a  deep,  hemispherical  cavity, 
the  acetabulum  or  cotyloid  cavity.  The  ilium  forms  a  little 
less  than  two-fifths,  the  ischium  a  little  more  than  two- 
fifths,  and  the  pubis  about  one-fifth  of  this  cavity.  It  is 
bounded  by  a  deep  notch  internally,  which  is  converted,  by 
a  ligament  stretched  across  from  the  pubis  to  the  ischium, 
into  a  foramen,  through  which  pass  the  articular  vessels. 
The  superior  and  outer  part  of  this  cavity  is  smooth,  cov- 
ered with  cartilage,  and  receives  the  head  of  the  thigh  bone. 
The  central  portion  and  the  part  leading  from  it  to  the 
notch,  is  rough,  gives  attachment  to  the  ligamentum  teres, 
and  contains  a  quantity  of  soft  adipose  matter. 

In  the  front  of  the  innominatum  and  to  the  inside  of  each 
acetabulum  are  seen  two  large  foramina,  called  the  obturator 
or  thyroid.  These  are  formed  by  the  ischium  and  pubis. 
The  edge  of  this  opening  is  thin  and  has  superiorly  a 
groove  for  the  passage  of  the  obturator  vessels  and  nerve. 


LIGAMENTS   OF  THE  PELVIS.  475 

The  rest  of  the  opening  is  filled  "by  the  obturator  liga- 
ment. 

The  structure  of  the  innominatum  is  cellular  internally, 
with  a  compact  layer  externally. 

Its  development  is  from  three  principal  centres  of  ossifica- 
tion, one  for  the  ilium,  one  for  the  ischium,  and  one  for  the 
puhis,  all  of  which  meet  in  the  acetabulum ;  and  five  addi- 
tional or  secondary  points  are  noticed,  one  for  the  crest  of 
the  ilium,  one  for  the  tuherosity  of  the  ischium,  one  for  the 
anterior  and  inferior  spine  of  the  ilium,  one  for  the  angle 
of  the  pubis,  and  one  for  the  centre  of  the  acetabulum. 
These  latter  points  appear  at  the  twelfth  year.  Ossifica- 
tion is  noticed  first  in  the  ilium,  at  the  same  time  or  soon 
after  it  occurs  in  the  vertebrae  ;  about  the  third  month  in 
the  ischium,  and  between  the  fourth  and  fifth  months  in 
the  pubis,  about  the  sixth  year  the  rami  of  the  ischium  and 
pubis  are  found  nearly  ossified,  and  join  in  the  tenth  year. 
The  three  bones  are  complete  in  the  acetabulum  by  the 
twenty-fifth  year. 

The  osinnominatum  articulates  with  its  fellow,  the 
sacrum  and  the  head  of  the  femur. 

LIGAMENTS  OF  THE  PELVIS. 

The  mode  of  articulation  Iretween  the  last  lumbar  verte- 
bra and  the  sacrum,  is  the  same  as  those  of  the  other  ver- 
tebrae already  described;  by  the  inter  vertebral,  anterior  and 
posterior,  capsular,  yellow,  supra  spinous,  and  interspinous 
ligaments,  and  synovial  membranes.  There  is  however  an 
additional  ligament,  consisting  of  a  short,  thick,  strong  fas- 
ciculus extending  from  the  transverse  process  of  the  last 
lumbar  vertebra  to  the  posterior  superior  part  of  the  base 
of  the  sacrum,  called  lumbo-sacral  ligament.  The  next  liga- 
ment connecting  the  vertebral  column  to  the  pelvis  is  the 
ilio-lumbar.  It  arises  from  the  transverse  processes  of  the 
two  lower  lumbar  vertebrae,  and  is  inserted  into  the  poste- 
rior crest  of  the  ilium  and  into  its  posterior  superior  spinous 
process.  The  ligaments  of  the  pelvis  are  those  connecting 
the  sacrum  and  ilium,  those  connecting  the  sacrum,  coc- 


476 


LIGAMENTS   OF  THE  PELVIS. 


cyx,  and  ischium,  those  binding  the  ossa-pubis  together, 
and  those  uniting  the  sacrum  and  coccyx. 

FIG.  143.  The   sacro-iliac  articulation 

consists  of  anterior  and  poste- 
rior sacro-iliac  ligaments. 

The  anterior  sacro  iliac  liga- 
ment is  a  thin  sheet  of  fibres 
passing  from  the  ilium  to  the 
sacrum  on  the  anterior  surface 
of  the  joint. 

The  posterio  sacro-iliac  liga- 
ment is  much  stronger  than  the 
anterior,  and  forms  the  chief 
bond  of  union  between  the 
sacrum  and  ilium.  It  consists 
of  numerous  strong  ligament- 
ous  fasciculi  extending  transversely  and  obliquely  from 
the  rough  surface  of  the  sacrum  to  the  rough  surface  of 
the  ilium,  and  to  its  posterior  superior  spine.  This  latter 
attachment  receives  the  name  of  sacro-spinous  ligament. 

The  articular  surfaces  of  the  sacrum  and  ilium  are  co- 
vered with  cartilage,  and  have  an  imperfect  synovial  mem- 
brane, more  readily  distinguished  in  the  young  than  in 
the  adult,  and  occasionally  lubricated  with  fluid. 

Sacro-iscliiac  articulation.  The  sacrum  and  coccyx  are 
united  to  the  ischium  by  two  ligaments,  the  anterior  and 
posterior  s  aero-sciatic. 

The  anterior  or  lesser  sacro-sciatic  ligament  arises  broad 
and  thin  from  the  side  of  the  sacrum  and  coccyx,  crosses 
the  other,  and  has  a  narrow  insertion  into  the  spine  of  the 
ischium.  Its  pelvic  portion  is  connected  with  the  coccygeus 
muscle. 

The  posterior  or  great  sacro-sciatic  ligament  is  much  larger, 

FIG.  143  represents  a  front  view  of  the  Ligaments  of  the  Pelvis.  1  Ante- 
rior vertebral  ligament,  its  lower  end.  2  Sacro-vertebral  ligament.  3  Ileo- 
lumbar  ligament.  4  Sacro-iliac  ligament,  its  anterior  portion.  5  Obturator 
ligament.  6  Poupart's  ligament.  7  Gimbernat's  ligament.  8  Capsular  liga- 
ment of  hip-joint.  9  Accessory  ligament  of  hip-joint. 


LIGAMENTS   OF  THE  PELVIS. 


477 


longer  and  thicker  than  the  anterior,  and  arises  from  the 
posterior  inferior  spinous  process  of  the  ilium,  and  the 
side  of  the  sacrum 
and  coccyx.  It  is 
inserted  hy  a  broad 
attachment  into  the 
inner  margin  of  the 
tuberosity  of  the 
ischium,  which  is 
traced  forward  in 
the  shape  of  a  falci- 
form process,  upon 
the  ramus  of  the  is- 
chium, and  serves  to 
shield  the  internal 
pudic  vessels  and  nerves.  Posteriorly,  it  is  covered  by 
the  glutens  maximus  muscle,  to  some  of  the  fibres  of  which 
it  gives  origin.  These  ligaments  are  of  use  in  forming  the 
lower  and  lateral  parietes  of  the  true  pelvis.  By  their 
crossing  they  convert  the  ischiatic  notches  into  foramina, 
the  larger  and  superior  giving  passage  to  the  pyriform 
muscle,  the  gluteal  and  sciatic  vessels  and  nerves,  while  the 
smaller  and  inferior  transmit  the  internal  pudic  vessels 
and  nerve,  and  the  tendon  of  the  obturator  internus  muscle. 
Articulation  of  the  ossa  pubis. — The  two  ossa  pubis  are 
united,  along  the  median  line,  by  an  intermediate  fibro-car- 
tilage.  Its  fibres  assume  the  form  of  concentric  laminaa, 
some  of  which  are  continued  all  round,  while  others  are 
interrupted ;  some  take  the  oblique  course,  and  cross  each 
other.  This  articulation  resembles,  in  some  degree,  the 
intervertebral,  and  sometimes  contains,  in  its  centre,  a 

FIG.  144  represents  a  posterior  view  of  the  Ligaments  of  the  Pelvis.  1  Base 
of  sacrum.  2  Coccyx.  3  3  Crest  of  ilium.  4  4  Tuber  ischii.  5  5  Greater 
sciatic  notch.  6  Lesser  sciatic  notch.  7  Femur.  8  8  Sacro-iliac  ligaments, 
posterior  portion.  9  Sacro-spinous.  10  Posterior-sacro-coccygeal  ligament. 
]1  Obturator  ligament.  12  Obturator  foramen.  13  13  Upper  attachment  of 
the  greater  sacro-sciatic  ligament.  14  Its  lower  attachment.  15  16  The  two 
attachments  of  the  lesser  sciatic  ligament. 


478  GENERAL  REMARKS  UPON  THE  PELVIS. 

pulpy  or  viscid  fluid.  At  its  posterior  portion,  a  delicate 
synovial  membrane  has  occasionally  been  seen. 

The  anterior  pubic  ligament  consists  of  fibres  passing  in 
front  of  the  symphysis,  from  the  one  side  to  the  other. 

The  posterior  pubic  ligament  is  made  up  of  a  few  fibres  on 
the  posterior  surface  of  the  symphysis. 

The  sub-pubic,  or  inter-pubic  ligament,  is  situated  beneath 
the  symphysis  to  which  it  is  connected.  Its  form  is  trian- 
gular, about  half  an  inch  broad,  and  consists  of  a  strong, 
compact  layer  of  fibres,  passing  from  the  crus  of  the  pubis, 
on  the  one  side,  to  a  similar  point  on  the  opposite,  round- 
ing off  the  angle  or  arch  of  the  pubis.  The  triangular 
ligament  of  the  urethra  is  below  this  sub-pubic  ligament. 

The  superior  pubic  ligament  consists  of  a  plane  of  fibres 
uniting  the  angles  of  the  pubis. 

The  obturator  ligament  closes  the  obturator  foramen,  and 
consists  of  a  thin  fibrous  membrane,  which  is  attached  all 
round  to  the  edge  of  this  opening,  except  at  its  superior 
part,  where  the  obturator  vessels  and  nerve  pass.  Its  outer 
and  inner  surfaces  respectively  give  attachment  to  the  ex- 
ternal and  internal  obturator  muscles.  The  articulation  of  the 
sacrum  and  coccyx  has  been  described  under  the  ligaments 
of  the  spine. 

GENERAL  REMARKS  UPON  THE  PELVIS,   AS  A  WHOLE. 

The  pelvis,  as  we  have  seen,  consists  of  the  two  ossa  in- 
nominata,  the  sacrum  and  coccyx.  These  are  divided  on 
the  interior  by  the  linea  ilio-pectinea,  into  the  false  and  the 
true  pelvis.  All  above  this  line,  as  high  as  the  top  of  the 
ilium,  is  the  false  pelvis;  all  below  is  the  true,  and  this  line 
of  separation  between  the  two  is  called  the  superior  strait. 
The  cavity  of  the  pelvis  presents  the  form  of  a  flat  truncated 
cone,  the  base  above,  the  apex  below.  It  contains  some  of 
the  viscera  of  the  abdomen,  while  it  and  its  parietes  receive 
and  support  the  organs  of  generation,  and  part  of  the  uri- 
nary organs,  at  the  same  time  furnishing  attachment  for 
many  muscles. 

The  upper  or  false  pelvis  is  the  base  of  this  cone.    In  the 


GENERAL  REMARKS  UPON  THE  PELVIS.  479 

dry  skeleton  it  is  deficient  in  front,  but  in  the  fresh  subject 
it  is  closed  in  by  the  abdominal  muscles.  The  alas  of  the 
ilia  constitute  its  lateral  and  superior  boundaries. 

The  lower  or  true  pelvis  is  a  perfect  bony  canal,  deeper 
however,  at  the  sides  and  behind,  than  in  front;  the  sacrum 
and  coccyx  forming  its  posterior  wall,  the  ischia  and  part 
of  the  ilia  its  sides,  and  the  pubis  completing  it  in  front. 
The  true  pelvis  has  two  orifices,  an  upper  and  lower,  called 
the  superior  and  inferior  straits,  or  outlets  of  the  pelvis. 
The  superior  strait  looks  forward  and  upward,  and  its  axis 
may  be  represented  by  a  line  drawn  from  the  point  of  the 
coccyx  to  about  an  inch  below  the  umbilicus.  The  inferior 
strait  or  lower  outlet  is  smaller  than  the  upper,  and  in  the 
fresh  subject  is  much  smaller  still,  owing  to  the  closing  of 
the  sciatic  notches,  which  limits  the  opening  to  the  space 
between  the  arch  and  rami  of  the  pubis  and  the  coccyx. 
The  opening  of  the  lower  strait  looks  downward  and  for- 
ward, and  its  axis  is  marked  by  a  line  passing  through  its 
centre  and  striking  the  lower  part  of  the  first  bone  of  the 
sacrum ;  so  that  it  will  be  seen  that  the  perpendiculars  to 
the  planes  of  the  two  straits  have  different  directions,  and 
decussate  or  cross  each  other  about  the  centre  of  the  pelvis, 
forming  an  obtuse  angle  looking  forward.  The  axis  of  the 
pelvis  describes  a  curve,  the  upper  strait  looking  down- 
ward and  backward,  the  lower  strait  downward  and  for- 
ward, important  practical  points  to  recollect  in  parturition 
and  in  the  operation  for  stone. 

DIFFERENCES  BETWEEN  THE  MALE  AND  FEMALE  PELVIS. 

The  female  pelvis  differs  from  the  male  in  several  points. 
It  is  larger,  the  ala3  of  the  ilia  are  wider  apart,  more  ex- 
panded and  not  so  concave ;  the  depth  of  the  pelvis  is  not 
so  great.  The  upper  and  lower  straits  are  both  wider  and 
rounder  ;  the  sacrum  is  shorter,  more  concave,  and  wider ; 
the  promontory  of  the  sacrum  is  less  ;  the  rami  of  the  pubis 
are  farther  apart,  but  not  so  long  as  in  the  male ;  and  the 
arch  of  the  pubis  is  regularly  rounded  and  smooth,  whereas 
in  the  male  it  forms  an  acute  angle.  The  cartilage  at  the 


480  GENERAL  REMARKS  UPON  THE  PELVIS. 

symphysis  pubis  is  thicker  in  the  female,  the  tuberosities  are 
further  apart,  and  the  acetabula  more  distant  from  each 
other.  All  the  bones  of  the  female  pelvis  are  more  delicate, 
rounder,  and  thin ;  and  its  diameters  are  greater  than  those 
of  the  male. 

The  average  diameters  of  the  female  pelvis  are  given  as 
follows — (Fig.  145.)  In  the  superior  strait  there  are  three, 
the  antero-posterior,  transverse,  and  oblique. 

The  first  extends  from  the  middle  of  the  promontory  of 
FIG.  145.  the  sacrum  to  the  superior 

part  of  the  symphysis  pu- 
bis, and  measures  about 
four  inches.  The  second, 
or  transverse,  extends  from 
the  central  part  of  the  su- 
perior strait,  on  the  one 
side,  to  a  similar  point  on 
the  opposite,  and  measures 
about  five  inches.  The  third,  or  oblique  diameter,  measures 
about  four  and  a  half  inches,  and  reaches  from  the  sacro- 
iliac  junction  to  the  opposite  ilio-pectineal  eminence. 

TABLE    OF    MEASUREMENTS    OF    THE    MALE    AND    FEMALE    PELVIS, 
BY    MECKEL. 

MALE.  FEMALE. 

Transverse  diameter  of  great  pelvis  between  anterior  In.  Lines.    In.  Lines. 

and  superior  spinous  processes  of  ilia,  7886 

Distance  between  crista  of  ilia,  8394 

Transverse  diameter  of  superior  strait,  465 

Oblique  diameter  of  superior  strait,  4545 

Transverse  diameter  of  the  cavity,  4  48 

Oblique  diameter  of  the  cavity,  5  54 

Antero-posterior  diameter  of  the  cavity,  5  48 

Transverse  diameter  of  lower  strait,  3  45 

Antero-posterior  diameter  of  lower  strait,  33        44 

This  latter  diameter,  from  the  mobility  of  the  coccyx  in 
the  female,  can  be  increased  to  five  inches. 

FIG.  145  represents  the  average  diameters  of  the  superior  Strait  of  the  fe- 
male Pelvis.  1  3  Oblique  diameters.  2  Transverse.  4  Antero-posterior  or 
sacro-pubic  diameter. 


MUSCLES   OF  ANTERIOR  NECK.  481 

CHAPTER  II. 

ACTIVE  ORGANS    OF    THE    TRUNK. 

FIRST     DIVISION. 
ORGANS  BELONGING  TO  THE  NECK  AND   BACK. 

1.  Organs  of  motion — the  muscles. 

2.  Organ  of  deglutition — oesophagus. 

3.  Organs  of  circulation — blood-vesssls. 

4.  Organs  of  innervation — nerves. 

5.  Thyroid  gland. 

6.  Lymphatic  glands. 
*T.  Fascia  of  the  neck. 
8.  Organ  of  voice. 

SECTION    I. 

ORGANS  OF  MOTION — MUSCLES  OF   ANTERIOR   NECK. 

Dissection. — Make  an  incision  through  the  integuments 
along  the  clavicle,  from  the  sternum  to  the  acrornion  pro- 
cess; a  second  incis-  FIG.  146. 
ion  from  the  chin, 
along   the  margin 
of  the  lower  jaw, 
to  the  mastoid  pro- 
cess ;  connect  these 
two  l>y  a  third,  run- 
ning along  the  me- 
dian   line    of    the 
neck,  frorn  the  chin 
to    the    sternum. 
The     integument, 
thus    marked    off, 
should  be  dissected  from  £he  chin,  obliquely  downward  and 
outward  towards  the  clavicle,  embracing  the  whole  side  of 

FIG.  146  represents  the  superficial  Muscles  of  the  Neck,    a  Platysma  my- 
oides,  or  latissimus  colli.    &  Sterao-cleido  mastoideus.    c  Sternal  attachment. 
d  Clavicular  attachment,    e  Sterno-hyoideus. 
31 


482  MUSCLES  OF  ANTERIOR  ISTECK. 

the  neck.     This  brings  to  view  the  superficial  fascia,  the 
removal  of  which  exposes  the  first  superficial  muscle. 

The  platysma  myoides,  (7tta*uj,  ^vj,  «&>$,  broad  muscle-like 
lamella)  or  latissimus  colli,  consists  of  a  very  delicate,  thin, 
pale,  and  broad  plane  of  muscular  fibres,  situated  between 
two  layers  of  the  superficial  fascia.  It  is  a  cutaneous 
muscle  corresponding  to  the  panniculus  carnosus  of  quad- 
rupeds. 

It  arises  below  the  clavicle  from  the  cellular  tissue  and 
integument  covering  the  pectoral  and  deltoid  muscles,  and 
then  ascends  obliquely  inward  upon  the  side  of  the  neck, 
to  be  inserted  into  the  cellular  tissue  and  skin  of  the  chin, 
where  it  intersects  fibres  from  the  opposite  side,  and  into 
the  fascia  of  the  lower  jaw.  Its  fibres  are  frequently  traced 
upward,  intermingling  with  the  muscles  at  the  angle  of  the 
mouth,  and  backward  to  the  fascia  covering  the  parotid 
gland.  From  this  gland  a  transverse  band  of  fibres,  riso- 
rius  santorini,  have  been  traced  to  the  angles  of  the  mouth. 

Function. — To  depress  the  lower  jaw  and  angles  of  the 
mouth,  and  if  the  mouth  be  closed  to  raise  the  skin  upon 
the  neck.  It  covers  and  supports  the  muscles,  vessels  and 
glands  beneath,  and  has  the  external  jugular  vein  partly 
imbedded  in  its  substance. 

Sterno-cleido  mastoideus  (Fig.  146)  is  situated  at  the  lat- 
eral and  anterior  part  of  the  neck,  enclosed  between  two 
layers  of  the  cervical  fascia.  It  arises  from  the  sternum 
by  a  strong  flat  tendon,  and  from  the  sternal  third  or 
half  of  the  clavicle  by  a  broad,  fleshy  and  aponeurotic  ori- 
gin. These  two  origins  of  this  muscle  include  a  small 
space  of  triangular  shape,  containing  small  vessels  and  cel- 
lular substance.  The  sternal  portion  is  the  larger,  and  as 
it  ascends,  overlaps  the  clavicular  which  proceeds  verti- 
cally. About  tlie  middle  of  the  neck  the  two  are  united, 
and  thence  go  to  be  inserted  into  the  mastoid  process  by  a 
thick,  round  tendon,  and  by  an  aponeurosis  into  the  outer 
portion  of  the  superior  transverse  ridge  of  the  occipital 
bone. 

Function. — Both  muscles  acting  together  will  bend  the 


MUSCLES   OF  ANTERIOR  NECK. 


483 


FIG.  147. 


head  forward.  If  the  sternal  portion  act  alone  it  will  turn 
the  face  to  the  opposite  side  ;  if  the  clavicular  act  by  itself 
it  will  bend  the 
head  to  the  same 
side.  If  the  mus- 
cles of  the  back 
be  in  strong  ac- 
tion, this  muscle 
can  assist  in  still 
further  throwing 
the  head  back- 
ward, as  seen  in 
that  variety  of 
tetanus  called 
opisthotonos.  It 
is  concerned  in 
the  production  of 
wry  neck.  It  has 
in  front  or  cover- 
ing it,  the  skin, 
platysma,  superficial  fascia,  external  jugular  vein,  portion 
of  the  parotid  gland,  branches  of  the  portio-dura,  and  cervi- 
cal plexus  of  nerves,  and  at  its  upper  part  it  is  perforated 
by  the  spinal  accessory  nerve,  which,  however,  sometimes 
passes  behind  it. 

The  sterno-liyoideus  is  a  long,  narrow,  flat  muscle,  sit- 
uated on  either  side  of  the  median  line  of  the  neck,  and 
exposed  by  removing  the  deep  cervical  fascia.  It  arises 
from  the  first  bone  of  the  sternum  on  its  posterior  surface, 
and  the  sternal  end  of  the  clavicle,  ascends  and  is  inserted 
into  the  inferior  margin  of  the  body  of  the  os-hyoides. 

FIG.  147  represents  the  principal  muscles  of  the  neck,  after  turning  aside 
the  platysma  myoides.  a  Mastoid  process.  6  Hyoid  bone,  c  Sterno  hyoideus 
muscle,  d  Sterno  thyroideus.  t  Omo  hyoideus.  /  Origin  of  omo-hyoidens. 
g  Thyroid  gland,  h  Anterior  belly  of  digastricus.  i  Posterior  belly  of  the 
same,  j  Where  the  digastric  tendon  passes  through  the  stylo-hyoideus.  k 
Mylo-hyoideus.  I  Genio-hyoideus.  m  Hyo-glossus.  n  Thyro-hyoideus. 
9  Thyroid  cartilage,  p  Scalenus  anticus.  q  Rectus  capitis-anticus  major, 
r  Levator  anguli  scapula?,  s  Splenius. 


484  MUSCLES  OF  ANTERIOR  NECK. 

Function. — To  draw  down  the  os-liyoides,  pharynx,  and 
larynx.  It  is  covered  by  the  sternum,  clavicle,  and  sterno- 
mastoid  muscle  at  its  lower  portion. 

The  sterno-tliyroideus  is  situated  beneath  the  last,  and  is 
broader  and  shorter,  being  ribbon-like  in  its  appearance. 
It  arises  from  the  back  part  of  the  upper  bone  of  the  ster- 
num and  the  cartilage  of  the  first  rib,  ascends  obliquely, 
and  is  inserted  into  the  ala  of  the  thyroid  cartilage,  upon 
its  oblique  line. 

Function. — To  draw  down  the  larynx.  It  is  covered  by 
the  sterno-hyoid  and  mastoid  muscles. 

The  omo-liyoideus  (w^oj,  shoulder^)  is  situated  obliquely 
across  the  neck,  and  is  a  long,  narrow,  and  double-bellied 
muscle.  It  arises  from  the  superior  costa  of  the  scapula, 
posterior  to  its  semi-lunar  notch,  and  from  the  ligament  of 
this  notch  by  a  fleshy  origin.  It  occasionally  arises  from 
the  acromial  end  of  the  clavicle,  and  base  of  the  coracoid 
process.  It  ascends  above  the  clavicle  and  passes  behind  the 
sterno  mastoid  muscle,  where  it  becomes  tendinous.  After 
this  it  again  becomes  fleshy  and  is  inserted  into  the  inferior 
border  of  the  os-hyoides,  at  the  junction  of  its  body  and 
cornu. 

Function. — To  draw  the  os-hyoides  downward  and  back- 
ward, and  assist  in  deglutition.  Its  origin  is  concealed  by 
the  trapezius;  it  crosses  the  carotid  artery  and  internal 
jugular  vein,  and  its  insertion  is  covered  by  the  fascia  and 
integuments. 

The  two  sterno-mastoid  muscles,  with  the  omo-liyoid,  and 
the  anterior  edge  of  the  trapezius,  to  be  presently  noticed, 
form  several  triangles  very  important  in  a  surgical  point 
of  view,  and  recognizable  in  the  living  subject. 

The  two  sterno-mastoid  muscles,  coming  together  at  the 
sternum,  form  the  apex  of  a  large  triangular  space  on  the 
front  of  the  neck,  the  sides  of  which  are  formed  by  the  diver- 
gence of  these  same  muscles,  to  the  mastoid  processes,  while 
the  base  of  this  triangle  is  above,  and  constituted  by  the 
lower  jaw.  The  median  line  of  the  neck  divides  this  triangle 
into  two,  called  the  anterior  lateral  triangles  of  the  neck. 


TRIANGLES  OF   THE   NECK.  485 

On  the  outside  of  the  mastoid  muscle,  and  between  its 
posterior  edge  and  the  anterior  edge  of  the  trapezius,  there 
is  another  triangular  space,  having  its  base  below,  resting 
on  the  clavicle — its  apex  above,  at  the  mastoid  process, 
where  the  muscles  meet,  while  its  sides  are  formed  by  the 
same  muscles.  This  space  is  called  the  posterior  lateral 
triangle  of  the  neck. 

Each  of  these  large  triangular  spaces  is  crossed  by  the 
omo-hyoideus  muscle,  which  divides  each  of  them  into 
two,  and  consequently  makes  four  triangles  on  each  side 
of  the  median  line  of  the  neck.  These  are  named  as  fol- 
lows :  1.  Anterior  superior.  2.  Anterior  inferior.  3.  Pos- 
terior  superior.  4.  Posterior  inferior. 

Of  these  triangles,  the  anterior  superior  and  posterior 
inferior  seem,  practically,  the  most  important,  as  in  the 
former  we  tie  the  carotid  artery,  and  in  the  latter,  the 
subclavian.  It  may  be  well  here  to  notice  the  contents  of 
each  of  these  triangles. 

The  anterior  superior  triangle  is  situated  between  the 
anterior  belly  of  the  omo-hyoid,  and  the  sterno  mastoid,  the 
apex  of  the  triangle  being  formed  by  the  intersection  of 
these  muscles  opposite  the  cricoid  cartilage,  and  the  base, 
which  is  superior,  by  the  digastric  muscle.  The  carotid 
artery,  the  internal  jugular  vein,  the  par-vagum,  and  the 
sympatlietic  nerves,  are  found  in  this  triangle,  simply  cov- 
ered by  the  fascia,  the  platysma,  and  the  integuments. 

The  anterior  inferior  triangle  is  situated  below  the  ante- 
rior belly  of  the  orno-hyoid,  and  between  it  and  the  median 
line  of  the  neck,  above  the  sternal  end  of  the  clavicle ;  it 
also  contains  the  carotid  artery,  the  jugular  vein,  and  the 
accompanying  nerves,  and  is  covered  by  the  sterno-mastoid, 
sterno-hyoid,  and  sterno-thyroid  muscles.  A  portion  of 
the  thyroid  gland  is  also  seen  in  this  triangle. 

The  posterior  superior  triangle  is  between  the  trapezius 
and  sterno-mastoid,  and  above  the  posterior  belly  of  the 
omo-hyoid  muscle;  it  contains  cellular  tissue,  lymphatic 
glands,  and  the  cervical  plexus  of  nerves. 

The  posterior  inferior  triangle  is  below  the  posterior  belly 


486 


MUSCLES   OF  ANTERIOR   NECK. 


of  the  omo-hyoid,  above  the  clavicle,  and  behind  the  poste- 
rior inferior  margin  of  the  sterno-mastoid.  The  sub-davian 
artery  and  some  of  its  branches,  with  the  vein  and  brachial 
plexus  of  nerves,  are  seen  in  this  triangle. 

The  scalenus  anticus  muscle  is  situated  at  the  lower  and 
anterior  part  of  the  neck,  and  is  considered  to  be  contin- 
uous  with    the    rectus    capitis  FJG.  143. 
anticus   major.     It  arises  ten- 
dinous from  the  third,  fourth, 
fifth,  and  sixth  transverse  pro- 
cesses of  the  cervical  vertebrae, 
and   is    inserted   into  the    su- 
perior surface  of  the  first  rib  at 
its  sternal  end. 

The  scalenus  medius  is  larger 
than  the  last  and  arises  from 
the  transverse  processes  of  all 
the  cervical  vertebrae  by  tendin- 
ous fibres.  Sometimes  it  orig- 
inates only  from  the  four  or  five 
lower  cervical  vertebrae.  It  is 
inserted  into  the  superior  sur- 
face of  the  first  rib  posterior  to  the  subclavian  artery. 

The  scalenus  posticus  is  behind  the  former,  and  is  better 
seen  in  dissecting  the  muscles  of  the  spine.  It  arises  from 
the  transverse  processes  of  the  two  or  three  lower  cervical  ver- 
tebrae, and  is  inserted  into  the  superior  surface  of  the  second 
rib  between  its  tubercle  and  angle.  The  two  last  muscles  are 
by  some  regarded  as  a  single  one,  and  described  as  such. 

Function. — The  three  scaleni  bend  the  neck  forward  or  to 
one  side,  and  when  the  vertebrae  are  fixed,  elevate  the  ribs. 
The  first  scalenus  has  the  phrenic  nerve  descending  on  the 
front,  the  subclavian  vein  crossing  its  insertion,  the  sub- 

FIG.  148  represents  the  deep  Muscles  of  the  anterior  Neck,  a  Rectus  capi- 
is  anticus  major,  d  Rectus  capitis  anticus  minor,  j  Rectus  capitis  lateralis. 
6  Scalenus  anticus.  g  Scalenus  medius.  h  Scalenus  posticus.  c  f  Longus 
colli— its  lower  portion  on  the  right  side,  and  upper  portion  on  the  left  side, 
i  One  of  the  intertransversales. 


MUSCLES  OF  ANTERIOR  NECK.  48T 

daman  artery  and  brachial  plexus  behind  it,  and  the  sterno- 
mastoid  and  omo-hyoid  muscles  in  front. 

The  second  scalenus  or  medius  has  the  subclavian  and 
brachial  plexus  in  front,  and  is  covered  by  the  first. 

The  longus  colli  is  situated  close  upon  the  bodies  of  the 
vertebras,  upon  either  side  of  the  median  line.  It  arises 
from  the  bodies  of  the  three  superior  dorsal  vertebras  at 
their  sides,  and  from  the  transverse  processes  of  the  lower 
cervical  vertebras,  and  also  occasionally  by  a  slip  from  tho 
first  and  second  rib.  Its  insertion  is  into  the  front  of  the 
bodies  of  the  cervical  vertebrae. 

Function. — To  bend  the  neck  directly  forward  and  to  the 
one  side.  The  division  of  this  muscle  into  a  superior  and 
inferior  portion,  has  led  to  some  apparent  discrepancy  among 
anatomists,  as  to  its  origin  and  insertion,  though  there  is 
general  uniformity  as  to  its  several  attachments. 

Upon  this  muscle  rests  the  pharynx,  oesophagus,  and  the 
great  cervical  vessels  and  nerves  with  their  sheaths. 

Rectus  capitis  anticus  major. — At  the  superior  and  ante- 
rior part  of  the  neck  there  are  three  recti  muscles,  the 
major,  minor,  and  later  alls. 

Dissection. — These  are  deep  muscles,  and  are  seen  along 
with  the  longus  colli,  on  the  removal  of  the  oesophagus  and 
pharynx. 

The  rectus  capitis  anticus  major  arises  tendinous  from  the 
transverse  processes  of  the  four  lower  cervical  vertebrae. 
The  four  tendons  ascend,  and  becoming  fleshy,  proceed 
obliquely  inward,  forming  a  broad  and  thick  muscle,  which 
is  inserted  into  the  cuneiform  process  of  the  occipital  bone, 
just  in  front  of  the  condyle. 

Function. — To  bend  the  head  and  also  the  neck  forward. 

Eectus  capitis  anticus  minor  is  a  small  and  narrow  mus- 
cle. It  arises  from  the  front  of  the  atlas  near  its  trans- 
verse process,  and  is  inserted  into  the  cuneiform  process  of 
the  occipital  bone,  beneath  the  rectus  major. 

Function. — To  bend  the. head  forward  and  to  one  side. 
The  superior  cervical  ganglion  of  the  sympathetic  rests  in 
part  upon  this  muscle. 


488  MUSCLES  ON   POSTERIOR  NECK  AND  BACK. 

Eectus  capitis  lateralis  arises  from  the  transverse  pro- 
cess of  the  atlas,  and  is  inserted  into  the  jugular  eminence 
of  the  occipital  bone  on  the  outside  of  its  condyle.  It  is 
a  very  short  muscle,  and  its  function  is  to  bend  the  head 
to  the  one  side.  It  covers  the  vertebral  artery  and  has  the 
jugular  vein  resting  upon  it. 

SECTION   II. 

ORGANS  OF  MOTION,  OR  MUSCLES  ON  POSTERIOR  NECK  AND  BACK. 

Dissection. — Eaise  the  chest  by  placing  a  block  beneath 
it,  and  let  the  arms  and  head  hang,  so  as  to  make  the  mus- 
cles and  integument  tense.  Commence  an  incision  from 
the  external  occipital  protuberance,  which  carry  along  the 
Bpinous  processes  to  the  coccyx.  Make  a  second  from  the 
lower  cervical  spine,  to  the  acromion  process ;  and  a  third 
from  the  occipital  protuberance,  along  the  superior  trans- 
verse ridge,  towards  the  mastoid  process.  Commence  the 
dissection  at  the  second  incision,  and  raise  the  skin  upward 
and  downward,  dissecting  always  in  the  course  of  the  fibres 
of  the  muscle,  and  taking  care  to  take  oif  the  cellular  struc- 
ture, along  with  the  integument,  so  as  to  leave  the  muscles 
clean  and  distinct.  The  muscles  of  the  posterior  neck  and 
of  the  back  have  been  divided  into  six  layers. 

The  first  layer  is  superficial,  and  consists  of  two  muscles, 
the  trapezius  and  latissimus  dorsi. 

The  Trapezius,  so  called  from  its  resemblance  to  the 
mathematical  figure  of  that  name,  is  a  triangular,  broad 
muscle,  having  its  base  at  the  spine,  and  apex  at  the  acro- 
mion process  of  the  scapula.  It  is  situated  on  the  back 
part  of  the  neck  and  chest,  and  arises  from  the  external 
occipital  protuberance  and  its  superior  transverse  ridge,  by 
a  thin  aponeurotic  tendon ;  also  from  the  spinous  processes 
of  the  five  superior  cervical  vertebras,  by  the  ligamentum 
jmchre ;  and  again  tendinous  from  the  spinous  processes  of 
the  two  lower  cervical,  and  all  the  dorsal.  The  superior 
fibres  descend,  the  inferior  ascend,  and  the  middle  rim 
transversely,  all  converging  towards  the  shoulder,  to  bo 


MUSCLES  ON   POSTERIOR  NECK   AND   BACK. 


489 


inserted  into  the  outer  third  of  the  clavicle,  the  acromion 
process,  and  the  superior  edge  of  the  spine  of  the  scapula. 

Function.— -To  draw  the  shoulder  toward  the  spine.     Its 
superior  fibres  can  also  raise  the  shoulder,  while  the  in- 
ferior can   depress  it.  FIG.  149. 
The  head  can  also  he 
inclined  backward  and 
to  the  one  side  by  it. 

The  ligamentum  nu- 
chce  is  composed  of 
cellulo-1  igainentous 
matter,  broad  above, 
extending  from  the  ex- 
ternal occipital  protu- 
berance along  the  me- 
dian line,  and  attached 
to  the  spinous  pro- 
cesses of  all  the  cervi- 
cal vertebras.  It  forms 
a  complete  partition 
between  the  muscles 
upon  the  two  sides  of 
the  neck.  It  is  very 
powerful  in  the  ox, 
and  is  of  great  use  in 
supporting  the  head 
and  in  giving  attach- 
ment to  muscles. 

The  latissimus  dorsi,  as  its  name  implies,  is  truly  the 
broad  muscle  of  the  back.  It  is  situated  immediately  be- 
neath the  skin,  covering  the  whole  of  the  lower  part  of  the 
back  and  loins,  and  arises  by  a  thin  tendinous  membrane, 
from  the  six  inferior  spines  of  the  back,  and  by  the  fascia 
lumborum,  from  all  the  spines  of  the  loins  and  sacrum ;  also 

FIG.  149  represents  the  Superficial  Muscles  of  the  back  and  neck.  1  Trape- 
zius.  2  Latissimus-dorsi.  3  Infra-spinatus.  4  Teres  minor.  5  Teres  major. 
6  Obliquus  externus.  7  Serratus  magnus.  8  Pectoralis  major.  11  Sterno- 
mastoid.  12  Deltoid.  16  Gluteus  maximus. 


490  MUSCLES  ON  POSTERIOR  NECK  AND  BACK. 

from  the  posterior  third  of  the  crest  of  the  ilium,  and  by 
fleshy  slips  from  the  three  or  four  lower  ribs.  The  fibres 
from  this  extensive  origin  converge  towards  the  axilla,  so 
as  to  form  its  posterior  fold;  and  thence  go  to  be  inserted  by 
a  broad,  thick  tendon,  into  the  lower  part  of  the  posterior 
edge  of  the  bicipital  groove  of  the  humerus.  As  this  mus- 
cle ascends,  it  passes  over  the  inferior  angle  of  the  scapula, 
where  a  bursa  is  found  interposed,  and  where  also  a  fasci- 
culus of  fibres  often  connects  the  two.  At  this  point  it  is 
behind  the  teres  major,  but  as  it  proceeds  it  winds  around 
this  muscle  so  as  to  get  in  front.  The  two  tendons  are 
closely  connected,  but  separated  by  a  bursa. 

Function. — To  draw  the  arm  downward  and  backward. 
It  can  also  depress  the  shoulder  and  rotate  the  humerus  in- 
wards, and  if  the  shoulders  be  fixed  it  can  elevate  the  ribs 
and  assist  in  inspiration. 

The  second  layer  consists  of  three  muscles. 

Bliomboideus  minor. — Dissection. — Cut  through  the  trape- 
zius  along  its  spinal  attachment,  and  reflect  towards  the 
shoulder,  which  will  expose  the  rhomboidei.  This  is  a  nar- 
now  muscle,  and  seems  more  properly  to  form  a  part  of  the 
next,  the  rhomboideus  major,  with  which  it  is  so  intimately 
blended.  It  arises  by  a  thin  tendon  from  the  two  or  three 
lower  cervical  spines,  passes  obliquely  down  and  is  inserted 
into  the  base  of  the  scapula  opposite  its  spine. 

The  rhomboideus  major  arises  tendinous  from  the  four  su- 
perior dorsal  spines,  passes  down  parallel  and  in  connection 
with  the  rhomboideus  minor,  and  is  inserted  into  all  the 
base  of  the  scapula  from  its  spine  to  the  inferior  angle. 
These  two  muscles  receive  their  name  from  their  quadri- 
lateral figure. 

Function. — To  draw  the  shoulder  backward  and  upward 
toward  the  spine. 

The  levator  anguli  scapulae  is  situated  at  the  upper  and 
posterior  side  of  the  neck,  between  the  anterior  margin  of 
the  trapezius  and  the  posterior  margin  of  the  sterno-cleido- 
mastoideus.  It  arises  by  distinct  and  rounded  tendons  from 
the  transverse  processes  of  the  four  or  five  superior  cervical 


MUSCLES  OX  POSTERIOR  NECK  AND  BACK. 


491 


FIG.  150. 


vertebrae ;  these  unite  to  form  a  fleshy  belly,  which  is 
inserted  into  all  the  base  of  the  scapula  from  its  spine  to 
the  superior  angle. 

Function. — To  raise  the  shoulder,  when  acting  with  the 
trapezius. 
When  act- 
ing by  itself 
it  elevates 
the  superior 
angle  of  the 
scapula,  and 
in  propor- 
tion depress- 
es the  acro- 
mion. 

Third  lay- 
er.—  Dissec- 
tion.— Ke- 
move  the 
rhomboidei 
by  detach- 
ing them 
from  the 
base  of  the 
scapula,  and 
the  latissi- 
rnus  dor  si, 
by  dividing 

along  its  centre  and  reflecting  towards  the  spine,  and  the 
third  layer  is  exposed,  which  consists  of  the  three  follow- 
ing muscles : 

The  serratus  posticus  superior,  situated  at  the  upper  and 

FIG.  150  represents  the  Muscles  of  the  Back,  seen  after  removing  the  super- 
ficial set.  1  Trapezius.  2  Tendon  of  the  two  trapezii.  3  Spine  of  scapula. 
4  Latissimus  dorsi.  5  Deltoid.  6  Infra-spinatus,  teres-minor.  7  External 
oblique.  8  Gluteus  medius.  9  Gluteus  maximus.  10  Levator  scapulae.  11 
Rhomboideus  minor.  12  Rhomboideus  major.  13  14  Splenius  capitis  etcolli. 
15  Origin  of  latissimus  dorsi.  16  Serratus  posticus  inferior.  17  Supra  spina- 
tus.  18  Infra-spinatus.  19  Teres  minor.  20  Teres  major.  21  Long  head 
of  triceps  extensor  cubiti.  22  Serratus  major  anticus.  23  Internal  oblique. 


492  MUSCLES   ON  POSTERIOR  NECK  AND  BACK. 

back  part  of  the  chest,  arises -"by  a  thin  aponeurotic  tendon, 
from  the  ligamentum  nuchee,  the  three  inferior  spines  of 
the  neck,  and  from  the  two  or  three  superior  spines  of  the 
back,  and  is  inserted  lay  fleshy  digitations  into  the  upper 
edges  of  the  second,  third,  and  fourth  ribs. 

Function. — To  elevate  the  ribs,  and  thus,  by  expanding 
the  chest,  to  assist  in  inspiration. 

The  serratus  posticus  inferior,  situated  at  the  lower  and 
back  part  of  the  chest,,  is  a  broader  and  thinner  muscle 
than  the  last.  It  arises,  by  a  very  delicate  tendinous  ex- 
pansion, beneath  the  latissimus  dorsi,  with  which  it  is 
strongly  connected,  through  the  fascia  lumborum;  from 
the  spinous  processes  of  the  two  lower  dorsal,  and  two  or 
three  upper  lumbar  vertebra?,  and  is  inserted,  by  fleshy 
digitations,  into  the  inferior  margins  of  the  four  lower  ribs, 

Function. — To  depress  the  ribs,  and  thus  by  lessening 
the  capacity  of  the  chest,  to  assist  in  expiration.  It  is  the 
antagonist  muscle  of  the  superior  serratus. 

The  splenius  capitis  et  colli  has  its  lower  portion  con- 
cealed by  the  muscle  before  the  last ;  and  its  upper,  by  the 
trapezius.  It  arises  from  the  four  or  five  superior  spines  of 
the  back,  and  the  three  or  four  lower  of  the  neck,  and  from 
the  ligamentum  nucha?;  it  ascends  as  a  long,  flat,  and 
fleshy  muscle,  and  is  inserted,  by  two  distinct  portions — one 
for  the  head — into  the  mas toid process  of  the  temporal  bone, 
and  the  surface  between  the  two  semicircular  ridges  of  the 
occipital ;  and  the  other,  for  the  neck,  into  the  transverse 
processes  of  the  two  or  three  superior  cervical  vertebra?. 

Function. — To  bend  the  head  and  neck  backward. 

The  fourth  layer  is  seen  by  removing  the  serrati  and 
splenii,  and  consists  of  the  following  seven  muscles : 

Sacro-lumbalis ,  longissimus  dorsi,  spinalis  dorsi.  These 
three  muscles  are  associated  under  the  name  of  erector  spinw. 
The  whole  appear  as  one  mass,  occupying  the  space  between 
the  spinous  processes  and  the  angles  of  the  ribs. 

The  first  two  have  a  common  origin  from  the  posterior 
surface  of  the  sacrum,  from  the  posterior  third  of  the  crest 
of  the  ilium,  and  from  the  spinous  and  oblique  processes  of 


MUSCLES   ON  POSTERIOR   NECK   AND   BACK. 


493 


the  lumbar  vertebrae  ;  on  a  level  with  the  last  rib  a  division 
occurs.  The  sacro-lumbalis  forms  the  outermost  and  larger 
portion,  and  is  inserted  by  long  and 
slender  tendons,  into  all  the  ribs  at 
their  angles. 

The  longissimus  dorsi  is  nearest 
the  spine,  and  is  inserted  by  short 
tendons  into  the  transverse  processes 
of  all  the  dorsal  vertebra^  and  by 
tendinous  and  fleshy  slips  into  all 
the  ribs  between  their  tubercles  and 
angles. 

Function. — These  two  muscles  ex- 
tend the  spine,  and  preserve  it  in 
the  erect  state.  On  separating  these 
muscles,  six  or  eight  tendinous  and 
fleshy  slips  are  seen  coming  from 
the  superior  margin  of  the  ribs  and 
attaching  themselves  to  the  lower 
surface  of  the  sacro-lumbalis  ;  they 
are  called  the  musculi  accessorii  ad 
sacro-lumbalem. 

The  spinalis  dorsi  is  a  purely  ten- 
dinous muscle,  situated  along  the 
edges  of  the  spinous  processes.  It 
arises  tendinous  from  the  two  supe- 
rior lumbar  and  three  inferior  dorsal  spines,  and  is  inserted 
tendinous  into  the  nine  upper  dorsal  spines.  Function. — The 
same  as  the  two  last.  These  three  muscles  are  covered  by 
the  fas  da  lumborum. 

The  cervicalis  ascendens  or  descendens,  appears  to  be  a 
continuation  of  the  sacro-lumbalis.  It  arises  from  the  upper 

FIG.  151  represents  the  deep  Muscles  of  the  back  and  neck.  1  3  Longissi- 
mus dorsi,  its  lower  and  upper  portions.  2  Upper  part  of  sacro-lumbalis.  4 
Spinalis  dorsi.  5  Cervicalis  descendens.  6  Transversalis  cervicis.  7  Trachelo 
mastoideus.  8  Complexus.  9  Transversalis  cervicis,  its  insertion.  10  Semi- 
spinalis  dorsi.  11  Semi-spinalis  colli.  12  Rectus  capitis-posticus-minor.  13 
Rectus  capitis-posticus  major.  14  Obliquus  capitis  superior.  15  Obliquus  ca- 
pitis  inferior.  16  Multifides  spina3.  17  17  Levatores  costarum.  18  Inter- 
transversales.  19  Quadratus  lumborum. 


494  MUSCLES   ON   POSTERIOR   NECK   AND   BACK. 

edges  of  the  four  or  five  superior  ribs,  by  as  many  tendons, 
and  forms  a  small  fleshy  belly,  which  is  inserted  by  three 
or  four  tendons  into  the  transverse  processes  of  the  fourth, 
fifth,  and  sixth  cervical  vertebras.  Function. — To  draw  the 
neck  backward  and  to  one  side. 

Transversalis  colli  (or  cervicis)  appears  to  be  a  continua- 
tion of  the  longissimus  dorsi,  and  is  about  the  same  size 
with  the  last.  It  arises  from  the  transverse  processes  of 
the  four  or  six  superior  dorsal,  and  is  inserted  by  small  ten- 
dons into  the  transverse  processes  of  the  four  or  five  lower 
cervical  vertebrae.  Function. — To  draw  the  neck  backward. 

The  tracJielo-mastoideus ,  situated  between  the  last  and  the 
complexus,  seems  also  to  be  a  continuation  of  the  longissi- 
mus dorsi,  upward.  It  arises  tendinous  from  the  transverse 
processes  of  the  three  or  four  superior  dorsal,  and  four  or 
five  inferior  cervical,  and  forms  a  very  delicate  and  slender 
muscle,  which  ascends  to  be  inserted  into  the  posterior  part 
of  the  mastoid  process,  beneath  the  splenius.  Function. — To 
bend  the  head  and  neck  backward  and  to  rotate  to  one  side. 

The  complexus  is  seen  between  the  upper  heads  of  the 
diverging  splenii,  and  is  a  large  and  thick  muscle.  The 
tendinous  matter  noticed  in  its  substance,  gives  it  the  com- 
plex appearance,  whence  its  name  is  derived.  It  arises 
from  the  transverse  and  oblique  processes  of  the  five  or 
seven  superior  dorsal,  and  three  or  four  inferior  cervical, 
and  is  inserted  into  the  occipital  bone,  along  with  its  fel- 
low, on  either  side  of  the  median  line,  between  the  two 
semicircular  ridges.  Function. — To  draw  the  head  back. 

Fifth  layer,  (Fig.  151.) — Dissection. — Kemove  the  muscles 
of  the  fourth  layer,  by  dividing  them  in  their  middle  and 
reflecting  them  to  either  end.  This  layer  consists  of  the 
following  five  muscles : 

The  rectus  capitis  rjosticus  major,  is  of  a  triangular  shape, 
arises,  tendinous  and  fleshy,  from  the  spinous  process  of 
the  vertebra  dentata,  and  is  inserted  broad  into  the  inferior 
transverse  ridge  of  the  os-occipitis.  Function. — To  draw 
the  head  back  and  rotate  it  on  the  atlas. 

The  rectus  capitis  posticus  minor,  like  the  last,  is  also 


MUSCLES  ON  POSTERIOR  NECK  AND   BACK.  495 

triangular,  having  its  apex  below  and  "base  above,  being 
situated  to  the  inner  side  of  the  rectus  major,  and  with  it 
occupying  the  space  between  the  head  and  the  first  and 
second  vertebrae.  It  arises  from  the  tubercle  on  the  poste- 
rior part  of  the  atlas,  and  passes  upward  and  outward  to 
be  inserted  broad  into  the  rough  surface  between  the  infe- 
rior transverse  ridge,  and  foramen  magnum  of  the  occipital 
bone.  Function. — To  draw  the  head  backward. 

The  obliquus  capitis  superior  arises  narrow  from  the 
transverse  process  of  the  atlas,  and  is  inserted,  by  a  broad 
attachment  to  the  occipital  bone,  behind  its  mastoid  pro- 
cess, function. — To  bend  the  head  to  one  side  and  draw 
it  backward. 

The  obliquus  capitis  inferior  arises  from  the  spinous  pro- 
cess of  the  vertebra  dentata,  passes  upward  and  outward, 
and  is  inserted  into  the  extremity  of  the  transverse  process 
of  the.  atlas.  Function. — To  rotate  the  atlas  and  head  upon 
the  dentata  or  second  vertebra. 

These  four  little  muscles  form  nearly  an  equi-lateral 
triangle.  The  base  Consists  of  the  recti  along  the  middle 
line.  The  apex  is  the  extremity  of  the  transverse  process, 
and  the  sides  of  the  triangle  are  the  superior  and  inferior 
oblique  muscles.  A  quantity  of  fatty  and  cellular  struc- 
ture fills  up  this  triangle,  and  deep  in  it  are  seen  the  verte- 
bral artery,  a  plexus  of  veins,  and  the  sub-occipital  nerve. 

The  semi-spinalis  colli  et  dorsi  appears  as  one  continued 
muscle,  though  it  has  been  distinguished  into  two.  They 
extend  from  transverse  to  spinous  processes,  encircling  about 
one-half  the  vertebral  column — hence  their  name.  They 
are  with  difficulty  distinguished  from  the  multifidus  spinae. 

The  semi-spinales  colli  arise  from  the  transverse  processes 
of  the  five  superior  dorsal  vertebrae,  and  are  inserted  into 
the  spinous  processes  of  the  middle  cervical  vertebrae. 

The  semi-spinales  dorsi  arise  from  the  transverse  pro- 
cesses of  the  six  lower  dorsal  vertebrae,  and  are  inserted 
into  the  spinous  processes  of  the  two  lower  cervical,  and 
four  upper  dorsal.  Function. — To  draw  the  spine  obliquely 
backward. 


496  MUSCLES  ON  POSTERIOR  KECK  AND  BACK. 

Sixth  layer,  (Fig  151.) — Dissection.— Eemove  tlie  semi- 
spinales.  This  layer  consists  of  the  deeper  and  more  deli- 
cate muscles  of  the  back  and  ribs. 

The  inter-spinales ,  as  their  name  implies,  are  situated 
"between  the  spinous  processes  of  contiguous  vertebras. 
They  consist  of  a  succession  of  small,  short  muscles,  which, 
in  the  neck,  are  in  pairs,  owing  to  the  bifid  state  of  the 
cervical  spines.  In  the  back  they  are  quite  indistinct,  and 
in  the  loins  they  are  mostly  ligamentous,  having  a  few 
muscular  fibres  intermixed.  Function. — To  extend  the 
spine  and  keep  it  erect. 

The  intertransversales  are  also  short  muscles,  and  as 
their  name  indicates,  are  situated  between  the  transverse 
processes.  They  are  double  and  distinct  in  the  neck,  very 
indistinct  in  the  back,  and  feeble  in  the  loins. 

Function. — To  bend  the  spine  laterally. 

The  multifidus  spince  consist  of  a  multitude  of  small, 
fleshy  and  tendinous  fasciculi,  which  are  parallel  to  each 
other,  and  extend  from  transverse  to  spinous  processes,  the 
whole  length  of  the  spine.  They  arise  each  from  the  trans- 
verse or  oblique  piocess  of  one  vertebra,  and  are  inserted 
into  the  spinous  process  of  the  vertebra  above,  the  fasci- 
culi sometimes  extending  to  the  second  or  third  vertebra 
above. 

At  the  lower  part  of  the  spine  the  multifidus  spinaa 
have  also  an  attachment,  tendinous  and  fleshy,  to  the  back 
part  of  the  sacrum,  and  the  posterior  part  of  the  ilium. 
Function. — To  support  the  spine  and  bend  it  to  one  side. 

The  levatores  costarum  are  twelve  in  number,  on  each 
side  of  the  chest,  and  are  parallel  to  the  external  intercos- 
tal muscles.  Each  arises  from  the  transverse  processes  of 
the  dorsal  and  the  last  cervical  vertebra,  and  is  inserted  into 
the  ribs  below,  between  the  tubercle  and  angle.  Func- 
tion.— To  elevate  the  ribs  and  assist  in  inspiration. 

The  supra-spinales  are  little  fleshy  fasciculi,,  or  bands, 
described  as  being  situated  exclusively  upon  the  spinous 
processes  of  the  cervical  vertebrae 

It  will  be  seen  from  the  above  description  of  the  muscles 


(ESOPHAGUS.  49  T 

of  the  back,  that  no  very  great  regularity  belongs  to  their 
several  attachments,  a  fact  which  explains  the  apparent 
discrepancy  among  different  authors. 

SECTION   III. 
ORGANS  OF  DEGLUTITION — CESOPHAGUS. 

The  oesophagus,  (own/,  to  bear,  $ay°?>  food,)  or  food  duct, 
is  a  continuation  of  the  pharynx,  and,  as  its  name  implies, 
is  designed  to  convey  our  food  and  drinks  from  the  mouth 
and  pharynx  downward  into  the  stomach. 

It  commences  at  the  lower  portion  of  the  pharynx,  op- 
posite the  fifth  cervical  vertebra,  and  behind  the  cricoid 
cartilage,  at  its  lower  border.  It  then  descends  the  neck 
nearly  on  the  median  line,  lying  first  a  little  to  the  left 
of  this  line  in  the  neck,  then  inclining,  as  it  enters  the 
chest,  to  the  right;  then  again  to  the  left,  before  it  enters 
the  stomach.  This  flexuosity  explains  the  occasional  dif- 
ficulty of  introducing  the  probang.  It  passes  behind  the 
trachea,  the  arch  of  the  aorta,  the  pericardium,  along  the 
posterior  mediastinum,  and  in  front  of  the  thoracic  aorta, 
to  the  diaphragm,  and  terminates  at  the  cardiac  orifice  of 
the  stomach,  opposite  the  tenth  dorsal  vertebra.  It  is 
made  up  of  three  distinct  coats,  with  the  blood-vessels  and 
nerves.  The  coats  are  the  external,  the  middle,  and  the 
internal,  or  muscular,  cellular,  and  mucous. 

The  muscular  coat  is  composed  of  two  very  distinct  planes 
of  fibres — the  external,  running  longitudinally,  and  the 
internal,  circularly,  both  being  prolonged  upon  the  stomach. 
The  cellular  coat  forms  the  connecting  medium  between  the 
muscular  and  mucous  coats,  and  conducts  the  blood-vessels 
and  nerves  to  the  latter.  The  mucous  coat  is  pale,  thin, 
disposed  in  longitudinal  folds,  and  covered  by  a  delicate 
epithelium  or  cuticle.  It  also  contains  mucous  follicles, 
sometimes  called  cesophageal  glands,  whose  orifices  are 
seen  in  the  depressions  between  the  longitudinal  folds. 

The  arteries  of  the  oasophagus  come  from  the  inferior 
thyroid  in  the  neck ;  from  the  bronchial  and  aorta  in  the 
chest ;  and  from  the  diaphragmatic  and  coronary  artery  of 
32 


498 


PNEUMOGASTRIC  NERVE. 


FIG.  152. 


the  stomach.  Its  veins  enter  the 
inferior  thyroid,  the  bronchial,  vena 
azygos,  superior  vena  cava,  internal 
mammary,  and  coronary  vein  of  the 
stomach.  It  has  also  lymphatics  dis- 
charging their  contents  into  the 
ganglia  which  surround  it. 

The  nerves  of  the  oesophagus  are 
numerous  and  consist  chiefly  of 
branches  from  the  pneumo-gastric, 
which  surround  it  and  constitute  the 
cesophageal  plexus. 

The  pneumo-gastric,  (Fig.  152,)  or 
par  vagum,  being  so  largely  con- 
nected with  the  oesophagus,  as  well 
as  with  a  variety  of  other  important 
organs,  demands  a  description  in 
this  place.  This  nerve,  (classed 
along  with  the  eighth  pair,  though 
a  more  strict  classification  makes  it 
the  tenth,)  arises  by  numerous  fila- 
ments, generally  ten  or  twelve,  from 
the  medulla  oblongata  in  the  fissure 
between  the  corpora  olivare  and  res- 
tiforme.  These  unite  into  one  nerve, 
which  joins  the  glosso-pharyngeal 
above,  and  the  spinal  accessory  be- 
low, and  the  whole  proceed  to  the 
foramen  lacerum  posterius,  through 


FIG.  152  represents  the  eighth  pair  of  nerves.  1  Corpus  pyramidale.  2  Pons 
Varolii.  3  Corpus  olivare.  4  Corpus  restiforme.  5  Facial  nerve.  6  Origin 
of  glosso-pharyngeal.  7  Ganglionum  petrosum.  8  Trunk  of  glosso-pharyn- 
geal. 9  Spinal  accessory.  10  Ganglion  of  par-vagum  or  pneumogastric  nerve. 
11  Its  ganglion  taking  the  plexiform  arrangement.  12  Trunk  of  par  vagum. 
13  Its  pharyngeal  branch.  14  Pharyngeal  plexus.  15  Superior  laryngeal 
nerve.  16  Cardiac  branches.  17  Recurrent  branch.  18  Anterior  pulmonary 
branches.  19  Posterior  pulmonary  branches.  20  (Esophageal  plexus.  2J 
Gastric  branches.  22  Point  where  spinal  accessory  arises.  23  Sterno-mastoid 
branches.  24  Branches  to  the  trapezius. 


PNEUMOGASTRIC  NERVE.  499 

which  they  pass,  and  go  to  their  several  destinations.  In 
the  foramen  lacerum,  the  par  vagum  is  separated  from  the 
other  nerves  by  dense  cellular  membrane,  and  from  the 
jugular  vein,  which  is  behind,  by  a  spicula  of  bone.  At 
this  point  it  also  presents  a  swelling  called  the  superior 
ganglion,  and  below  this  another  enlargement  called  the 
inferior  gangli6n,  about  an  inch  in  length.  From  these, 
filaments  communicate  with  the  facial,  spinal  accessory, 
glosso-pharyngeal,  sympathetic,  and  superior  spinal  nerves, 
constituting  a  plexus  termed  the  basilar  plexus.  From  the 
inferior  ganglion,  which  is  of  reddish  color,  the  par  vagum 
descends  the  forepart  of  the  neck,  along  with  the  carotid 
artery  and  jugular  vein,  behind  and  between  those  vessels, 
and  enclosed  in  the  same  sheath  with  them.  At  the  root 
of  the  neck,  the  right  par  vagum  enters  the  chest  between 
the  subclavian  vein  and  artery,  crossing  the  latter  at  right 
angles  ;  on  the  left,  this  nerve  runs  parallel  to  the  sub- 
clavian artery,  crossing  the  arch  of  the  aorta.  Both  nerves 
now  proceed  through  the  thorax  to  the  posterior  part  of  the 
root  of  the  lungs,  in  the  posterior  mediastinum,  and  descend 
along  the  oesophagus,  through  the  diaphtagni,  to  terminate 
upon  the  stomach. 

The  par  vagum  in  its  course  gives  off  the  following 
branches  : 

The  auricular  commences  at  the  superior  ganglion,  con- 
nects with  the  glosso-pharyngeal,  enters  a  small  canal  of 
the  petrous  bone,  upon  the  inside  of  the  styloid  process, 
then  proceeds  to  join  the  facial  in  the  aqueduct  of  Fallo- 
pius,  and  finally  escapes  in  front  of  the  mastoid  process  to 
supply  the  ear  and  its  integuments. 

The  pliaryngeal  comes  from  the  inferior  ganglion  at  the 
base  of  the  cranium,  receives  a  branch  from  the  spinal  acces- 
sory, and  descends  behind  the  carotid  artery  to  the  side  of 
the  pharynx,  at  the  upper  margin  of  its  middle  constrictor. 
Here  it  anastomoses  with  branches  from  the  glosso-pharyn- 
geal, the  superior  laryngeal,  and  the  sympathetic,  forming 
the  pharyngeal  plexus ,  which  supplies  the  mucous  and  mus- 
cular structures  of  the  pharynx. 


500  PNEUMOGASTRIC  NERVE. 

The  superior  laryngeal  also  arises  from  the  inferior  gang- 
lion, and  taking  an  arched  course  downward  behind  the 
internal  carotid  artery,  enters  the  thyro-hyoid  membrane 
along  with  the  superior  laryngeal  artery,  and  principally 
supplies  the  mucous  membrane  of  the  larynx.  This  nerve 
is  regarded  as  one  of  sensation. 

The  cardiac  nerves  have  their  origin  from  the  vagus  at 
the  root  of  the  neck,  by  two  or  three  branches,  which  cross  the 
carotid  artery  and  join  the  sympathetic  in  the  cardiac  plexus. 

The  inferior  laryngeal  (or  recurrent  nerve)  comes  from 
the  par  vagurn  upon  the  right  side,  as  it  crosses  the  sub- 
clavian  artery.  It  curves  around  and  behind  this  artery, 
and  ascends  to  the  larynx  along  the  side  of  the  trachea, 
covered  by  the  inferior  thyroid  and  common  carotid  arte- 
ries ;  at  its  origin  it  gives  off  filaments  to  the  cardiac  plexus, 
trachea,  oesophagus,  and  thyroid  gland,  and  finally  termin- 
ates by  supplying  all  the  muscles  of  the  larynx  except  the 
crico-thyroid.  Branches  have  also  been  traced  into  the 
mucous  membrane  of  the  larynx. 

The  recurrent  of  the  left  side  differs  from  that  of  the 
right,  in  curving  round  the  arch  of  the  aorta  and  ductus 
arteriosus.  The  recurrent,  or  inferior  laryngeal  nerves  are 
essentially  motor. 

Pulmonary  brandies. — These  come  from  the  vagus,  near 
the  root  of  the  lungs,  and  form  a  plexus,  in  front  and  be- 
hind the  root,  called  the  anterior  and  posterior  pulmonary 
plexuses.  The  posterior  is  the  larger,  and  both  anastomose 
with  the  sympathetic  and  phrenic  nerves,  and  accompany 
the  pulmonary  vessels  and  bronchial  tubes,  to  supply  the 
lungs. 

(Esopliageal  branches. — These  come  from  the  pneumogas- 
tric  above  and  below  the  root  of  the  lung;  but  it  is  below 
the  root  that  the  nerves,  on  either  side,  come  together, 
and,,  surrounding  the  oesophagus,  constitute  the  cesophageal 
plexus.  The  left  vagus  goes  in  front,  while  the  right  passes 
behind  the  cesophagus. 

Gastric  branches. — These  are  the  terminating  branches  of 
the  pneumogastric  upon  the  stomach.  They  form,  around 


BLOOD-VESSELS  OF  THE  NECK.  501 

the  cardiac  orifice  of  the  stomach,  the  cardiac  plexus.  The 
right  vagus  goes  to  the  posterior  surface  of  the  stomach, 
communicating  with  the  solar,  renal,  splenic,  and  hepatic 
plexuses;  while  the  left  is  distributed  on  the  anterior 
surface,  and  lesser  curvature  of  the  stomach,  sending  some 
branches,  by  the  lesser  omentum,  to  the  liver  and  gall- 
bladder. 

It  is  evident,  then,  that  the  pneumogastric  is  a  com- 
pound nerve,  that  is,  that  it  combines  filaments  of  sensa- 
tion and  motion — that  it  connects  together  a  great  variety 
of  organs,  as  the  pharynx,  oesophagus,  larynx,  trachea, 
lungs,  heart,  and  stomach,  and  influences  an  equally  great 
variety  of  functions,  as  deglutition,  voice,  respiration,  cir- 
culation, and  digestion. 

The  oesophagus,  besides  the  pneumogastric  nerves,  i« 
also  supplied  with  branches  from  the  thoracic  ganglia  of 
the  sympathetic. 

SECTION   IV. 

ORGANS   OF  CIRCULATION  OF  THE  NECK. 

The  organs  of  circulation  in  the  neck  comprise  its  blood- 
vessels, and  consist  of  the  arteries  and  veins. 

The  arteries  supplying  the  upper  part  of  the  neck  are, 
the  superior  thyroid,  facial,  and  occipital — branches  of  the 
external  carotid.  The  vertebral,  the  thyroid  axis,  and  the 
cervicalis  posterior,  supply  the  lower  part  of  the  neck,  and 
come  from  the  subdavian. 

The  external  carotid  has  been  stated  elsewhere,  to  arise 
from  the  common  carotid,  and  this  latter  to  arise  from  the 
arteria  innominata,  upon  the  right  side,  opposite  the  sterno- 
clavicular  articulation,  and  upon  the  left,  from  the  arch  of 
the  aorta.  Both  common  carotids  now  ascend  the  neck 
nearly  in  a  vertical  direction,,  having  in  front,  at  their  ori- 
gin, the  sterno-thyroid,  the  sterno-hyoid,  and  sterno-mastoid 
muscles ;  the  descendens  noni  nerve  along  the  middle  front, 
and  outside  the  sheath  of  the  vessels,  while  the  omo-hyoid- 
eus  crosses  in  front  about  their  middle.  On  the  inside  are 


502 


BLOOD-VESSELS  OF  THE  NECK. 


seen  the  larynx,  the  trachea,  oesophagus,  and  thyroid 
gland;  on  the  outside,  the  internal  jugular  vein  in  the 
same  sheath  with  the  artery;  "behind,  these  vessels  rest 
upon  the  transverse  processes  of  the  cervical  vertebra,  the 
longus  colli,  and  rectus  capitis  anticus  major  muscles,  the 

FIG.  153. 


37- 


4S 


inferior  thyroid  arteries,  and  the  inferior  laryngeal  and 
sympathetic  nerves.  The  common  carotids  are  also  cov- 
ered in  front  hy  the  common  integuments,  platysma  my- 
oides,  and  superficial  fascia  of  the  neck. 

FIG.  153  represents  the  Anterior  Neck,  showing  its  Blood-vessel,  &c.  &c. 
1  Anterior  bellies  of  the  digastric  muscle.  2  3  Mylo-hyoideus.  4  Hyo-glos- 
sus.  5  Stylo-glossus.  6  Styloid  process.  7  Bifurcation  of  external  carotid 
into  internal  maxillary  and  temporal.  8  Posterior  auricular  branch  of  the 
facial  nerve  and  artery.  9  Stylo-pharyngeus,  and  middle  constrictor  of  the 
pharynx.  11  Mastoid  branch  of  external  carotid.  12  Superior  thyroid  ar- 
tery. 13  Thyro-hyoid  membrane.  14  Thyro  hyoid  muscle.  15  15  Sterno- 
Ihyroid.  16  Thyroid  gland.  17  17  Omo-hyoid  muscle.  18  18  Sterno  hyoid. 
19  Sterno-mastoid.  20  Upper  attachment  of  the  sterno-mastoid.  22  Obliquus 
capitis-superior.  23  Complexus  muscle.  24  Splenius  capitis.  25  Levator 
anguli  scapulaj.  26  Scalenus  posticus.  a  Scalenus  medius.  b  Scalenus  an- 


BLOOD-VESSELS  OF  THE  NECK.  503 

Each  common  carotid  terminates  opposite  the  upper  bor- 
der of  the  thyroid  cartilage,  by  dividing  into  the  external 
and  internal  carotids. 

From  this  point,  the  external  carotid  ascends  to  the  neck 
of  the  lower  jaw,  where  it  ends  in  the  temporal  and  inter- 
nal maxillary  arteries.  In  this  course  it  is  crossed,  near  its 
origin,  by  the  lingual  nerve,  then  by  the  stylo-hyoid  and 
digastric  muscles ;  and,  still  higher,  it  is  imbedded  in  the 
parotid  gland,  and  crossed  by  the  facial  nerve.  The  pla- 
tysma,  superficial  fascia,  and  skin  form  the  superficial 
covering  in  front,  while  behind,  it  is  separated  from  the 
internal  carotid,  by  the  stylo-glossus  and  stylo-pharyngeus 
muscles,  and  the  glosso-pharyngeal  nerve. 

The  external  carotid  gives  off  ten  branches,  which  have 
been  already  detailed  in  describing  those  of  the  head.  We 
shall,  therefore,  only  recapitulate  here  those  belonging  to 
the  neck. 

The  superior  thyroid,  arising  from  the  anterior  part  of 
the  external  carotid,  near  its  origin,  descends  beneath  the 
omo-hyoid  and  sterno-thyroid  muscles,  to  the  thyroid 
gland.  In  its  course  it  gives  off  the  following  branches : 

Superficial  branches  to  the  integuments  and  superficial 
muscles  ;  hyoid,  to  the  lower  border  of  the  hyoid  bone  and 
its  muscles ;  superior  laryngeal,  which  goes  along  with  the 
superior  laryngeal  nerve,  through  the  thyro-hyoid  mem- 
brane, and  is  distributed  to  the  mucous  membrane  and 
muscles  of  the  larynx ;  inferior  laryngeal,  supplying  the 

ticus.  c  Common  carotid  artery,  d  d  Subclavian.  e  Brachial  plexus.  /  g 
Internal  jugular  vein,  h  Inferior  constrictor,  i  (Esophagus,  j  Trapezius. 
k  Deltoid.  /  Pectoralis  major — its  clavicular  portion,  m  Its  sternal  portion. 
n  Subclavius  muscle,  o  Axillary  artery.  27  Facial  artery.  28  Its  submen- 
tal  branch.  29  Hypoglossal  nerve.  30  Lingual  artery.  31  External  carotid. 
32  Posterior  auricular  artery.  33  Facial  nerve.  34  Glosso-pharyngeal  nerve. 
35  Occipital  artery.  36  Superior  laryngeal  nerve.  37  Descendens  noni 
nerve.  38  Spinal  accessory  nerve.  39  Princeps  cervicis  artery.  40  supra- 
scapular  artery.  41  Transversalis  colli.  42  Thyroid  axis.  43  Inferior  thyroid 
artery.  44  Vertebral  artery.  45  Par  vagum  nerve.  46  Internal  mammary 
artery.  47  Phrenic  nerve.  48  Communicating  nerve.  49  Second,  third,  and 
fourth  cervical  nerves.  50  Cervical  plexus.  51  Cervicalis  ascendens  artery. 
52  Brachial  plexus. 


504 


BLOOD-VESSELS  OF  THE  NECK. 


crico-thyroid  membrane,  and  entering  into  the  interior 
of  the  thyroid  gland,  and  anastomosing  freely  with  the 
inferior  thyroid. 

The  facial  artery,  called  also  the  labial,  or  external  max- 
illary, arises  also  from  the  front  of  the  external  carotid, 
opposite  the  os-hyoides,  and  ascends  to  the  lower  jaw 
behind,  and  in  the  substance  of  the  submaxillary  gland. 
Thence  it  proceeds  to  the  angle  of  the  mouth,  and  thence 
by  the  side  of  the  nose,  to  the  angle  of  the  eye,  where  it 
terminates  by  anastomosing  with  the  ophthalmic.  Its 
branches  supplying  any  portion  of  the  neck,  are  chiefly  the 
glandular,  distributed  to  the  submaxillary  and  lymphatic 
glands,  and  the  submental,  which  leaves  the  facial  just  as 
it  is  mounting  over  the  lower  jaw,  and  proceeds  forward, 
covered  by  this  bone,  passing  over  the  anterior  belly  of  the 
digastricus,  and  beneath  the  origin  of  the  mylo-hyoideus 
to  the  chin,  which,  with  the  adjacent  muscles,  it  supplies, 
and  ends  by  anastomosing  with  the  inferior  dental  and 
eublingual  branches. 

The  occipital  arises  opposite  the  facial,  from  the  posterior 
part  of  the  external  carotid,  and  ascends  backward  behind 
the  posterior  belly  of  the  digastric,  the  sterno-mastoid,  and 
trachelo-mastoid  muscles,  to  the  groove  at  the  root  of  the 
mastoid  portion  of  the  temporal  bone.  It  now  proceeds 
horizontally  backward,  between  the  splenius  and  complexus 
muscles,  to  the  mesial  line  of  the  atlas,  and  thence  ascends 
upon  the  occiput,  terminating  in  numerous  branches  which 
anastomose  with  its  fellow,  the  posterior  auricular,  and 
the  temporal  arteries.  Its  cervical  branches  supply  the 
superficial  and  deep  muscles  on  the  posterior  and  superior 
part  of  the  neck.  The  arteria  princeps  cervicis  is  the  name 
applied  to  the  deep  branch  which  descends  to  the  com- 
plexus and  semi-spinalis  muscles,  and  anastomoses  with 
the  profunda  cervicis  of  the  subclavian,  thus  forming  the 
collateral  circulation  between  the  branches  of  the  external 
carotid  and  subclavian  arteries. 

The  subclavian  artery,  (Figs.  120, 1535)  on  the  right  side, 
arises  from  the  arteria  innominata,  opposite  the  sterno-cla- 


BLOOD-VESSELS  OF  THE  NECK.  505 

vicular  articulation ;  thence  it  proceeds  obliquely  outward 
to  the  inner  margin  of  the  scalenus  anticus  muscle,  con- 
stituting its  first  stage.  It  now  passes  between  the  scale- 
nus anticus  and  scalenus  medius,  forming  its  second  stage. 
After  emerging  from  these  muscles  it  proceeds  downward 
and  outward,  beneath  the  clavicle,  to  the  lower  margin  of 
the  first  rib,  forming  its  third  stage,  where  it  terminates 
as  subclavian,  and  becomes  axillary. 

The  right  subclavian  has  anterior  to  it,  in  its  first  stage, 
the  internal  jugular  and  subclavian  veins,  the  pneumo- 
gastric,  phrenic,  and  cardiac  nerves ;  the  sterno-mastoid, 
sterno-hyoid  and  sterno-thyroid  muscles.  Behind  are  the 
inferior  laryngeal  and  sympathetic  nerves,  the  vertebral 
vein,  and  some  cellular  tissue  and  lymphatic  glands.  In  its 
second  stage  it  lies  between  the  scaleni  muscles,  separated 
by  the  scalenus  anticus  from  the  subclavian  vein  and  phrenic 
nerve,  and  accompanied  by  the  brachial  plexus  of  nerves. 
In  the  third  stage  the  subclavian  vein,  the  subclavian  mus- 
cle, and  the  clavicle  are  in  front ;  the  brachial  plexus  and 
the  omo-hyoid  are  above  and  external,  and  behind  are  the 
scalenus  posticus  and  the  first  rib,  while  the  skin,  platysma, 
and  fascia  form  the  superficial  covering. 

The  left  subclavian  differs  from  the  right  in  having  its 
origin  from  the  arch  of  the  aorta ;  in  being  longer ;  in  pur- 
suing nearly  a  vertical  course  to  the  scaleni  muscles ;  in 
having  the  pneumogastric  running  parallel  with  instead  of 
crossing  it ;  in  not  having  the  recurrent  passing  around  it ', 
in  having  the  vena  innominata,  left  carotid,  left  lung,  and 
pleura  in  front ;  and  in  having  the  thoracic  duct  and  lon- 
gus  colli  muscle  behind.  In  the  second  and  third  stages 
the  relations  of  the  subclavian  are  nearly  the  same  on  both 
sides. 

BRANCHES   OF  THE  SUBCLAVIAN  SUPPLYING  THE  NECK. 

The  vertebral  artery  is  the  largest  branch,  and  comes  off 
from  the  subclavian  at  its  upper  and  posterior  part.  It  then 
ascends  upon  the  vertebral  column  behind  the  inferior  thy- 
roid artery,  and  after  a  short  course  enters  the  foramen  in 


506  BLOOD-VESSELS  OF  THE  NECK. 

the  transverse  process  of  the  fifth  or  sixth,  and  sometimes 
o^  the  seventh  cervical  vertehra.  It  passes  upward  in  the 
"bony  canal  formed  by  the  several  foramina  placed  one  above 
another  in  the  corresponding  transverse  processes,  as  high 
as  the  dentata  or  second  vertebra.  Here  it  bends  outward 
and  backward  to  the  foramen  in  the  transverse  process  of 
the  atlas,  and  then  makes  a  very  remarkable  curve  inward 
and  backward,  round  the  articulation  of  the  atlas,  entering 
the  foramen  magnum  through  the  dura  mater.  It  ascends 
upon  the  medulla  oblongata,  and  at  the  lower  margin  of 
the  pons,  it  unites  with  its  fellow  to  form  the  basilar 
artery. 

In  the  canal  the  vertebral  artery  sends  out  anterior,  pos* 
terior,  and  external  branches,  supplying  the  intertransver- 
sales,  complexus,  splenius,  rectus  capitis  anticus  major,  and 
scaleni  muscles ;  while  its  internal  branches  go  into  the 
spinal  canal  and  supply  the  dura  mater,  and  spinal  marrow. 
In  its  transverse  bend,  between  the  atlas  and  occiput,  it 
distributes  a  number  of  branches  to  the  posterior  recti  and 
oblique  muscles  of  the  head.  It  supplies  also  the  spinal 
nerves,  and  at  the  foramen  magnum  gives  off  the  anterior 
and  posterior  spinal  arteries  that  descend  the  cord  its  whole 
length.  The  remaining  branches  of  the  vertebral  and 
basilar  arteries,  are  given  in  the  account  of  the  brain. 

The  thyroid  axis  arises  from  the  subclavian  at  its  upper 
part  and  near  the  inner  edge  of  the  scalenus  anticus.  It  is 
a  short,  thick  trunk,  and  gives  off  four  principal  branches  : 

The  inferior  thyroidj  the  superior  scapular  or  transver- 
salis  humerij  the  posterior  scapular  or  transversalis  collij 
and  the  cervicalis  anterior  or  ascending  cervical. 

The  inferior  thyroid  ascends  behind  the  common  carotid 
to  the  thyroid  gland,  where  it  anastomoses  with  the  supe- 
rior thyroid,  supplying  in  its  course  the  trachea,  oesopha- 
gus, and  lower  part  of  the  larynx. 

The  superior  scapular  proceeds  behind  the  clavicle  ob- 
liquely outward  to  the  supra  scapular-notch,  over  whose 
ligament  it  passes  to  supply  the  supra-spinatus,  and  then 
goes  beneath  the  acromion  to  the  infra-spinatus  and  teres 


BLOOD-VESSELS  OF  THE  NECK.  507 

minor.  In  its  course  it  crosses  the  scalenus  anticus,  the 
phrenic  nerve,  and  the  brachial  plexus.  This  vessel  not 
unfrequently  comes  from  the  subclavian. 

The  transversalis  colli,  or  posterior  scapular  passes  trans- 
versely outward  over  the  scaleni  muscles,  and  through  the 
brachial  plexus  to  the  superior  posterior  angle  of  the  sca- 
pula, where  it  ends*  in  two  branches,  the  superficial  cervical, 
supplying  the  trapezius,  splenius,  and  levator  scapulae ;  and 
the  continued  trunk,  the  posterior  scapular,  which  descends 
along  the  base  of  the  scapula  to  supply  the  rhomboid  and 
other  muscles  arising  from  this  quarter.  It  anastomoses 
with  the  subscapular,  a  branch  of  the  axillary. 

The  cervicalis  anterior  or  ascending  cervical  ascends  upon 
the  scalenus  anticus,  supplying  it,  the  longus  colli  and  the 
tectus  capitis  anticus  major,  and  sending  branches  to  th$ 
spinal  cord  and  its  membranes. 

The  pro/undo,  cervicis,  or  cervicalis  posterior,  arises  from 
the  upper  and  back  part  of  the  subclavian,  on  a  level  with 
and  outside  of  the  vertebral ;  it  ascends  outward  and  back- 
ward between  the  transverse  processes  of  the  sixth  and 
seventh  cervical  vertebrae,  ascending  on  the  back  of  the  neck 
to  supply  the  complexus  and  other  deep  muscles,  and  anas- 
tomosing with  the  descending  branches  of  the  occipital. 
This  vessel  is  sometimes  a  branch  of  the  superior  intercostal. 

VEINS   OF   THE   NECK,    (Fig.    154.) 

The  veins  of  the  neck  belong  to  the  external  jugular, 
internal  jugular,  anterior  jugular,  and  subclavian  veins. 

The  external  jugular  begins  at  the  angle  of  the  lower  jaw 
by  the  junction  of  the  internal  maxillary  and  temporal 
veins  ;  it  then  descends  the  neck,  crossing  the  sterno-mas- 
toideus,  covered  by  the  platysma  myoides  and  superficial 
cervical  fascia.  At  the  root  of  the  neck  it  penetrates  the 
deep  cervical  fascia  behind  the  attachment  of  the  sterno- 
mastoideus,  and  terminates  in  the  subclavian  on  the  out- 
side of  the  internal  jugular.  Its  upper  portion  is  accom- 
panied by  the  auricularis  magnus  nerve,  one  of  the  ascend- 
ing filaments  of  the  cervical  plexus.  The  branches  which 


508 


BLOOD-VESSELS  OF  THE  NECK. 


enter  into  the  external  jugular,  besides  the  temporal  and 
internal   maxillary,  are   the   occipital,   posterior   cervical 
FIG.  154.  cutaneous,  and  the  posterior  and 

supra  scapular  reins,  the  last  of 
which  joins  it  at  its  termination. 
This  vein  communicates  with 
the  internal  jugular,  generally 
at  its  upper  part,  and  in  its 
descent  with  the  anterior  jugu- 
lar. It  is,  however,  very  varia- 
ble, being  sometimes  double  and 
very  small.  It  returns  the 
blood  from  the  external  parts  of 
the  head,  integuments  and  su- 
perficial muscles  of  the  neck. 

The  internal  jugular  vein  is 
the  great  channel  receiving  the 
blood  of  the  sinuses  already 
noticed  in  the  account  of  the  brain.  It  commences  at  the 
foramen  lacerum  posterius,  where  the  lateral  sinuses  ter- 
minate, then  descends  the  neck  first  on  the  outside  of  and  a 
little  behind  the  internal  carotid,  then  on  the  outside  of  the 
common  carotid  artery  to  the  root  of  the  neck,  where  it 
joins  with  the  subclavian  to  form  the  vena  innominata  of 
each  side — at  its  superior  portion  the  ninth  and  eighth  pair 
of  nerves  are  on  its  inside,  and  the  styloid  process  with  its 
muscles  are  in  front.  The  lingual  and  glosso-pharyngeal 
nerves  are  between  this  vein  and  the  artery  a  little  lower 
down,  while  the  spinal  accessory  passes  behind  in  its  out- 
ward direction.  The  rest  of  the  course  of  this  vein  is 
enclosed  in  the  same  sheath  with  the  common  carotid 
artery  and  pneumogastric  nerve,  receiving  in  its  descent 
the  facial,  lingual,  pharyngeal,  and  thyroid  veins,  and 
communicating  freely  with  the  external  jugular. 

FIG.  154  represents  the  Veins  of  the  Neck  and  Head,  a  Frontal  vein. 
6  Nasal  vein,  c  Supra  orbital,  d  Angular  vein,  e  Facial  vein.  /  Superfi- 
cial temporal  veins,  g  Middle  temporal,  h  Masseteric  plexus  of  veins. 
i  Occipital  veins,  j  External  jugular,  k  Internal  jugular.  I  Anterior  jugu- 
Jar  m  Scapular  veins,  n  Subclavian  vein,  o  Vena  innominata. 


NERVES  OF  THE  NECK.  509 

The  anterior  jugular,  called  also  superficial  thyroid  vein, 
begins  at  the  os-hyoides,  and  descends  along  the  anterior 
margin  of  the  sterno-mastoideus,  near  the  median  line  of 
the  neck,  covered  by  the  superficial  cervical  fascia,  and  ter- 
minates below,  either  in  the  external  jugular  or  subclavian 
veins.  The  two  anterior  jugulars  often  connect  by  a  trans- 
verse branch  and  frequently  communicate  above  with  the 
facial,  internal,  and  external  jugular  veins.  They  also 
vary  much  in  size  and  return  the  blood  from  the  superficial 
parts  on  the  front  of  the  neck. 

The  subclavian  veins  are  continuations  of  the  axillary, 
anc}.  are  situated  beneath  the  clavicle  and  subclavius  mus- 
cle. Passing  over  the  first  rib,  in  front  of  the  subclavian 
artery,  and  crossing  the  scalenus  anticus  muscle,  they  ter- 
minate by  uniting  with  the  internal  jugular,  to  form  the 
right  and  left  vena  innominata,  which  also  unite  to  consti- 
tute the  superior  vena  cava.  The  subclavian  veins  receive 
the  tributary  streams  of  the  external  jugular  veins,  the  ver- 
tebral, inferior  thyroid,  inferior  laryngeal,  internal  mammary, 
and  superior  intercostal — though  these  latter  frequently 
empty  into  the  vena  innominata. 

SECTION   V. 


These  are  the  par  vagum,  spinal  accessory,  lingual,  fa- 
cial, cervical  plexus  and  phrenic  nerve,  brachial  plexus, 
sympathetic  nerve  and  its  ganglia. 

The  par  vagum  (Fig.  152)  has  been  already  fully  de- 
scribed under  the  head  of  organs  of  deglutition  in  the  neck, 
which  see. 

The  spinal  accessory  nerve,  (Fig.  153,)  or  third  division  of 
the  eighth  pair,  called  the  superior  respiratory  nerve  of  Sir 
Charles  Bell,  arises  as  low  down  in  the  neck  as  the  fourth 
or  fifth  cervical  vertebra,  by  several  filaments  from  the  res- 
piratory tract,  between  the  anterior  and  posterior  spinal 
roots;  it  ascends  behind  the  ligamentum  denticulatum,  tp 
the  base  of  the  cranium,  passes  through  the  foramen  mag- 


510  NERVES  OF  THE  NECK. 

num.  and  joins  the  other  divisions  of  the  eighth  pair, 
along  with  which,  and  enclosed  in  the  same  sheath,  it 
passes  through  the  foramen  lacerum  posticus,  and  thence 
to  the  muscles  on  the  side  of  the  neck. 

In  the  foramen  lacerum  it  is  connected  to  the  vagus  by 
one  or  more  filaments.  On  the  outside  of  the  foramen  it 
divides  itself  into  two  branches — internal  and  external.  The 
former  is  the  smaller  and  joins  the  pneumogastric,  while 
the  external  is  the  continuation  of  the  accessory  nerve, 
which  proceeds  outward,  behind  the  internal  jugular  vein, 
to  the  sterno-mastoid  muscle,  the  upper  third  of  which  it 
perforates  and  supplies  with  filaments,  anastomosing  with 
the  second,  third,  and  fourth  cervical  nerves,  and  finally 
being  distributed  upon  the  trapezius  as  low  down  as  the 
scapula. 

The  function  of  this  nerve  is  regarded  as  purely  motor, 
though  the  observations  of  Todd  and  Bowman  assign  sen- 
sation to  the  fibres  of  the  internal  branch.  This  nerve, 
along  with  the  pneumogastric,  has  been  compared  to  a  com- 
pound or  spinal  nerve,  the  spinal  accessory  being  the  motor, 
while  the  vagus,  with  its  ganglia,  represents  the  sensory. 

TJie  lingual,  liypoglossal,  or  ninth  pair  of  nerves,  (Fig.  91.) 
This  nerve  is  the  motor  nerve  to  the  tongue,  as  well  as  to 
several  structures  at  the  superior  part  of  the  neck.  It 
arises  from  the  medulla  oblongata  between  the  corpus  pyr- 
amidale  and  corpus  olivare,  by  six  or  ten  filaments,  which, 
uniting  together,  pass  out  of  the  cranium  through  the  an- 
terior condyloid  foramen  of  the  occipital  bone.  It  then 
proceeds  forward,  between  the  internal  jugular  vein,  and 
internal  carotid  artery,  ascending  with  the  vein  as  low  as 
the  angle  of  the  jaw,  when  it  curves  across  the  occipital 
branch  of  the  external  carotid,  taking  the  course  of  the 
digastric  muscle  and  lingual  artery,  to  the  base  of  the 
tongue  above  the  os-hyoides ;  here  it  passes  above  the 
mylo-lm)ides,  crossing  the  hyo-glossus,  and  dividing  into 
filaments  which  supply  these  muscles,  the  genio-hyo-glos- 
sus  and  the  lingualis,  and  continued  forward  through  the 
tongue  as  far  as  its  tip. 


NERVES  OF  THE  NECK.  511 

The  branches  of  this  nerve  are,  first,  those  which  com- 
municate, on  the  outside  of  the  condyloid  foramen,  with 
the  pneumogastric,  sympathetic,  spinal  accessory,  and  first 
and  second  cervical  nerves.  As  it  crosses  the  occipital 
artery  it  sends  off  the  descendens-noni,  which  descends 
in  front  of  and  outside  the  sheath  of  the  common  caro- 
tid artery,  to  the  middle  of  the  neck,  where  it  meets 
with  branches  from  the  second  and  third  cervical  nerves, 
forming  a  plexus  which  is  distributed  upon  the  sterno- 
hyoid,  thyroid,  and  omo-hyoid  muscles.  About  the  os-hy- 
oides,  filaments  of  the  lingual  have  been  traced  to  the 
constrictors  of  the  pharynx,  stylo-pharyngeus,  and  thyro- 
hyoid  muscles ;  and  on  the  hyo-glossus,  communicating 
branches  form  a  plexus  with  the  gustatory  branch  of  the 
fifth  pair. 

The  facial  nerve  is  described  under  the  organs  of  expres- 
sion, to  which  the  reader  is  referred. 

The  cervical  plexus  (Fig.  153)  is  divided  into  the  anterior 
B,nd.  posterior  cervical  plexuses.  The  former  is  formed  by  the 
union  of  the  anterior  branches  of  the  four  superior  cervical 
nerves,  and  is  situated  upon  the  side  of  the  neck,  between 
the  trapezius  and  sterno-mastoid  muscles,  corresponding  to 
the  second,  third,  and  fourth  vertebra?,  and  covered  by  the 
platysma  and  fascia.  This  plexus  rests  upon  the  origin  of 
the  splenius  and  levator  anguli  scapulas  muscles,  and  com- 
municates with  the  eighth  and  ninth  nerves,  and  the  su- 
perior cervical  ganglion  of  the  sympathetic.  Its  branches 
are  divided  into  ascending  and  descending,  and  these  again 
into  superficial  and  deep. 

The  superficial  consist  of — Superficialis  colli,  Auricu- 
laris  magnus,  and  Occipital. 

The  superficialis  colli  comes  from  the  second  and  third 
cervical  nerves,  winds  round  the  mastoid  muscle,  and  as- 
cends, along  with  the  external  jugular  vein,  to  the  angle 
of  the  jaw.  supplying  filaments  to  the  lower  part  of  the 
face,  and  to  the  integuments  of  the  lateral  and  anterior 
regions  of  the  neck,  and  connecting  with  the  cervico-facial. 

The   auricularis  magnus   comes   also  from  the  second 


512  NERVES  OF  THE  NECK. 

and  third  cervical  nerves,  is  larger  than  the  last,  and 
ascends  hehind  the  mastoid  muscle,  to  the  parotid  gland, 
where  it  divides  into  a  superficial  branch,  supplying  the 
integument  over  the  parotid  gland  and  anterior  ear,  and  a 
deep  one  which  enters  the  lower  part  of  the  gland,  passes 
over  the  mastoid  process,  and  is  distributed  to  the  back  of 
the  ear,  and  side  and  back  of  the  scalp,  and  communicating 
with  the  facial  and  occipital  nerves. 

The  occipitalis  minor  arises  from  the  second  cervical,  and 
proceeds  upward,  behind  the  mastoid  muscle,  to  supply  the 
skin  of  the  back  part  of  the  head,  and  the  occipital  part  of 
the  occipito-frontalis  muscle. 

The  descending  brandies  of  the  cervical  plexus  are  divided 
into  superficial  and  deep.  The  former  consist  of  external, 
middle,  and  internal  branches,  which,  supply  the  integu- 
ments upon  the  sides  of  the  neck,  and  extend  down  upon 
the  pectoral  and  deltoid  muscles. 

The  deep  descending  branches  consist  of  the  muscular,  the 
communicating,  and  the  phrenic. 

The  muscular  supply  the  trapezius,  levator  anguli  sea- 
pulse,  and  sterno-mastoid  muscles,  and  come  from  different 
parts  of  the  plexus. 

The  communicating  connect  with  the  sympathetic,  pneu- 
mo-gastric,  and  lingual  nerves  near  the  base  of  the  cranium, 
and  in  front  of  the  atlas. 

A  nerve  called  the  communicans  noni,  is  a  long,  delicate 
branch,  coming  from  the  second  and  third  cervical  nerves, 
which  descends  generally  in  front  of  the  sheath  of  the  cer- 
vical vessels,  though  sometimes  on  the  outside  of  the  inter- 
nal jugular  vein,  and  occasionally  behind  it,  to  the  middle 
tendon  of  the  omo-hyoid,  where  it  unites  in  the  form  of  a 
loop,  with  the  descendens  noni. 

The  phrenic  is  a  very  important  nerve,  and  is  the  internal 
respiratory  of  Sir  Charles  Bell.  It  arises  from  the  third 
and  fourth  cervical  nerves,  with  additional  filaments  from 
the  fifth  and  sixth,  and  sometimes  from  the  seventh,  con- 
necting with  the  sympathetic.  It  descends  in  front  of  the 
scalenus  anticus  muscle,  and  at  the  root  of  the  neck  com- 


NERVES  OF  THE  NECK.  613 

municates  with  the  inferior  cervical  ganglion,  and  fre- 
quently with  the  vagus  and  its  recurrent  branch ;  at  this 
point  it  enters  the  chest  between  the  subclavian  artery  and 
vein,  and  proceeds  downward  on  the  side  of  the  pericardium 
in  the  middle  mediastinum,  to  the  diaphragm,  to  which  it 
is  distributed,  sending  branches  on  the  right  side  to  the 
liver  and  vena  cava,  and  on  the  left  to  the  oesophagus  and 
stomach.  The  left  phrenic  is  longer  than  the  right  from 
the  direction  of  the  heart  to  the  left  side.  It  has  been  com- 
monly considered  to  be  a  purely  motor  nerve,  but  Laschka's 
recent  researches  show  that  it  contains  sensory  filaments 
also.  He  states  that  it  effects  a  double  interchange  between 
the  spinal  and  the  sympathetic  nerves.  It  commonly  arises 
only  from  the  fourth  cervical  nerve.  The  diaphragmatic 
branches  go  to  the  tendinous  centre,  the  inferior  cava,  the 
right  auricle,  and  the  liver. 

The  posterior  cervical  plexus  is  formed  by  the  junction  of 
the  posterior  branches  of  the  first,  second  and  third  cervical 
nerves.  It  is  situated  beneath  the  complexus.  Its  branches 
are  called  musculo-cutaneous  and  occipitalis  major. 

The  musculo  cutaneous  supplies  the  complexus  and  semi- 
spinalis  colli,  and  then  passes  through  the  trapezius  to 
become  cutaneous,  being  distributed  to  the  integuments  on 
the  back  of  the  neck  and  head. 

The  occipitalis  major  comes  from  the  second  cervical  nerve, 
takes  the  course  of  the  occipital  artery,  and  supplies  the 
muscles  on  the  back  part  of  the  neck  and  head.  The  pos- 
terior branches  of  the  lower  cervical  nerves  supply  the  mus- 
cles and  integuments  on  the  lower  and  back  part  of  the 
neck  and  head. 

The  bracliial  plexus  (Fig.  153)  is  situated  at  the  lower 
part  of  the  neck  in  the  posterior,  inferior,  lateral  triangle, 
above  the  clavicle,  and  between  the  mastoid  and  posterior 
belly  of  the  digastric  muscles.  It  is  formed  by  the  union 
of  the  four  inferior  cervical  and  first  dorsal  nerves:  the  fifth 
and  sixth  unite  into  one  trunk  ;  the  eighth  cervical  and 
first  dorsal  also  unite  into  one  trunk ;  the  seventh  cervical 
stands  alone  for  some  distance,  so  that  this  plexus  presents 
33 


514  NERVES  OF  THE  NECK. 

at  first  three  roots,  which  again  divide  and  unite  in  a 
variety  of  ways  to  constitute  this  plexus.  Its  lower  part 
receives  the  name  of  axillary  plexus.  This  plexus  commu- 
nicates with  the  cervical  by  means  of  a  filament  from  the 
fourth  cervical  nerve.  In  the  neck  it  passes  between  the 
scalenus  anticus  and  medius  muscles,  above  and  outside 
of  the  subclavian  artery,  under  the  clavicle  and  sub-cla- 
vian  muscle,  over  '  the  first  rib  to  the  axilla,  where  the 
branches  of  this  plexus  so  interlace  as  completely  to  sur- 
round the  axillary  artery  from  the  clavicle  to  the  head  of 
the  humerus. 

The  brachial  plexus  is  very  extensive,  and  sends  branches 
to  the  neck,  the  anterior  part  of  the  chest,  and  the  upper  ex- 
tremity. Only  those  going  to  the  neck  claim  our  attention 
in  this  place.  The  balance  of  this  plexus  will  be  consid- 
ered in  its  appropriate  relations  with  the  organs  of  the 
chest  and  superior  extremity. 

The  branches  supplying  the  neck  are  termed  supra  clavic- 
ular, and  go  to  the  subclavian  muscle,  the  scaleni,  levator 
anguli  scapulae,  and  rhomboid  muscles. 

The  posterior  thoracic,  called  also  the  external  respiratory 
nerve  of  Mr.  Bell,  arises  from  the  fourth,  fifth  and  sixth 
cervical  nerves,  passes  downward  and  outward,  behind  the 
brachial  plexus  and  vessels,  upon  the  scalenus  posticus, 
and  ultimately  terminates  in  the  great  serratus  muscle. 
This  is  a  very  long  nerve,  and  from  its  origin  so  near 
the  phrenic,  its  function,  according  to  Bell,  is  to  associate 
the  serratus  magnus  muscle  with  the  diaphragm  in  res- 
piration. 

Sympathetic  nerve  of  the  neck. — The  sympathetic  nerve  is 
so  called  from  its  extensive  relation  with  all  the  various 
parts  of  the  body,  connecting  the  several  organs  and  vis- 
cera, and  uniting  the  whole  in  one  harmonious  action  or 
series  of  actions.  It  is  also  styled  ganglionic,  from  the 
number  of  ganglia  which  occur  upon  it.  By  Bichat  it 
was  named  the  nervous  system  of  organic  life — in  con- 
tradistinction to  the  cerebro-spinal  or  nervous  system  of 
animal  life.  Other  terms,  as  the  intercostal,  splanchnic, 


NERVES  OP  THE  NECK. 


515 


FIG.  155. 


and  automatic,  have  all  been  applied 
to  it. 

The  sympathetic  is  not  a  single 
nerve,  hut  consists  of  two  cords  extend- 
ing from  the  hase  of  the  cranium  to 
the  coccyx.  Each  of  these  cords  de- 
scends along  the  neck  anterior  to  the 
vertebras,  behind  the  carotid  artery 
and  jugular  vein,  and  in  front  of  the 
rectus-capitis  and  longus  colli  muscles. 
In  the  chest  they  are  traced  along  the 
sides  of  the  spine,  over  the  heads  of 
the  several  ribs,  and  are  found  enter- 
ing the  abdomen  beneath  the  true  lig- 
amentum  arcuatum.  They  descend  on 
the  anterior  part  of  the  lumbar  ver- 
tebras, between  the  psoas  muscles  and 
crura  of  the  diaphragm,  into  the  pel- 
vis ;  they  pass  along  the  anterior  sur- 
face of  the  sacrum  to  the  first  bone 
of  the  coccyx,  where  the  two  cords 
unite  in  a  small  ganglion,  called  coc- 
cygeal  or  ganglion  impar. 

Throughout  the  whole  course  of 
these  nerves  a  series  of  knots  or  ganglia 
are  observed,  named  according  to  their  situation,  cervical, 
dorsal,  lumbar,  and  sacral;  there  being  three  cervical, 
twelve  dorsal,  five  lumbar,  and  three  sacral. 

FIG.  155  represents  the  Sympathetic  Nerve  its  entire  length.  1  Superior 
cervical  ganglion.  2  Its  ascending  branch.  3  Descending  branch.  4  Exter- 
nal branches  connecting  with  the  first,  second  and  third  cervical  nerves.  5 
Internal  branches  connecting  with  the  eighth,  ninth  and  facial  nerves.  6  Su- 
perior cardiac  nerve.  7  Middle  cardiac  nerve.  8  Inferior  cardiac  nerve, 
coming  successively  from  the  first,  second  and  third  cervical  ganglia.  9  First 
dorsal  ganglion.  10  Last  dorsal  ganglion.  11  Spinal  nerves.  12  Great 
splanchnic  nerve.  13  Semilunar  glangia  forming  the  solar  plexus.  14  Lesser 
splanchnic  nerve,  going  to  the  renal  plexus.  15  Branches  from  the  lumbar 
ganglia.  16  Hypogastric  plexus.  17  Sacral  ganglia.  18  Ganglion  impar  or 
last  ganglion  of  the  sympathetic. 


516  GANGLIA  OF  THE  HEAD. 

From  these  ganglia  an  immense  number  of  "branches 
radiate  in  every  direction,  constituting  so  many  plexuses. 
The  plexuses  follow  the  course  of  the  several  arteries,  re- 
ceiving the  names  of  the  respective  vessels  they  pursue,  aa 
the  hepatic,  gastric,  splenic,  renal,  &c.  In  many  in- 
stances they  form  complete  nervous  sheaths  around  the 
vessels. 

The  sympathetic  cords,  it  will  be  observed,  in  their  de- 
scent along  the  spinal  column,  connect  with  all  the  spinal 
nerves  by  one  or  two  filaments — with  the  cervical  gene- 
rally by  one,  and  with  the  dorsal,  lumbar,  and  sacral  by 
two.  At  their  superior  extremity  they  also  communicate 
with  all  the  cerebral  nerves  as  they  emerge  from  the  cra- 
nium, except  the  fourth  and  sixth  pair,  and  with  these  they 
unite  in  the  cavernous  sinus;  while  with  the  olfactory, 
optic,  and  auditory,  the  union  occurs  in  their  ultimate  ex- 
pansion. There  is  also  a  communication  of  the  sympathetic 
nerves  with  the  several  ganglia  of  the  head,  which  gan- 
glia are  regarded  as  the  same  with  the  rest  of  the  gan- 
glionic  system.  And  though  they  have  been  described 
along  with  the  several  organs  of  the  head,  yet  for  the  pur- 
pose of  having  a  connected  view  of  the  whole  we  introduce 
the  following  summary  and  figure  (156.) 

Six  sympathetic  ganglia  are  found  belonging  to  the 
head,  as  follows : 

The  ganglion  of  Eibes,  named  after  its  discoverer,  and 
situated  upon  the  anterior  communicating  artery.  This 
ganglion  is  the  point  of  junction  of  the  sympathetic  cords 
of  the  opposite  sides  of  the  body,  at  their  superior  part.  It 
sends  filaments  to  the  carotid  plexus. 

The  lenticular ,  ciliary  or  ophthalmic  ganglion,  is  situated 
within  the  orbit,  on  the  outside,  and  in  close  contact  with 
the  optic  nerve,  and  imbedded  in  a  quantity  of  fatty  mat- 
ter. It  is  a  small,  flattened  and  grayish  body,  sending  off 
the  ciliary  nerves  to  the  eye,  and,  according  to  Tiedemann, 
a  filament  along  with  the  arteria  centralis  retina.  It 
communicates^with  the  nasal  branch  of  the  ophthalmic, 
with  the  third  or  motor  oculi,  and  with  the  carotid  plexus 


GANGLIA  OF  THE  HEAD. 


61T 


"by  a  long  fil- 
ament going 
backward  to 
the  cavern- 
ous sinus. 

The  spTie- 
no-palatine, 
or  ganglion  of 
Meckely  is  sit- 
uated in  the 
spheno-max- 
illary  fossa, 
in  a  quanti- 
ty of  fat  sur- 
rounded  by 

branches  of  the  internal  maxillary  artery,  and  presents 
a  reddish  triangular  appearance.  It  gives  off  three  sets  of 
branches  internal  or  nasal,  descending  or  palatine,  and  pos- 
terior or  Vidian — all  of  which  have  been  described  with  the 
superior  maxillary  nerve,  under  the  head  of  active  organs 
of  mastication.  This  ganglion  of  Meckel,  by  means  of  its 
Vidian  nerve,  which  takes  a  most  circuitous  and  lengthy 
route,  as  already  described,  establishes  a  communication 
with  the  carotid  plexus,  and  through  this  latter  with  the 
superior  cervical  ganglion — with  the  glosso-pharyngeal  and 
pneumogastric,  by  its  tympanic  branch,  with  the  facial, 
superior,  and  inferior  maxillary  nerves,  and  with  the  sub- 
maxillary  ganglion. 

The  sub-maxillary  ganglion  is  in  contact  with  the  sub- 

Fio.  156  represents  the  Cranial  Ganglia  of  the  Sympathetic  Nerve,  o  Gan- 
glion of  Ribes.  6  Filament  connecting  with  the  carotid  plexus  c.  d  Lenticu- 
lar ganglion  e  Third  nerve  getting  a  filament  from  the  ganglion.  /  Nasal 
nerve  also  getting  a  filament  from  the  ganglion,  g  A  sympathetic  filament 
going  to  carotid  plexus,  h  Sixth  nerve  in  cavernous  sinus,  getting  two  fila- 
ments from  carotid  plexus  i  Spheno-palatine  or  Meckel's  ganglion,  j 
Branches  connecting  with  superior  maxillary  nerve,  fc  Palatine  or  descend- 
ing branches.  I  Spheno  palatine  or  nasal  branches,  m  Naso  palatine,  a 
branch  of  the  latter,  n  Vidian  or  pterygoid  nerve,  o  Its  carotid  branch, 
p  Petrosal  branch,  q  Facial  nerve,  r  Chorda-tympani.  s  Gustatory  nerve. 
I  Submaxillary  ganglion,  u  Superior  cervical  ganglion  of  the  sympathetic. 


518  GANGLIA  OF  THE  HEAD. 

maxillary  gland,  is  of  small  size,  and  communicates  with 
the  gustatory  and  lingual  nerves,  and  with  the  sympa- 
thetic filaments  of  the  facial  artery,  also,  through  the 
Vidian  nerve,  with  the  carotid  plexus  and  the  rest  of  the 
cranial  ganglia. 

The  otic-ganglion  (or  ganglion  of  Arnold)  is  found, 
directly  below  the  foramen  ovale,  on  the  inside  of  the  in- 
ferior maxillary  nerve,  upon  the  outside  of  the  Eustachian 
tube,  and  anterior  to  the  middle  meningeal  artery.  It  is 
a  small,  not  very  distinct,  and  reddish  body,  distributing 
filaments  to  the  tensor  palati  and  tensor  tympani  muscles, 
and  communicating,  by  its  branches,  with  both  the  motor 
and  sentient  portions  of  the  inferior  maxillary,  and  with 
the  facial  and  tympanic  branches  of  the  glosso-pharyn- 
geal. 

The  naso-palatine  or  ganglion  of  Cloquet. — The  existence 
of  this  body  as  a  proper  ganglion  has  been  doubted.  It  is 
very  small,  and  when  present,  found  in  the  foramen  inci- 
sivum,  distributing  branches  to  the  anterior  palate,  and 
communicating  with  the  ganglion  of  Meckel,  by  means  of 
the  internal  nasal  branch  passing  off  from  this  latter  gang- 
lion and  going  to  the  ganglion  of  Cloquet. 

.Ganglion  of  Laumonier — (Fig.  157.)  —  This  ganglion, 
named  after  its  discoverer,  is  generally  seen  on  the  under 
surface  of  the  carotid  artery,  within  the  carotid  canal, 
though  sometimes  found  in  the  cavernous  sinus.  It  is 
small,  and  appears  to  be  an  expansion  of  the  petrosal  nerve 
before  joining  the  carotid  plexus,  and  is  also  called  the 
ganglion  caroticum,  or  cavernosum. 

It  is  represented  as  a  flattened,  elongated  ganglion,  form- 
ing the  connecting  link  between  the  cranial  and  extra- 
cranial  portions  of  the  sympathetic. 

A  variety  of  opinions  are  entertained  as  to  the  origin 
of  the  sympathetic.  Some  say  it  arises  in  the  brain ; 
others,  along  the  course  of  the  spinal  marrow,  and  its 
coccygeal  extremity;  while  others,  more  recently,  place 
its  origin  in  the  lining  coat  of  the  arteries. 

Those  who  assert  its  origin  from  the  brain,  say  it   is 


SYMPATHETIC  NERVE. 


519 


by  the  union  of  the  [Fio.  157. 

Vidian  hranch  of  the 
fifth  and  sixth  pair 
of  nerves,  whose  di- 
verse properties  com- 
ing together,  consti- 
tute, as  it  were,  a 
tertium  quid,  styled 
the  sympathetic. 
This  view  is  ex- 
plained by  the  ac- 
companying figure, 
from  Lobstein. 

The  latter  opinion, 
which  places  the  or- 
igin in  the  interior 
of  the  arteries,  re- 
gards the  lining  coat 
of  these  vessels  as 
essentially  nervous, 
and  makes  the  semi- 
lunar  ganglion,  in 
the  abdomen,  the 
great  centre  of  this 
system.  Whatever 

may  be  its  origin,  there  is  strong  reason  for  believing,  with 
Bichat,  that  it  is  the  especial  nerve  or  system  of  nerves  for 
organic  life,  presiding  over  the  functions  of  involuntary 
motion,  as  digestion,  absorption,  circulation,  secretion — in 
a  word,  all  the  functions  of  nutrition.  There  are  also 

FIG.  157  represents  the  origin  of  the  Sympathetic  Nerve,  agreeably  to  Lob- 
stein,  a  a  Carotid  artery.  6  Ganglion  of  Laumonier.  c  From  this  latter 
ganglion  three  branches  are  sent  off  to  join  the  sixth  pair  of  nerves,  d  The 
sixth  nerve  separated  into  two  fasciculi,  e  The  superior  fasciculus.  /  The 
inferior  fasciculus  parted,  by  a  groove,  from  the  superior;  and  it  is  the  infe- 
rior which  unites  with  the  three  branches  from  the  ganglion,  g  Petrosal 
branch  of  Vidian  nerve  joining  the  ganglion,  h  Twig  of  the  latter  branch. 
i  t  Filaments  proceeding  from  the  ganglion  to  the  artery,  j  A  branch  going 
behind  the  carotid  from  the  ganglion,  k  A  branch  going  from  the  ganglion  in 
front  of  carotid,  dividing  it.  I  m  Sympathetic  nerve. w 


520  SYMPATHETIC  NERVE. 

reasons  for  believing  it  to  be  not  only  independent  of  the 
brain  and  spinal  marrow,  but  the  original  and  formative 
system  to  these  latter  portions  as  well  as  to  the  rest  of 
the  animal  body.*  Well  authenticated  cases  are  recorded 
of  the  absence  of  the  brain,  in  acephalous  foetuses  ;  and  still 
further,  of  the  whole  cerebro-spinal  system.  But  no  cases, 
we  believe,,  are  recorded  of  the  sympathetic  system  being 
"wanting,  which  seems  fairly  to  show  independence,  as  well 
as  priority  of  existence. 

The  sympathetic,  in  the  neck,  presents  three  ganglia, 
the  superior  cervical,  middle,  and  inferior  cervical,  (Fig.  155.) 

The  superior  cervical  ganglion  is  situated  upon  the  rec- 
tus  capitis  anticus,  on  the  inside  of  the  eighth  and  ninth 
pair  of  nerves,  and  behind  the  internal  carotid  artery  and 
jugular  vein.  It  is  of  an  oval  shape,  and  reddish  color,  ex* 
tending  from  the  first  cervical  vertebra,  about  half  an  inch 
below  the  carotid  foramen,  to  the  third. 

Its  branches  are — superior,  inferior,  internal,  external^ 
and  anterior.  The  superior,  two  in  number,  ascend  in  the 
carotid  canal,  where  they  form  the  carotid  plexus.  Here  a 
junction  with  the  Vidian  branch  of  the  fifth  and  the  sixth 
occurs,  and  from  this  point  filaments  are  traced  into  the 
cavernous  sinus,  constituting  the  cavernous  plexus,  and 
from  thence  to  the  Casserian  ganglion — also  to  the  lentic- 
ular ganglion,  while  others  are  found  accompanying  the 
ophthalmic  artery  and  its  branches. 

The  inferior  branch  forms  the  continued  trunk  of  the 
sympathetic,  which  connects  this  with  the  middle  or  lower 
cervical  ganglion. 

The  internal  branches  proceed  to  the  pharynx,  larynx, 
and  heart.  Those  of  the  pharynx  unite  with  the  glosso- 
pharyngeal  and  par  vagum,  forming  the  pharyngeal  plexus. 
The  laryngeal  unite  with  the  branches  of  the  superior  la- 
ryngeal  nerve,  while  the  cardiac  descend  the  neck,  behind 
the  sheath  of  the  common  carotid,  entering  the  chest,  along 

*  See  appendix  to  Sir  Wilson  Philip  on  "  acute  and  chronic  diseases,"  by 
James  H.  Miller,  M.  D.,  former  Professor  of  Anatomy  in  the  Washington 
Medical  College  of  Baltimore. 


GANGLIA  OF  THE  NECK.  521 

with  the  arteria  innominata  upon  the  right,  and  the  sub- 
clavian  artery  upon  the  left  side,  to  the  great  cardiac 
plexus. 

The  external  branches  unite  with  the  three  superior  cer- 
vical nerves,  and  with  the  lingual,  par  vagum,  and  glosso- 
pharyngeal. 

The  anterior  branches  are  called  by  Scarpa,  nervi  molles, 
from  their  soft  texture.  They  are  of  a  gray  color,  very 
numerous,  and  accompany  the  external  carotid  and  its 
branches,  forming  plexuses  around  each,  which  are  named 
according  to  the  artery  they  surround,  as  the  superior 
thyroid,  facial,  and  lingual  plexus. 

The  middle  cervical  ganglion  is  situated  upon  the  longus 
colli  muscle,  opposite  the  fifth  cervical  vertebra,  and  be- 
hind the  common  carotid  artery,  resting  upon  the  superior 
thyroid  artery.  It  is  smaller  than  the  superior,  of  irregu- 
lar form,  and  sometimes  wanting.  By  Haller  it  is  termed 
the  thyroid  ganglion.  It  sends  off  branches  which  ascend, 
descend,  pass  outward  and  inward,  and  communicate  with 
the  superior  and  inferior  cervical  ganglia,  with  the  vagus, 
and  fourth  and  fifth  cervical  nerves;  it  also  sends  down 
the  middle  or  great  cardiac  nerve  to  join  the  cardiac 
plexus. 

The  inferior  cervical  ganglion  is  situated  between  the 
neck  of  the  first  rib  and  the  transverse  process  of  the  last 
cervical  vertebra.  Instead  of  being  single,  it  sometimes 
consists  of  several  ganglia,  behind  and  on  either  side  of  the 
vertebral  artery.  It  also  radiates  branches  in  every  direc- 
tion. The  superior  conneqt  with  the  middle  cervical  gang- 
lion, and  a  considerable  number  ascend  along  with  the 
vertebral  artery,  forming  plexuses  around  it,  and  entering 
the  cranium  to  connect  with  the  carotid  plexus.  Its  external 
branches  unite  with  the  three  lower  cervical  and  first  dorsal 
nerves.  Its  inferior  go  before  and  behind  the  subclavian 
artery  to  unite  with  the  first  thoracic  ganglia,  and  from 
its  interior,  the  inferior  cardiac  nerve  descends  to  the  cardiac 
plexus,  connecting  with  the  vagus  and  recurrent.  Fila- 
ments also  pass  from  the  inferior  cervical  ganglion  to  the 


522  FASCIA  OF  THE  NECK. 

phrenic  nerve  and  brachial  plexus.  The  rest  of  the  sym- 
pathetic will  be  examined  in  connection  with  the  abdomi- 
nal and  thoracic  organs. 

SECTION  VI. 

THE  FASCLE  OF  THE  NECK. — (CERVICAL  FASCLE.) 

The  fasciae  of  the  neck  are  divided  into  the  superficial 
and  deep  cervical. 

The  superficial  cervical  fascia  is  situated  immediately 
beneath  the  integuments,  enclosing  the  platysma  myoides, 
and  sometimes  so  closely  connected  to  this  muscle,  as  to  be 
with  difficulty  separated  from  it.  It  is  continuous  with  the 
superficial  fascia  of  the  abdomen  and  chest,  and  attached 
to  the  sternum  and  clavicle.  It  is  traced  over  the  lateral 
and  anterior  parts  of  the  neck,  ascending  to  the  jaw  with 
which  it  is  connected,  and  expanding  over  the  parotid 
and  sub-maxillary  glands,  it  sends  processes  into  the  sub- 
stance which  surrounds  their  several  lobules.  It  then  pro- 
ceeds upward  to  form  a  strong  attachment  to  the  cartilage 
of  the  ear,  mastoid  process,  and  zygoma.  It  forms  the  an- 
terior layer  of  the  sterno-mastoid,  becomes  weak  at  the 
lateral  and  posterior  portions  of  the  neck,  gives  a  covering 
in  front  and  behind  to  the  trapezius,  and  is  traced  into  the 
fascia  profunda  or  deep  cervical  fascia. 

Indeed,  this  latter  fascia  is  regarded  as  nothing  more  than 
the  reflected  portion  of  the  deep  surface  of  the  superficial 
cervical,  and,  so  considered,  it  is  found  to  pass  from  the  su- 
perficial along  the  anterior  margin  of  the  sterno-mastoid,  go- 
ing behind  this  muscle,  the  omo-hyoid  and  trapezius,  back 
to  the  ligamentum  nuchae,  which  some  regard  as  its  origin. 
In  front  it  is  connected  to  the  larynx  and  thyroid  gland, 
invests  the  sterno-hyoid  and  sterno-thyroid  muscles,  forms 
sheaths  for  the  other  muscles,  as  well  for  the  vessels  and 
nerves,  and  at  the  inferior  part  of  the  neck  is  attached  to 
the  inter-clavicular  ligament  and  upper  posterior  margin 
of  the  sternum,  adjacent  to  the  clavicle  and  first  rib.  At 
this  point,  the  root  of  the  neck,  some  loose  fatty  matter  is 


GLANDS  OF  THE  NECK.  523 

found  between  the  superficial  and  deep  cervical  fascia. 
Between  the  trapezius  and  sterno-mastoid,  the  deep  cervical 
fascia  presents  the  cellular  appearance.  At  the  angle  and 
base  of  the  jaw  to  which  it  is  connected,  it  dips  down  deep 
to  be  attached  to  the  styloid  process,  forming  the  stylo- 
maxillary  ligament,  and  the  partition  between  the  parotid 
and  sub-maxillary  glands.  At  this  superior  part  we  find 
the  two  cervical  fascise  enclosing  the  parotid,  absorbent 
glands,  and  considerable  cellular  structure.  Hence,  when 
inflammation  is  set  up,  and  matter  is  formed,  from  the  un- 
yielding and  resisting  nature  of  these  fasciae,  the  suffering 
is  increased,  and  the  function  of  deglutition,  together  with 
the  movements  of  the  jaw  materially  interrupted. 

The  uses  of  the  cervical  fasciae  are  to  confine  and  support 
the  several  muscles,  vessels,  and  glands ;  and  at  the  lower 
part  of  the  neck,  according  to  the  experiments  of  Mr.  Law- 
rence, to  protect  the  trachea  from  the  pressure  of  the  atmos- 
phere during  inspiration. 

Lymphatic  Glands  of  the  Neck,  (cervical  glands) — The 
lymphatic  glands  belong  to  the  conglobate  division,  and 
form  part  of  the  absorbent  system.  This  system  performs 
the  function  of  absorption,  and  consists  of  the  lacteals,  lym- 
phatic vessels,  and  lymphatic  glands.  The  glands  have 
already  been  summarily  described  under  the  head  of  the 
glandular  tissue.  It  is  only  necessary  for  us  here,  there- 
fore, briefly  to  recapitulate  the  lymphatic  or  cervical  glands 
of  the  neck. 

These  are  divided  into  the  superficial  and  deep.  The 
former  are  seen  along  the  posterior  margin  of  the  sterno- 
cleido-mastoideus,  lying  scattered  between  this  muscle  and 
the  trapezius,  and  in  connection  with  the  external  jugu- 
lar vein.  The  deep  glands  are  large  and  numerous  and  form 
a  chain  descending  tbe  neck,  in  company  with  the  carotid 
vessels,  from  the  angle  of  the  jaw  to  the  chest.  They  are 
also  connected  with  the  pharynx,  oesophagus,  larynx,  and 
thyroid  gland,  and  with  the  glands  of  the  face  above  and 
the  thorax  below.  Through  both  the  superficial  and  deep 
get  of  glands,  the  lymphatics  of  the  head  and  neck  pass. 


624  GLANDS  OF  THE  NECK. 

Thyroid  Gland. — This  gland  is  situated  upon  the  sides  of 
the  larynx  and  upper  rings  of  the  trachea.  It  is  large,  and 
consists  of  two  portions  lying  laterally,  and  connected 
across  the  upper  part  of  the  trachea  by  a  middle  portion 
called  the  isthmus.  The  lateral  parts  are  termed  lobes. 
This  gland  is  of  a  reddish  brown  color,  deeper  in  the  child 
than  in  the  adult,  and  in  the  female  than  the  male.  Its 
consistence  is  soft.  ••>'$'  ' 

The  lobes  are  prominent  and  convex,  being  covered  by 
the  sterno-hyoid,  thyroid,  and  omo-hyoid  muscles,  pla- 
tysma,  fascia,  and  skin,  tying  along  the  side  of  the  trachea 
and  larynx,  ascending  as  high  as  the  thyroid  cartilage, 
and  connected  occasionally  to  the  base  of  the  os-hyoides, 
by  a  slip  which  is  thought  to  be  muscular,  and  called  by 
Soemmering  levator-glandulce,  though  its  muscular  char- 
acter is  doubted  by  others.  Upon  the  left  side,  the  lobe 
rests  upon  the  oesophagus,  both  right  and  left  lobes  cover 
the  carotid  artery,  inferior  thyroid  vessels,  and  recurrent 
nerve  on  either  side  of  the  neck. 

The  isthmus  or  middle  lobe  is  sometimes  wanting;  at 
other  times,  instead  of  passing  in  front  of  the  trachea,  it 
goes  behind  it,  •  and  then  rests  upon  the  oasophagus.  In 
this  case,  should  there  be  enlargement,  not  only  embarrass- 
ment, but  considerable  danger  to  both  respiration  and 
deglutition  might  be  the  result. 

The  thyroid  gland  consists  of  lobules,  which  are  again 
divisible  into  cells,  containing  a  yellow  serous  and  oily 
fluid,  according  to  some;  and  a  viscid,  transparent  secre- 
tion, according  to  others.  This  body  has  no  proper  capsule, 
unless  the  cellular  tissue  surrounding  it  be  regarded  as 
such.  It  has  no  excretory  duct,  and,  though  called  a 
gland,  can  have  no  claim  to  such  title  in  the  proper  sense 
of  the  term. 

It  is  largely  supplied  with  blood-vessels.  The  two  supe- 
rior thyroid  arteries  from  the  external  carotid,  go  to  it  from 
above,  and  the  two  inferior  thyroid  from  the  subclavian 
below.  The  corresponding  veins  are  distinguished  for  their 
size  and  number. 


THE  LARYNX.  525 

The  nerves  come  from  the  sympathetic  and  pneumo- 
gastric. 

The  lymphatics  pass  into  the  cervical  glands. 

The  thyroid,  in  the  infant,  descends  as  low  as  the  thy- 
mus  gland.  It  not  unfrequently  suffers  enlargement  con- 
stituting the  disease  called  goitre,  or  bronchocele. 

Its  function  is  yet  unsettled,  though  it  is  regarded  as  a 
diverticulum  to  the  cerebral  circulation. 

SECTION   VII. 

THE  LARYNX,   OR   ORGAN  OF  VOICE. 

The  larynx  is  situated  at  the  anterior  part  of  the  neck, 
between  the  tongue  and  trachea,  surmounting  the  respi- 
ratory tube,  and  thus  being  connected  with  the  organs  of 
respiration  below,  as  well  as  with  the  pharynx  or  that  of 
deglutition  above.  It  consists  of  cartilages,  ligaments,  mus- 
cles, vocal  chords,  a  lining  mucous  membrane  and  glands, 
with  blood-vessels,  and  nerves — thus  forming  a  great  vari- 
ety of  structures,  and  an  apparatus  both  curious  and  com- 
plicated. 

Cartilages. — The  cartilages  form  the  solid  frame  work,  and 
constitute  the  basis  of  'the  larynx.     They  are  five  in  num- 
ber, the  thyroid,  cricoid,  two  arytenoid,  and          p,Gt  153. 
epiglottis.    These,  united,  form  the  larynx, 
a  hollow  box  or  musical  case,  whose  cav- 
ity is  somewhat  quadrangular  and  larger 
above  than  below. 

The  thyroid  (0vp«oj,  shield,  «&>$,  like)  is 
the  largest  of  the  cartilages,  and  occupies  the  anterior 
and  lateral  portions  of  the  larynx.  It  consists  of  two  sym- 
metrical parts  called  alee,  which  meet  in  front  along  the 
median  line,  in  an  acute  angle  forming  a  prominence, 
known  under  the  name  of  pomum  Adami.  Each  ala  pre- 
sents a  broad  quadrilateral  plate  which  looks  backward, 
and  on  its  posterior  margin,  at  the  superior  and  inferior 

FIG.  158  represents  the  Thyroid  Cartilage,  a  Superior  cornu.  c  Inferior 
cornu.  6  Ala  of  left  side,  d  Entering  angle. 


526  THE  LARYNX. 

extremity  has  two  tubercles,  termed  the  superior  and  infe- 
rior cornua.  Each  ala  has  an  oblique  line,  dividing  it  into 
two  unequal  parts,  and  giving  attachment  to  the  sterno- 
thyroid,  thyro-hyoid,  and  inferior  constrictor  muscles  of 
the  pharynx.  The  superior  cornua  are  connected  by  liga- 
ments to  the  os-hyoides — the  inferior  are  articulated  with 
the  cricoid. 

The  thyroid  is  open  behind,  and  encloses  the  sides  of  the 
cricoid.  Its  posterior  surface,  behind  the  pomum,  is  concave 
and  has  attached  to  it  the  chordas-vocales,  and  epiglottic 
ligament. 

The  cricoid,  (*p«coj,  ring,  «So^  like,)  as  its  name  implies, 
is  annular  or  ring-like  in  its  form ;  it  is  situated  at  the 
lower  and  posterior  portion  of  the  larynx,  giving  that  pro- 
tection from  the  pressure  of  the  parts  behind,  which  the 
thyroid  does  from  that  of  the  atmosphere  in  front. 

It  is  narrow  before,  and  broad  and  vertical  behind.     Its 
anterior  surface  is  convex,  and  has  the  crico-thyroid  mus- 
FIG  159.      cles  attached  to  it.     The  posterior  surface  pre- 
sents   a    depression   for    the    crico-arytenoidei 
postici,  and  along  its  middle,  a  vertical  ridge 
giving  attachment  to  some  fibres  of  the  oeso- 
phagus.    The  upper  margin  is  horizontal,  and 
has  two  convex,  smooth  surfaces,  for  articulation  with  the 
bases  of  the  arytenoid  cartilages.     The  lower  margin  is 
circular,  and  connected  to  the  first  ring  of  the  trachea. 
The  arytenoid  cartilages  (apv^a^a,  a  pitcher)  occupy  a  ver- 
FIG.  160.      tical  position  upon  the  upper  and  posterior 
part  of  the  cricoid.     They  are  of  a  triangular 
shape,  and  are  two  in  number.     They  are  the 
smallest  in  size,  and  present  an  anterior  sur- 
face, which  is  convex  and  rough,  and  gives   attachment 
to   the  chordaz-vocales ;  a  posterior  surface,  which  is  con- 
cave, for  the  reception  of  the  arytenoid  -muscle ;  an  inter- 
nal surface,  which  is  flat,  smooth,  and  covered  by  mucous 
membrane,   where   the   two  arytenoids  approximate ;   an 

FIG.  159  represents  the  Cricoid  Cartilage. 

FIG.  160  represents  the  two  Arytenoid  Cartilages. 


THE  LARYNX.  527 

• 

inferior  surface,  which  is  also  smooth,  but  convex,  constitu- 
ting the  base,  and  articulating  with  the  cricoid ;  and  an 
upper  extremity,  or  apex,  which  is  surmounted  by  a  small 
movable  body,  called  the  appendix,  or  corniculum  laryngis, 
also  styled  tuberculum  Santorini. 

The  epiglottis— (e *v{wt  tj,  upon  the  tongue.) — This  cartilage 
is  situated  at  the  base  of  the  tongue,  and  is  a  fibro-cartila- 
ginous  structure.  It  occupies  nearly  a  vertical  position  at 
the  back  part  of  the  mouth.  Its  form  is  oval  FlG- 161» 
and  flattened,  having  its  edges  curved.  It  is  of  a 
yellowish  color,  pliable  and  elastic.  Its  surfaces 
are  anterior  and  posterior,  or  lingual  and  laryn- 
geal.  Both  surfaces,  as  well  as  the  edges,  are 
covered  by  mucous  membrane,  which,  in  front, 
is  loose,  and  constitutes  a  fold  called  the  fre. 
num  epiglottidis.  On  the  laryngeal  surface  this 
membrane  is  strongly  attached,  and  presents 
the  orifices  of  mucous  ducts,  and  when  removed 
shows  the  cartilage  itself  to  be  perforated.  It 
differs  from  the  other  cartilages  in  never  being  found  ossi- 
fied. It  is  so  nicely  adapted  to  the  superior  opening  of  the 
larynx,  as  completely  to  close  the  glottis  in  deglutition,  and 
thereby  guard  against  the  introduction  of  foreign  bodies, 
and  consequently  against  suffocation  in  the  act  of  respiration. 

Ligaments. — The  ligaments,  connecting  the  thyroid  car- 
tilage with  the  os-hyoides,  are  three  in  number — a  middle, 
the  ihyro-liyoid  membrane,  which  occupies  the  whole  space, 
extending  from  the  superior  edge  of  the  thyroid  cartilage, 
to  the  base  and  cornua  of  the  os-hyoides ;  and  two  lateral, 
the  thyro-hyoid,  extending  from  the  superior  cornua  of  the 
thyroid  cartilage,  to  the  extremities  of  the  cornua  of  the 
os-hyoides.  The  middle  ligament  is  a  strong  fibrous  expan- 
sion, giving  passage  to  the  superior  laryngeal  nerve  and 
artery.  The  lateral  consist  of  round  cords  sometimes  con- 
taining cartilaginous  or  osseous  grains. 

FIG.  161  represents  a  side  view  of  the  Epiglottis  Cartilage,  a  Front  of 
lingual  surface.  &  Posterior  or  pharyngeal  surface,  c  Upper  margin,  d 
Lower  margin  or  pedicle,  e  Lateral  portion. 


528  THE   LARYNX. 

« 

The  ligaments  connecting  the  thyroid  to  the  cricoid  are 
also  three  in  number,  a  middle  and  two  lateral. 

The  middle  crico-thyroid  is  a  strong,  yellow,  and  mem- 
branous ligament  attached  above  to  the  lower  edge  of  the 
thyroid,  and  below  into  the  upper  edge  of  the  cricoid  car- 
tilage. This  ligament  gives  passage  to  some  small  blood- 
vessels, and  is  interesting  from  being  the  place  of  selection 
for  the  operation  of  laryngotomy.  The  lateral  crico  thyroid 
ligaments  consist  of  the  capsular  and  synovial  membranes, 
forming  articulations  between  the  inferior  cornua  of  the 
thyroid  cartilage  and  the  sides  of  the  cricoid. 

The  arytenoid  cartilages  have  two  sets  of  ligaments — the 
one  connecting  them  with  the  cricoid,  called  the  crico- 
arytenoid — the  other  with  the  thyroid,  termed  the  thyro- 
arytenoid  ligaments.  The  first  set  consists  of  two  capsular 
ligaments  and  synovial  membranes,  by  which  the  base  of 
the  arytenoid  cartilages  articulate  with  the  superior  mar- 
gin of  the  cricoid.  This  articulation  allows  a  great  free- 
dom of  motion. 

The  second  set  comprises  four  ligaments,  two  superior, 
and  two  inferior.  The  former  are  sometimes  called  false 
ligaments,  as  they  consist  of  little  else  than  folds  of  mucous 
membrane,  containing  some  delicate  fasciculi  of  elastic 
fibres,  which  extend  from  the  inner  angle  of  the  thyroid 
to  the  anterior  face  of  the  arytenoid. 

The  inferior  thyro-arytenoid  ligaments  are  true  fibrous 
chords,  and  constitute  the  chordce  vocales.  They  extend 
from  the  inner  angle  of  the  thyroid,  horizontally  back- 
ward to  the  base  of  the  arytenoid  cartilage.  These  liga- 
ments are  strong,  and  consist  of  elastic  and  parallel  fibres 
which  are  associated  with  the  thyro-arytenoid  muscles,  and 
pursue  the  same  direction.  The  space  between  these  infe- 
rior ligaments  is  the  glottis  or  rima-glottidis. 

There  are  two  proper  ligaments  of  the  epiglottis,  the 
ihyro-epiglottideus  and  the  liyo-epiglottideus.  The  former 
extends  as  a  strong  chord  from  the  epiglottis  to  the  inner 
margin  of  the  thyroid  notch;  the  latter  is  seen  as  a  thin 
elastic  membrane  situated  below  the  base  of  the  os-hyoides 


MUSCLES  OF  THE  LARYNX.  529 

and  the  front  of  the  epiglottis.  The  folds  of  mucous  mem- 
brane connecting  the  epiglottis  to  the  base  of  the  tongue, 
have  also  been  called  ligaments — they  are  three  in  num- 
ber. The  middle  one,  called  the  frenum  epiglottidis ,  has  a 
few  elastic  fibres  and  some  cellular  tissue. 

Muscles  of  the  Larynx. — The  muscles  of  the  larynx  are 
nine  in  number,  eight  of  which  are  in  pairs. 

Dissection. — Make  the  same  in-  FIG.  162. 

cisions  as  for  the  anterior  neck, 
and  remove  the  platysma,  fascia, 
and  sterno-hyoideus,  and  sterno- 
thyroideus  muscles.  We  thus  ex- 
pose the  anterior  muscles  of  the 
larynx — which  are  the  thyro-hy- 
bideus  and  crico-thyroideus. 

The  tliyro-liyoideus  (Fig.  162)  is 
a  broad,  flat  muscle,  and  looks  very 
much  like  a  continuation  of  the 
sterno-thyroideus.  It  arises  from 
the  oblique  line  on  the  ala  of  the 
thyroid  cartilage,  ascends,  and  is  in-  a' 
serted  into  the  lower  margin  of  the 
corrm  of  the  os-hyoides  and  part 
of  its  base.  Its  function  is  to  raise 
the  larynx,  or  when  the  latter  is 
fixed  to  draw  down  the  os-hyoides. 

The  crico-thyroideus  (Fig.  162) 
is  a  short  muscle,  lying  below  the  last.  It  arises  from  the 
anterior  surface  of  the  cricoid  cartilage;  its  fibres  pass 
outward  and  upward,  to  be  inserted  into  the  inferior  mar- 
gin arid  cornu  of  the  thyroid. 

function. — To  bring  these  two  cartilages  towards  each 
other,  and  thus  shorten  the  vocal  case. 

On  the  lateral  and  posterior  portions  of  the  larynx  we 
have  the  tliyro~arytenoideus,,crico-arytenoideus  posticus,  crico- 
arytenoideus  lateralis,  arytenoideus  obliquus,  arytenoideus 

FIG.  162  represents  the  Muscles  in  front  of  the  Larynx,  a  Sterno  thy- 
roideus.  6  Crico-thyroideus.  c  Thyro-hyoideus.  d  Mylo-h\oideus. 

31 


530 


MUSCLES  OF  THE  LARYNX. 


transversus.     To  which  are  also  added  the  ihyro-epiglotti- 
deuSj  aryteno-epiglottideus. 

The   thyro-arytenoideus,   within   the   vocal   case,    arises 
near  the  angle  of  the  thyroid  cartilage  on  its  posterior  sur- 
FIG.  163.  face,  and  proceeds  backward  and  out- 

ward, along  the  sides  of  the  rima  glot- 
tidis,  to  be  inserted  into  the  anterior 
and  outer  margin  of  the  arytenoid  car- 
tilage.    Function. — To  bring  the  ary- 
tenoid   cartilages   forward,    and    thus 
relax  the  vocal  chords.     These  muscles 
are  regarded  as  the  most  important  in 
the  production  of  voice.     They  are  con- 
cealed by  the  alee  of  the  thyroid  car- 
tilage, and  are  connected  with  and  run 
along  the  vocal  ligaments. 
Crico-arytenoideus  posticus. — Dissection. — Open  the  pha- 
rynx by  a  vertical  incision   and   dissect  off  the  mucous 
membrane. 

FIG.  164.  This  muscle  will  then  be  seen  to 

arise  from  the  posterior  surface  of  the 
cricoid  cartilage,  and  to  pass  obliquely 
upward  and  outward,  as  a  flat  and 
strong  muscle,  to  be  inserted  into  the 
posterior  and  outer  part  of  the  base 
of  the  arytenoid  cartilage. 

Function. — To  antagonize  the  pre- 
ceding muscle  by  drawing  backward 
the  arytenoid  cartilages  and  making 
tense  the  vocal  chords. 

The    crico-arytenoideus    lateralis — 
(Fig.  163)  arises  from  the  side  of  the  cricoid  at  its  upper 

F,G.  163  represents  two  of  the  Muscles  of  the  Larynx,    a  Epiglottis.    6  Cri- 
coid cartilage,    c  Thyroid  cartilage,    d  Crico-arytenoideus  lateralis  mus 
t  Thyro-arytenoideus. 

FIG  164  represents  the  Muscles  on  the  posterior  Larynx,  a  Epiglottis.  6 
Thyroid  cartilage,  c  Cricoid  cartilage,  d  Crico-arytenoideus-posticus.  * 
Arytenoideus  transversus.  /  Arytenoideus  obliquus. 


MUSCLES  OF  THE  LARYNX.  531 

edge,  runs  obliquely  upward  and  backward,  and  is  in- 
serted into  the  base  of  the  arytenoid.  Function. — To  draw 
the  arytenoids  outward,  and  enlarge  the  rima  glottidis,  as 
in  inspiration.  This  is  a  dilator  muscle. 

Arytenoideus  obliquus  (Fig.  164J  arises  from  the  base  of 
one  arytenoid  cartilage,  and  is  inserted  into  the  apex  of 
the  other.  Its  fibres  are  small  and  sometimes  absent,  and 
it  is  described  by  some  anatomists  as  forming  a  part  of  the 
next  muscle. 

The  arytenoideus  transversus  (Fig.  164)  arises  from  the 
posterior  surface  of  the  one  arytenoid  cartilage,  and  runs 
transversely  to  be,  inserted  at  a  similar  point  on  the  other, 
and  filling  up  the  concavities  of  each.  This  is  a  single 
muscle. 

Function. — Both  these  latter  muscles  bring  the  aryte- 
noids together,  and  thus  close  the  glottis,  being  thereby 
constrictors  of  this  opening. 

The  tliyro-epiglottideus  has  indistinct  fibres,  which  arise 
from  the  inner  angle  of  the  thyroid  cartilage,  and  are 
inserted  into  the  base  and  side  of  the  epiglottis. 

Function. — To  draw  down  the  epiglottis. 

Aryteno-epiglottideus. — The  fibres  of  this  muscle  are  also 
indistinct.  It  arises  from  the  superior  extremities  of  the 
arytenoid  cartilages,  and  passes  forward  and  upward  to  be 
inserted  into  the  sides  of  the  epiglottis.  Function. — The 
same  as  the  latter  muscle. 

An  inferior  aryteno-epiglottidean  muscle  is  spoken  of  by 
Mr.  Hilton,  as  arising  from  the  arytenoid  cartilage  above 
the  vocal  chords,  and  thence  proceeding  forward,  over  the 
sacculus  laryngis,  to  be  inserted  into  the  side  of  the  epiglot- 
tis. Its  use,  he  thinks,  is  to  diminish  the  cavity  of  this 
sac,  and  compress  the  adjacent  mucous  glands. 

The  conjoint  action  of  all  these  muscles  tends  harmoni- 
ously to  one  common  end — the  production  of  voice ;  and 
although,  to  a  considerable  extent,  they  are  voluntary, 
nevertheless  the  will  has  not  perfect  command  over  their 
separate  actions;  and,  says  Mr.  Harrison,  "those  fibres 
which  are  connected  with  the  epiglottis,  and  which  proba- 


532         MUCOUS  MEMBRANE  OF  THE  LARYNX. 

bly  minister  to  the  function  of  deglutition,  rather  than  to 
that  of  voice,  appear  wholly  from  under  the  influence  of 
the  will,  and  act  in  that  spasmodic  or  convulsive  motion 
by  which  the  food  is  hurried  over  the  glottis,  and  precipi- 
tated into  the  oesophagus." 

MUCOUS   MEMBRANE  OF  THE  LARYNX  AND   GLANDS. 

The  mucous  membrane  of  the  larynx  is  a  continuation  of 
that  lining  the  mouth,  nose,  and  pharynx.  It  is  of  a  pink- 
ish color,  smooth  and  soft,  and  proceeds  from  the  base  of 
the  tongue  to  the  anterior  surface  of  the  epiglottis,  in  three 
folds,  the  middle  one  being  the  frcenum.  From  this  it 
passes  round  upon  the  posterior  surface  of  the  epiglottis, 
where  it  adheres  pretty  strongly ;  from  this  it  is  reflected 
backward  to  the  arytenoid  cartilages,  constituting  the  ary- 
teno-epiglottic  folds,  or,  according  to  some,  the  superior  or 
false  vocal  ligaments.  Here  it  becomes  continuous  with 
the  mucous  membrane  of  the  pharynx,  and  covers  the  pos- 
terior surface  of  the  larynx.  From  the  upper  ligaments  it 
descends  within  the  larynx,  to  the  inferior  or  true  chordae 
vocales,  lining  the  intervening  space,  called  the  ventricle 
of  Morgagni,  and  also  an  offset  from  this  ventricle,  termed 
the  sacculus  laryngis.  It  adheres  to  both  these  cavities 
loosely.  Upon  the  inferior  vocal  chords  it  is  very  thin  and 
adheres  strongly,  is  traced  downward,  lining  every  de- 
pression and  eminence,  and  is  continuous  with  that  found 
in  the  trachea,  bronchial  tubes,  and  air-cells  of  the  lungs. 

This  membrane  is  perforated  by  a  multitude  of  foramina, 
the  orifices  of  mucous  ducts.  Sixty  or  seventy  are  said  to 
belong  to  the  sacculus  laryngis.  Its  epithelium  is  found  to 
be  of  the  columnar  form  and  ciliated.  The  cilife  direct 
the  secretion  upward,  and,  according  to  Henle,  are  found 
extending  higher  up  in  front  than  upon  the  sides  or  be- 
hind. In  front  they  reach  to  the  posterior  surface  of  the 
epiglottis,  and  upon  the  sides  as  high  as  the  superior 
ligaments,  beyond  which  the  epithelium  takes  the  lami- 
nated form  of  the  pharynx  and  mouth.  The  upper  portion 
of  this  membrane  has  great  sensibility. 


KELATIONS  OF  THE  LARYNX.  533 

The  glands  of  the  larynx  are  distinguished  into  the  epi- 
glottic  and  arytenoid.  The  former  are  nothing  more  than 
a  mass  of  fatty  matter  situated  between  the  epiglottis  and 
thyro-hyoid  membrane.  The  only  epiglottic  glands,  says 
Cruveilhier,  belonging  to  the  epiglottis  are  found  within 
its  substance,  which  is  perforated  with  innumerable  orifices 
for  their  reception.  All  of  these  ducts  open  upon  the  laryn- 
geal  surface  and  furnish  a  considerable  quantity  of  mucus. 

The  arytenoid  glands  are  found  in  the  aryteno-epi glottic 
folds  of  mucous  membrane,  and  must  not  be  confounded 
with  some  little  cuneiform  cartilaginous  bodies  also  seen 
in  this  situation. 

Blood-vessels. — The  arteries  supplying  the  larynx  are 
four  in  number,  the  two  superior,  and  two  inferior  thyroid. 
The  former  come  from  the  external  carotid — the  latter 
from  the  subclavian.  The  veins  accompanying  the  arte- 
ries terminate  in  the  adjoining  venous  trunks. 

Nerves. — The  nerves  (Fig.  152)  supplying  the  larynx 
are  four  in  number,  and  all  come  from  the  pneumo-gastric 
or  par  vagum.  Two  are  above,  arise  near  the  base  of 
the  cranium,  and  are  called  the  superior  laryngeal.  The 
other  two  are  below,  arise  from  the  par  vagum  at  the  root 
of  the  neck,  and  are  called  the  inferior  laryngeal,  or  recur- 
rent nerves.  The  former  chiefly  supply  the  mucous  mem- 
brane of  the  larynx,  and  are  mostly  nerves  of  sensation. 
The  latter  go  principally  to  the  muscles,  and  are  mostly 
nerves  of  motion.  For  a  more  minute  description  of  the 
blood-vessels  and  nerves  of  the  larynx,  see  the  circulation 
and  nerves  of  the  neck. 

Relations  of  the  Larynx. — The  relations  of  the  human 
larynx  are  three-fold,  physical^  mental  and  organic.  The 
physical  are  those  which  the  larynx  has  with  atmospheric 
air  in  the  production  of  voice.  The  mental  are  those  con- 
nected with  the  cerebrum,  as  the  representative  and  instru- 
ment of  the  mind,  and  are  concerned  in  the  intellectual 
functions  of  language  and  oratory;  while  the  organic  refer 
more  particularly  to  the  relations  of  the  larynx  with  all 
the  other  organs  of  the  body.  By  means  of  the  pneumogas- 


534:  THE  TRACHEA. 

trie  nerve,  a  most  extensive  organic  connection,  as  already 
shown,  is  maintained  between  the  organ  of  voice  and  the 
functions  of  digestion,  respiration  and  circulation,  through 
the  agency  of  the  laryngeal,  pharyngeal,  cardiac,  pulmo- 
nary, cesophageal,  and  gastric  branches  of  this  pneumo- 
gastric  nerve,  associated  with  the  great  sympathetic  of  the 
neck,  chest,  and  abdomen.  But  the  most  important  rela- 
tion of  the  larynx  to  the  dentist  is  that  which  it  has  with 
the  mouth. 

Here  the  anatomical  and  physiological  relationship  is 
most  close  and  important.  The  same  mucous  membrane 
extends  from  the  one  cavity  into  the  other — from  the 
mouth  into  the  larynx.  Blood-vessels  and  nerves,  from 
the  same  sources  also  associate  the  two  sets  of  organs,  and 
lesion  or  destruction  of  the  one,  not  only  cripples  and  de- 
stroys its  own  functions,  but  also  extends  in  greater  or  less 
degree  to  those  of  the  other.  For  example,  the  loss  of 
teeth,  a  cleft  palate,  swollen  tonsils,  hare-lip,  &c.,  illus- 
trate the  injury  inflicted  upon  the  voice  as  well  as  the 
speech,  in  the  subversion  of  the  natural  relations  of  the 
mouth  and  larynx,  by  this  structural  change  in  the  organs 
belonging  to  the  mouth. 

The  same  result  would  follow  should  the  larynx  be 
altered  from  its  natural  condition  by  change  in  any  of  its 
parts. 

Trachea — (Vpa^ss  rough.) — The  trachea  (or  arteria  as- 
pera)  is  situated  upon  the  median  line  of  the  neck,  between 
the  larynx  above,  to  which  it  is  connected,  and  the  bron- 
chia below  into  which  it  divides.  It  commences  about  the 
fifth  cervical  vertebra  below  the  larynx,  and  descends  in 
front  of  the  oesophagus  and  vertebral  column,  into  the 
chest,  behind  the  arch  of  the  aorta,  and  in  front  of  the  third 
dorsal  vertebra,  where  it  terminates,  dividing  into  the  right 
and  left  bronchi,  which  go  to  the  lungs.  Its  length  and 
diameter  vary  according  to  age  and  sex,  but  the  average  in 
the  adult  is  about  five  inches  in  length,  and  from  three- 
quarters  to  one  inch  in  diameter. 

The  structure  of  the  trachea  consists  of  cartilage,  fibrous 


THE  TRACHEA. 


635 


and  elastic  tissue,   mucous  membrane  and  glands,   with 
muscular  ^fibres. 

The    cartilage,  FIG.  165. 

thin,  flexible,  read- 
ily compressed,  but 
very  elastic,  as- 
sumes the  form  of 
flattened  rings. — 
These  rings,  how- 
ever, are  not  com- 
plete, being  defi- 
cient in  their  poste- 
rior part,  and  form- 
ing only  about 
three-fourths  of  a 
circle.  They  resem- 
ble in  structure  that 
of  the  nose  and 
external  ear  more 
than  those  of  the  la- 
rynx. The  rings  run 
transversely,  being 
placed  one  above  the  other,  and  averaging  in  number  about 
eighteen.  Each  ring  is  convex  externally  and  concave 
internally,  enclosed  within  the  fibrous,  and  lined  by  the 
mucous  membrane.  These  cartilages  preserve  the  trachea 
as  a  permanently  open  tube  for  the  free  ingress  and  egress 
of  the  air.  Each  ring  is  about  two  lines  wide,  an  inch  and 
a  half  in  length,  and  a  line  in  depth ;  their  upper  and 
lower  edges  are  thin,  and  their  extremities  blunted.  Their 
size  is  irregular,  being  sometimes  larger  in  one  part  than 
another,  and  not  always  parallel.  The  lower  cartilages 
are  occasionally  bifid,  resembling  those  of  the  bronchi. 

The  fibrous  tissue  is  regarded  as  the  fundamental  part, 
forming   the   continued   tube   of  the   trachea,    being   at- 


FIG.    165  represents  the'Trachea  and  Bronchi.     1  Thyroid  cartilage.    2 
Cricoid  cartilage.    3  3  Trachea.     4  Left  bronchus.    5  Right  bronchus. 


536  THE  TRACHEA. 

tached  above  to  the  larynx,  and  continued  below  into  the 
bronchi.  It  has  the  cartilaginous  portion  deposited  in  it, 
and  forms  a  sheath  for  each  particular  ring,  and  supplying 
the  deficiency  behind,  where  the  rings  cease.  This  tissue 
is  regarded  as  belonging  to  the  yellow  elastic,  and  restores 
the  trachea,  when  elongated,  to  its  natural  length. 

The  elastic  tissue  presents  the  form  of  longitudinal  bands, 
is  found  between  the  mucous  and  muscular  coats,  at  the 
posterior  portion  of  the  trachea,  and  descends  into  the 
bronchi.  The  muscular  fibres  are  attached  to  the  ends  of 
the  cartilaginous  rings  behind — fill  up  their  deficiency, 
are  about  half  a  line  in  thickness,  and  run  transversely. 
They  are  exposed  by  dissecting  off  the  fibrous  coat,  when 
they  are  seen  to  be  thin  and  pale.  Their  function  is  to 
diminish  the  size  of  the  trachea,  and  assist  in  expelling 
the  mucus  during  expiration. 

The  mucous  membrane  extends  from  the  larynx,  lines  the 
trachea,  and  is  traced  downward  through  the  bronchial 
tubes  in  all  their  ramifications,  as  far  as  the  air-cells  of  the 
lungs.  This  membrane  is  thin,  delicate,  and  pale,  and 
presents  numerous  foramina,  the  orifices  of  mucous  glands. 
These  glands  are  found  most  abundantly  on  the  posterior 
surface  of  the  trachea,  situated  in  the  muscular  coat,  be- 
tween the  muscular  and  fibrous,  in  the  substance  of  th'e 
fibrous,  and  between  the  latter  and  the  mucous. 

They  mostly  present  the  form  of  small  ovoid  bodies,  but 
have  occasionally  attained  a  much  larger  size. 

The  blood-vessels  supplying  the  trachea  come  principally 
from  the  superior  and  inferior  thyroid  arteries.  The  veins 
are  superficial  and  deep,  and  enter  the  adjoining  veins. 
The  nerves  come  from  the  par  vagum. 


THE  ABDOMEN.  537 

CHAPTER  III. 

ACTIVE  ORGANS  OF  THE  TRUNK. 

SECOND     DIVISION. 
ORGANS  OF  THE  ABDOMEN. 

THE  active  organs  of  the  trunk  comprise,  in  the  physio- 
logical order,  most  of  the  organs  of  the  abdomen,  which  are 
divided  into  organs  of  digestion,  and  organs  of  absorption. 

GENERAL   OBSERVATIONS  UPON  THE  ABDOMEN. 

The  abdomen  (abdo,  to  hide)  is  situated  between  the 
chest  and  pelvis,  and  is  the  largest  cavity  in  the  body.  It 
is  bounded,  anteriorly  and  laterally,  by  the  abdominal 
muscles  and  fascia — posteriorly  by  the  quadrati  lumborum, 
psoa3  muscles,  crura  of  the  diaphragm,  and  lumbar  verte- 
brae— superiorly  by  the  diaphragm,  and  inferiorly  by  the 
pelvis. 

This  cavity  contains  a  variety  of  organs,  called  viscera, 
which,  for  the  purpose  of  localizing  them,  as  well  as  for 
the  convenience  of  description,  have  determined  anato- 
mists to  divide  the  abdomen  into  regions,  (Fig.  166.) 

By  drawing  two  transverse  lines  across  the  abdomen,  the 
one  superior  at  the  lower  margin  of  the  true  ribs,  the 
other  inferior  from  the  crista  of  the  ilium  on  the  one  side 
to  the  same  point  on  the  opposite — then  bisecting  these  at 
right  angles  by  two  vertical  lines,  one  upon  either  side,  and 
bringing  them  from  the  middle  of  Poupart's  ligament  to  the 
cartilage  of  the  eighth  rib,  then  taking  the  anterior  circum- 
ference of  the  abdomen,  we  have  marked  off  nine  regions. 

Three  of  these  occupy  the  middle  line,  and  three  are 
upon  either  side.  The  superior  median  region  is  called  the 
epigastric,  the  central,  the  umbilical,  the  inferior  middle,- 
the  hypogastric  region.  Those  upon  the  sides  are  the  right 
and  left  hypochondriac,  upon  eacli  side  of  the  epigastric; 
the  right  and  left  lumbar,  upon  each  side  of  the  umbilical ; 
and  the  right  and  left  iliac,  upon  each  side  of  the  hypo- 


538 


REGIONS   OF  THE  ABDOMEN. 


gastric  region.     Two   other   regions   are   spoken   of— the 
FlG>  166<  one   about  the  ensiform 

cartilage,  called  the  scro- 
liculus-cordis —  and  the 
other  about  the  symphy- 
sis  pubis,  called  the  re- 
gio  pubis.  These  several 
regions  are  more  or  less 
arbitrary,  and  the  dis- 
sector will  soon  find  that 
nature  does  not  confine 
herself  to  the  limits  here 
prescribed. 

The  epigastric  region 
(frtc,  over,  yasT'jfp,  stomach) 
contains  most  of  the  sto- 
mach, the  solar  plexus 
of  nerves,  the  pancreas, 
left  lobe  of  the  liver,  left 
extremity  of  the  right 
lobe,  and  is  traversed  in 

the  longitudinal  direction  by  the  aorta,  thoracic  duct,  and 

commencement  of  the  vena  azygos. 

The  umbilical  region  surrounds  the  navel,  and  contains  the 

upper  portions  of  the  small  intestines,  mesentery,  and  arch 

of  the  colon,  covered  by  the  omentum  majus. 

The  hypogastric  (vrto,  under,  ya^p,  stomach,)  contains  the 

lower  portion  of  the  small  intestines,  the  termination  of 

the  aorta,  and  commencement  of  the  vena-cava  ascendens. 
The  hypochondriac,  (Wo,  under,  xov8po$,  cartilage,)  right 

and  left,  are  on  either  side  of  the  epigastric  and  beneath 

FIG.  166  represents  the  Regions  of  the  Abdomen.  1  1  A  line  drawn  from 
the  crest  of  the  ilium  on  the  one  side,  to  the  same  point  on  the  opposite  side. 
5  2,  3  3  Lines  drawn  perpendicularly  from  the  anterior  inferior  spinous  pro- 
cesses, to  the  cartilages  of  the  ribs.  4  4  A  line  parallel  to  1  1  and  passing 
along  the  xiphoid,  and  most  prominent  costal  cartilages.  5  5  Right  and  left 
hypochondriac  regions.  6  Epigastric  region.  7  Umbilical  region.  8  8  Right 
and  left  lumbar  regions.  9  Hypogastric  region.  10  10  Right  and  left  iliac 
regions.  11  Pubic  region. 


WALLS  OF  THE  ABDOMEN.  539 

the  cartilages.  The  right  contains  the  right  lobe  of  the 
liver;  portion  of  the  duodenum,  and  colon.  The  left  con- 
tains the  spleen,  the  left  extremity  of  the  stomach,  part  of 
the  left  extremity  of  the  liver,  and  left  end  of  the  pancreas. 

The  lumbar  regions,  upon  each  side  of  the  umbilical,  con- 
tain the  right  and  left  kidneys,  with  the  ascending  and 
descending  portions  of  the  colon. 

The  iliac  are  on  each  side  of  the  hypogastric ;  the  right 
contains  the  termination  of  the  ilium,  and  commencement 
of  the  colon,  or  caput-coli — the  left  has  the  termination 
of  the  colon,  called  the  sigmoid  flexure.  The  lower  portions 
of  the  iliac  regions  receive  the  names  also  of  inguinal  or 
spermatic. 

^ 

SECTION   I. 

WALLS  OF  THE  ABDOMEN. 

The  anterior  and  lateral  walls  are  composed  chiefly  of 
muscles  and  fascia. 

Dissection. — Make  an  incision  from  the  symphysis  pubis, 
to  the  end  of  the  second  bone  of  the  sternum.  From  this 
latter  point,  carry  a  second  incision  obliquely  downward 
and  outward  towards  the  arm-pit,  and  onward  to  the  spine. 
A  third  incision,  commencing  on  the  second,  about  the 
middle  of  the  chest,  and  carried  downward  and  inward 
towards  the  spine  of  the  pubis,  will  be  in  the  direction  of 
the  fibres  of  the  superficial  or  external  oblique  muscle,  at  the 
upper  part  of  which  line  the  dissection  should  commence. 

The  muscles  are  five  pair — three  broad,  and  two  narrow. 
The  broad  are  the  external  oblique,  internal  oblique,  and 
transversalis ;  the  narrow  are  the  rectus  abdominis,  and 
pyramidalis. 

The  external  oblique  muscle,  (obliquus  externus  abdominis 
descendens)  so  named  from  the  direction  of  its  fibres,  is  the 
most  superficial  of  all  the  abdominal  muscles,  and  the 
largest.  It  is  thin  and  broad,  and  arises,  by  fleshy  and 
tendinous  digitations,  from  the  eight  or  nine  inferior  ribs, 
at  their  lower  edges  and  anterior  surfaces,  near  the  car- 


540 


MUSCLES   OF   THE   ABDOMEN". 


tilages.     The  five  superior  heads  interlock  with  the  ser- 
Fio.  167.  ratus    major 

anticus ;  the 
three  inferior 
with  the  latis- 
simus-dorsi, 
by  which  lat- 
ter it  is  a  lit- 
tle overlapped. 
The  fibres  of 
the  first  head 
blend  with, 
and  are  fre- 
quently  cov- 
ered by  a  slip 
from  the  pec- 
tor  alis  major. 
At  the  supe- 
rior part  this 
muscle  ap- 
pears thin 
and  aponeu- 
rotic,  and  so 

weak  as  to  be  not  unfrequently  removed,  without  great 
care  in  dissection.  It  descends  in  a  broad,  thin,  aponeuro- 
tic  tendon,  which  meets  its  fellow  the  whole  extent  of  the 
linea  alba,  and  the  two  together  cover  the  whole  front 
surface  of  the  abdomen.  The  posterior  and  lateral  portions 
are  muscular.  It  is  inserted  into  the  linea  alba,  where  it 
joins  its  fellow,  into  the  ensiform  cartilage,  tendinous  and 

FIG.  167  represents  the  superficial  Muscles  of  the  anterior  walls  of  the  Abdo- 
men. 1  Pectoralis  major.  2  Deltoid.  3  Latissimus  dorsi.  4  Serratus- 
major-anticus.  5  Subclavius.  6  Pectoralis  minor.  7  Coraco-brachialis.  8 
Biceps  flexor  cubiti.  9  Coracoid  process  of  scapula.  10  Serratus  major 
anticus,  after  removing  external  oblique.  11  External  intercostal  muscle. 
12  External  oblique.  13  Its  tendon.  14  Poupart's  ligament.  15  External 
abdominal  ring.  16  Rectus-abdominis.  17  Pyramidalis.  18  Internal  ob- 
lique. 19  Common  tendon  of  internal  oblique  and  transversalis.  20  Crural 
arch.  21  Fascia  lata.  22  Saphenous  opening. 


MUSCLES   OF  THE   ABDOMEN. 


541 


fleshy  into  the  anterior  half  of  the  crest  of  the  ilium  at  its 
outer  edge,  and  from  the  anterior  superior  spinous  process  of 
the  ilium  it  descends  in  the  form  of  a  cord  under  the  name 
ofPoupart's  ligament,  (which  ligament  is  regarded  simply  as 
a  folding  or  reflection  of  the  lower  margin  of  this  muscle,) 
to  the  spine  and  front  of  the  puhis,  and  thence  along  the 
pectineal  line  forming  Gimbernat's  ligament. 

When  the  two  external  oblique  muscles  are  neatly  exposed 
the  following  points  are  noticed,  the  linea-alba,  umbilicus^ 
FIG.  168.  lineae  semilunareSjlineas  transver- 

se, and  the  external  abdominal  or 
inguinal  ring.  The  linea  alba  ex- 
tends from  the  ensiform  cartilage, 
along  the  median  line  to  the  sym- 
physis  puhis.  It  is  formed  by  the 
common  union  of  the  tendons  of 
the  oblique  and  transverse  mus- 
cles of  opposite  sides,  which  pre- 
sent the  form  of  a  strong  ligament- 
ous  band,  whose  greatest  width 
and  thickness  is  at  the  umbilicus. 
The  umbilicus  is  situated  at  or  a 
little  below  the  centre  of  the  linea 
alba.  It  is  called  the  navel,  and 
in  the  fcetus  is  a  foramen  through 
which  pass  the  umbilical  vein,  arteries,  and  urachus. 
These  several  parts  in  the  adult  become  ligamentous  cords, 
being  no  longer  open  vessels,  which,  with  the  cellular  tis- 
sue that  surrounds  and  connects  them  together,  and  to  the 
tendinous  margin  of  the  foramen,  fill  up  this  opening.  The 
integument  mostly  containing  fat  in  the  adult,  presents  at 
the  umbilicus  a  depression.  Umbilical  hernia  occasionally 
occurs  at  this  place.  The  linece  semilunares  are  two  white 

FIG.  168  represents  right  Inguinal  Hernia,  a  Inferior  portion  of  aponeurotic 
tendon  of  external  oblique,  b  Poupart's  ligament,  c  Anterior  superior  spinous 
process,  d  Spine  of  pubis.  e  External  abdominal  ring.  /  Upper  column  of 
the  ring,  g  Lower  column  of  the  ring,  h  Semilunar  fibres  of  curved  shape, 
and  designed  to  strengthen  the  ring,  i  Iliac  portion  of  fascia  lata.  j  Pubic 
portion,  k  Saphenic  opening.  I  Falciform  edge. 


542  MUSCLES  OF  THE  ABDOMEN. 

ovally-curved  lines  upon  each  side,  and  about  three  Inches 
distant  from  the  linea  alba,  formed  by  the  splitting  of  the 
tendon  of  the  internal  oblique,  where  it  proceeds  to  form  a 
sheath  for  the  rectus  muscle.  The  linece  transversce  are  three 
or  four  short  lines,  going  from  the  linea  alba  transversely 
across  the  rectus  muscle,  to  the  lineae  semilunares ;  one  of 
these  lines  is  seen  at  the  umbilicus,  another  at  the  lower 
end  of  the  ensiform  cartilage,  a  third  between  these  two 
points,  and  sometimes  a  fourth  midway  the  navel  and  pubis. 

The  external  abdominal  ring  (Fig.  168)  is  situated  in  the 
lower  part  of  the  tendon  of  the  external  oblique,  superior 
and  external  to  the  spine  of  the  pubis  upon  each  side,  above 
Poupart's  ligament.  This  ring  (improperly  so  called)-  is 
triangular  in  form,  having  its  base  toward  the  pubis,  and 
its  apex  external  and  superior.  The  sides  of  this  opening 
are  termed  columns  or  pillars,  superior  and  inferior.  The 
superior  column  is  broad,  and  its  fibres  go  to  the  sym- 
physis  pubis,  and  decussate  with  those  of  its  fellow  in  front 
of  the  pubis  and  dorsum  of  the  penis.  The  inferior 
column,  called  also  the  pubic  end  of  Poupart's  ligament,  or 
third  insertion  of  the  external  oblique,  goes  to  the  spine  of 
the  pubis  and  about  an  inch  along  its  crest. 

This  ring  varies  as  to  size ;  it  is  larger  in  the  male  than 
the  female,  its  average  dimensions  being  from  an  inch,  to 
an  inch  and  a  half  in  the  longest  direction,  and  about  half 
an  inch  transversely.  This  opening  is  very  interesting 
from  the  fact  of  its  transmitting  in  the  male  the  spermatic 
cord  and  cremaster  muscle,  and  in  the  female  the  round 
ligament  of  the  uterus,  and  particularly  so  to  the  surgeon, 
from  being  the  seat  of  that  form  of  hernia  called  oblique 
inguinal. 

Function. — Tlte  external  oblique  assists  in  expiration  by 
compressing  the  abdominal  viscera,  which  press  up  the 
diaphragm,  and  thus  diminish  the  thoracic  cavity.  It  also 
aids  in  evacuating  the  foeces  and  urine,  and  brings  the 
thorax  and  pelvis  toward  each  other. 

Internal  oblique — obliquus  internus  abdominis  ascendens. 
(Fig.  167.)  Dissection. — Kemove  the  external  oblique  by  an 


MUSCLES  OF  THE  ABDOMEN.  543 

incision  along  the  ribs,  just  below  its  origin;  a  second  incis- 
ion is  to  be  made  from  the  anterior  superior  spinous  pro- 
cess transversely  through  the  aponeurotic  tendon  of  the 
external  oblique,  to  the  linea  alba,  extending  the  incision 
along  the  crest  of  the  ilium.  The  external  ring  and  pillars 
will  thus  be  left  entire  for  subsequent  examination.  Dis- 
sect from  behind  forward  and  in  the  course  of  the  fibres  of 
the  muscle. 

This  muscle  takes  one  of  its  names  from  the  most  of  its 
muscular  fibres  pursuing  an  upward  direction.  It  arises 
tendinous  from  the  fascia  lumborum,  tendinous  and  fleshy 
from  the  whole  of  the  crest  of  the  ilium,  and  fleshy  from  the 
upper  half  of  Poupart's  ligament.  The  fibres  of  this  muscle 
do  not  all  ascend,  those  at  the  lower  part  pursue  rather  a 
transverse  and  downward  direction.  The  fleshy  portion  is 
continued  farther  forward  than  the  external  oblique,  and 
ends  in  a  flat  tendon,  which  at  the  outer  edge  of  the  rectus 
divides  into  two  layers,  one  of  which  unites  with  the  tendon 
of  the  external  oblique  to  go  in  front  of  the  rectus,  the  other 
joins  the  tendon  of  the  transversalis  and  passes  behind  the 
rectus,  thus  forming  a  complete  sheath  for  this  muscle. 
About  half  way  between  the  umbilicus  and  pubis,  the 
whole  of  these  tendons  pass  in  front  of  the  rectus,  leaving 
this  muscle  to  rest  upon  the  peritoneum.  The  internal 
oblique  is  inserted  tendinous  into  the  ensiform  cartilage, 
and  the  whole  length  of  the  linea  alba,  tendinous  into  the 
cartilages  of  the  seventh  and  eighth  ribs,  and  fleshy  into 
the  cartilages  of  the  four  inferior  ribs,  function. — The 
same  as  external  oblique. 

Transversalis  abdominis. — Dissection. — Remove  the  inter- 
nal oblique  by  incisions  from  the  ribs  above,  and  crest  of 
the  ilium  and  Poupart's  ligament  below.  The  dissection 
should  begin  near  the  crest  of  the  ilium,  as  here  will  be 
seen  an  artery,  the  circumflexa  ilii,  and  some  cellular  tissue, 
showing  distinctly  the  line  of  separation  between  the  two 
muscles.  The  fibres  of  this  muscle  run  transversely.  It 
arises  tendinous  from  the  fascia  lumborum,  from  the  inner 
margin  of  the  whole  crest  of  the  ilium,  fleshy  anteriorly 


544 


MUSCLES   OF  THE  ABDOMEN. 


and  tendinous  posteriorly,  from  the  external  half  or  third 
FIG.  169.  j  of  Poupart's  ligament,  and  ten- 

dinous and  fleshy  from  the  in- 
ner surfaces  of  the  cartilages 
of  the  six  or  seven  lower  ribs. 
These  fibres  all  end  in  a  tendon, 
which  near  the  linea  semilunaris, 
unites  with  the  posterior  layer 
of  the  internal  oblique,  and  is 
inserted  into  the  ensiform  car  til- 
age,  the  whole  length  of  the  linea 
alba,  the  upper  margin  of  the 
pubis,  and  the  linea  innominata- 
This  tendon  passes  behind  the 
rectus,  except  about  midway  be- 
tween the  pubis  and  umbilicus, 
where  the  whole  pass  in  front. 
The  union  of  this  tendon  with 
that  of  the  internal  oblique  at 
the  crista  of  the  pubis,  receives 
the  name  of  the  conjoined  tendon  which  forms  the  floor  of 
the  external  ring.  Function.— -To  compress  the  viscera  and 
aid  in  expiration. 

The  rectus  abdominis  (Fig.  167)  is  exposed  by  a  longitu- 
dinal incision  through  the  tendons  of  the  broad  muscles, 
extending  from  the  ensiform  cartilage  to  the  pubis,  and 
turning  these  tendons  over  to  the  linea  semilunaris,  when 
both  the  recti  muscles  will  be  seen  lying  side  by  side,  along 
the  median  line.  They  are  long  and  straight,  thicker  be- 
low than  above,  and  arise  by  a  flat  tendon  from  the  supe- 
rior margin  of  the  pubis  between  the  symphysis  and  spine ; 
the  fibres  ascend  and  are  inserted  into  the  ensiform  carti- 
lage, and  cartilages  of  the  fifth,  sixth,  and  seventh  ribs. 
The  recti  are  about  three  inches  in  breadth,  and  present, 

FIG.  169  represents  the  Transversalis  Muscle,  a  Latissimus  dorsi.  6  Ser- 
ratus  major  anticus.  c  External  oblique,  d  External  intercostals.  e  Inter- 
nal intercostals.  /  Transversalis  abdominis.  g  Fascia  lumborum.  h  Sheath 
of  the  rectus,  its  posterior  part,  i  Rectus  abdominis  cut  off,  and  its  sheath. 
j  Rectus  abdominis  of  right  side,  k  Crural  arch.  I  Gluteus  maximus. 


FASCIA  OF  THE  ABDOMEN.  545 

three  or  four  irregular  transverse  lines,  which  are  tendin- 
ous intersections  of  these  muscles,  and  called  linece  trans- 
verses  Their  situations  correspond  to  the  umbilicus,  the 
ensiform  cartilage,  midway  these  two  latter  points,  and 
sometimes  helow  the  navel.  These  lines  adhere  strongly 
to  the  tendons,  and  linea  alba  in  front,  and  are  not 
often  seen  on  the  back  of  these  muscles.  Function. — To 
bring  the  chest  and  pelvis  toward  each  other  and  compress 
the  bowels. 

The  pyramidalis ,  (Fig.  167,)  situated  at  the  lower  part  of 
the  abdomen,  is  a  short  muscle  and  arises  by  a  broad,  fleshy, 
and  tendinous  base,  from  the  superior  border  of  the  sym- 
physis,  extending  to  the  spine  of  the  pubis,  having  the  rec- 
tus  behind,  and  the  external  oblique  in  front.  Its  fibres 
ascend  in  a  tapering  manner,  and  are  inserted  into  the  linea 
alba,  halfway  between  the  pubis  and  umbilicus.  This  mus- 
cle is  placed- in  a  sheath  between  the  tendons  of  the  broad 
muscles,  and  is  not  unfrequently  absent.  Function. — To  as- 
sist the  rectus,  and  make  tense  the  linea  alba. 

The  conjoint  action  of  all  these  muscles  is  to  lessen  the 
cavity  of  the  abdomen  and  compress  the  viscera,  and,  al- 
though they  are  voluntary  muscles,  and  also  aid  in  expi- 
ration, defecation,  vomiting,  and  parturition,  they  do  some- 
times act  without  the  consciousness  of  the  individual,  and 
are  referred  to  by  Mr.  Harrison  as  strong  examples  of  the 
influence  of  the  excito-motory  nerves,  in  consequence  of 
their  sympathy  with  the  lungs,  larynx,  stomach,  bladder, 
and  uterus,  sympathies  which  cannot  be  traced  to  any 
direct  nervous  connection. 

Fasciae  of  the  Anterior  and  Lateral  Walls. — The  fascia 
superficialis  and  the  fascia  transversalis. 

The  superficial  fascia  is  sub-cutaneous,  and  continuous 
with  that  covering  the  chest.  It  consists  of  condensed  cel- 
lular structure,  and  is  variable  in  consistency  in  different 
parts — being  weak,  and  cellular  in  some,  and  aponeurotic 
in  others.  It  is  traced  over  the  abdominal  muscles  below, 
to  Poupart's  ligament,  to  which  it  slightly  adheres — and 
thence  upon  the  thigh  for  a  short  distance — also  upon  the 
35 


546  FASCIA  OF  THE  ABDOMEN. 

dorsum  of  the  penis,  forming  a  suspensory  ligament.  It 
gives  covering  to  the  spermatic  cord,  which  descends  into 
the  scrotum,  and  is  continuous  with  the  fascia  of  the  per- 
ineum. This  fascia,  called  also  Camper's  fascia,  is  thin 
and  weak  above,  and  strong  and  dense  below,  where  it 
envelops  the  glands  and  a  quantity  of  adipose  matter, 
and  has  hence  received  the  additional  name  of  adipo-gland- 
ular  structure.  About  an  inch  below  Poupart's  ligament 
it  becomes  closely  connected  with  the  fascia  lata,  in  conse- 
quence of  which  adhesion,  femoral  hernia  is  disposed  to" 
take  the  upward  direction.  In  some  of  the  lower  animals 
this  fascia  is  well  developed — presents  a  yellowish  aspect, 
and  is  very  strong  and  elastic,  by  which  arrangement  it 
is  well  adapted  to  protect  and  support  the  abdominal 
viscera. 

The  fascia  transversalis  is  situated  beneath  the  trans- 
verse muscle,  and  rests  upon  the  peritoneum.  It  is  of  va- 
rying strength  and  consistency  at  different  points,  being 
cellular  in  some,  and  decidedly  aponeurotic  in  others.  It 
is  generally  a  thin  tendinous  membrane,  distinctly  fibrous 
and  strong  in  each  inguinal  region,  and  closely  adhering 
to  the  transverse  muscle.  It  is  attached  to  the  inner  mar- 
gin of  Poupart's  ligament  its  whole  length,  to  the-crista 
of  the  pubes  behind  the  common  tendon  of  the  internal 
oblique  and  transverse  muscles,  to  the  external  margin  of 
the  rectus,  thence  lining  the  transverse  muscle,  and  the 
whole  of  the  abdomen  as  high  as  the  thorax. 

The  lower  portion  of  this  fascia  is  extremely  interesting 
from  its  connection  with  inguinal  hernia.  As  already 
stated,  it  is  here  very  strong  and  aponeurotic,  and  closely 
attached  to  the  whole  of  Poupart's  ligament.  Dissection, 
however,  shows  that  it  does  not  stop  at  this  ligament,  but 
that  a  portion  can  be  traced  beneath  the  crural  arch,  in 
front  of  the  femoral  vessels,  called  their  anterior  sheath; 
and  backward,  as  continuous  with  the  fascia  iliaca,  a  strong 
membrane  covering  the  iliacus  and  psoas  muscles.  Where 
these  two  fasciae  meet  and  are  united  to  Poupart's  liga- 
ment, there  is  seen  a  white,  dense  line,  extending,  in  some- 


FASCLE  OP  THE  ABDOMEN.  54f 

what  of  a  curve,  from  the  femoral  artery  to  the  crest  of 
the  ilium,  enclosing  the  internal  FIG.  170. 

circumflex  artery  and  veins.  At 
this  common  point  of  union  be- 
tween these  three  several  struc- 
tures, protrusion  of  any  of  the 
viscera  beneath  the  crural  arch, 
from  the  femoral  artery  outward, 
is  effectually  guarded  against 
both  by  the  great  strength  of  this 
union,  and  the  firm  support  it 
gives  to  all  the  organs  pressing 
upon  this  point. 

From  an  inch  and  a  half  to 
two  inches  from  the  spine  of  the 
pubis,  and  about  a  half  or  three- 
quarters  of  an  inch  above  Poupart's  ligament,  there  is  an 
opening  in  this  fascia,  called  the  internal  abdominal  ring. 
It  is  found  about  midway  between  the  symphysis  of  the  pubis 
and  spine  of  the  ilium.  Through  this  opening  the  spermatic 
cord,  or  round  ligament,  passes  out  of  the  abdomen.  The 
opening  is  not  distinct,  as  the  cord,  in  passing  through  the 
fascia  transversalis,  pushes  before  it  a  reflection  from  this 
fascia,  which,  from  its  shape,  is  called  the  infwidibuliform, 
or  fascia  propria.  From  this  internal  ring  or  opening,,  to 
the  external  ring  in  the  tendon  of  the  external  oblique 
muscle,  there  is  a  canal  called  the  oblique  inguinal  canal — a 
distance  of  about  eighteen  lines,  along  which  the  oblique 
inguinal  hernia  descends. 

This  canal  is  bounded,  in  front,  by  the  common  integu- 
ments, superficial  fascia,  and  tendon  of  the  external  ob- 
lique— behind,  by  the  fascia  transversalis,  the  conjoined 
tendons,  and  triangular  ligament — below,  by  Poupart's 

FIG.  170  represents  the  Transversalis  Fascia,  and  internal  ring,  a  Internal 
oblique.  6  Part  of  transversalis.  c  Arched  border  of  these  two  muscles  form- 
ing the  upper  boundary  of  the  inguinal  canal,  d  Poupart's  ligament,  t  Fascia 
transversalis.  /Conjoined  tendon  of  internal  oblique  and  transversalis;  letters 
«  /  form  the  posterior  boundary  of  the  canal,  g  Internal  abdominal  ring,  k 
External  ring,  the  dotted  lines  show  the  course  of  the  cord. 


548 


BLOOD-VESSELS   OF   THE   ABDOMEX. 


and  Gimbernaut's  ligaments — and  above,  by  the  fleshy  mar- 
gin of  the  transverse  muscle. 


BLOOD-VESSELS    OF   THE   ANTERIOR   AND   LATERAL   WALLS. 

The  arteries  are  external  and  internal.  The  former  arise 
from  the  femoral  artery,  ascend  over  Poupart's  ligament, 

and  consist  of  the  ex- 
ternal or  superficial 
circumflexa  ilii,  ex- 
ternal epigastric,  and 
external  pudic,  pro- 
ceeding between  the 
skin  and  superficial 
fascia,  to  be  distrib- 
uted about  the  spinous 
process  of  the  ilium, 
the  umbilicus,  and  pu- 
bis.  The  internal  or 
deep  arteries  have  the 
same  name,  the  prin- 
cipal of  which  are  the 
circumflexa  ilii  proper, 
and  internal  epigastric, 
both  of  which  come 
from  the  external  iliac 
just  as  the  latter  is  passing  under  Poupart's  ligament. 
The  latter  ascends  on  the  pubic  side  of  the  internal  ring, 
between  the  fascia  transversalis  and  peritoneum,  to  the 
rectus  muscle,  upon  which  it  ramifies  and  ascends  to  anas- 
tomose with  the  internal  mammary,  which  descends  from 

FIG.  171  represents  an  internal  view  of  the  Anterior  Abdominal  Wall, 
with  its  Blood-vessels.  1  1  Linea  alba.  2  2  Linea  semilunaris.  3  3  Lineoe 
transversae.  4  Lower  border  of  sheath  of  rectus.  5  6  Rectus  abdominis. 
7  Internal  mammary  artery.  8  Musculo-phrenic  branch.  9  9  Diaphragm. 
11  Section  of  the  three  abdominal  muscles.  12  Section  of  external  and  inter- 
nal oblique.  13  External  iliac  artery.  14  Circumflexa  ilii  artery.  15  Ex- 
ternal iliac  vein.  16  Crural  ring.  17  Gimbernat's  ligament.  19  20  Arch 
formed  by  the  lower  border  of  internal  oblique,  and  transversalis  muscle.  22 
Conjoined  tendon  of  internal  oblique  and  transversalis. 


MUSCLES  OP  THE  ABDOMEN. 


549 


the  subclavian  to  supply  the  anterior  abdominal  walls. 
Each  artery  has  one  or  two  accompanying  veins  which 
open  into  the  femoral,  saphena,  iliac,  and  subclavian  veins- 

The  nerves  come  principally  from  the  lumbar  plexus. 

The  posterior  walls  of  the  abdomen  include  muscles,  fas- 
cia, blood-vessels,  nerves,  and  lumbar  vertebrse. 

The  muscles  are  quadratus  lumborum,  psoas  magnus, 
psoas  parvus,  iliacus  internus. 

The  quadratus  lumborum,  situated  between  the  last  rib 
and  the  ilium,  and  composing  a  great  part  of  the  poste- 
rior abdominal  wall,  is  FIG.  172. 
enclosed  in  a  strong 
sheath,  formed  of  the 
middle  and  anterior 
layers  of  the  tendon  of 
the  transverse  muscle. 
By  removing  the  ante- 
rior layer  of  this  sheath 
with  the  colon  and  kid- 
ney, the  muscle  is  ex- 
posed. It  presents  an 
oblong  form,  and  arises 
tendinous  and  fleshy 
from  the  posterior  crest 
of  the  ilium  and  ilio 
lumbar  ligament,  and 
ascends  to  be  inserted 
into  the  transverse  pro- 
cesses of  the  last  dorsal 
and  four  upper  lumbar 
vertebrae  by  tendinous 
slips,  and  into  the  ver- 
tebral half  of  the  last 
rib.  Function. — To  aid  in  expiration,  by  drawing  down 
the  last  rib,  and  flexing  the  spine  to  one  side. 

FIG.  172  represents  Muscles  of  the  posterior  wall  of  Abdomen,  a  Quadratus 
lumborum.  6  Iliacus  internus.  c  Psoas-magnus.  d  Psoas  parvus.  t  Obtu- 
rator externus. 


550  MUSCLES  OF  THE  ABDOMEN-. 

The  psoas  magnus — t-oa,  the  loins,  (Fig.  172,)  is  round, 
long,  thick,  fleshy  above,  and  arises  by  two  planes,  the 
first  fleshy  from  the  sides  of  the  bodies  of  the  lumbar  and 
last  one  or  two  dorsal  vertebrae,  the  second  from  the  trans- 
verse processes  of  all  the  lumbar  vertebrae ;  the  two  sets 
unite  to  form  an  oblong  muscle,  which  descends  along  the 
lateral  margin  of  the  brim  of  the  pelvis,  beneath  Poupart's 
ligament,  and  about  its  centre,  and  is  inserted  by  a  tendon 
common  to  it  and  the  iliacus  internus,  into  the  trochanter 
minor,  and  fleshy  for  about  an  inch  below  into  the  linea 
aspera.  A  bursa  is  found  between  this  tendon  and  the 
trochanter,  and  also  between  it  and  the  pubis  as  it  passes 
over.  Function. — To  flex  the  thigh  on  the  pelvis,  or  the 
body  on  the  thigh.  It  can  also  rotate  the  thigh  outward. 

The  psoas  parvus  (Fig.  1*72)  has  a  short  belly  and  along 
tendon.  It  arises  fleshy  from  the  sides  of  the  bodies  of 
the  last  dorsal  and  first  lumbar  vertebrae,  and  from  the 
intervertebral  ligament.  Its  tendon  begins  about  the  fourth 
lumbar  vertebra,  and  passes  down  to  be  inserted  into  the 
linea  innominata,  and  by  a  broad  aponeurotic  expansion  into 
the  fascia  iliaca.  This  muscle  is  situated  at  the  anterior  and 
internal  edge  of  the  psoas  magnus,  and  is  often  wanting. 
Function. — To  flex  the  body  or  raise  the  pelvis,  and  draw 
up  the  sheath  of  the  femoral  vessels,  which,  it  is  thought, 
in  sudden  flexion  will  lessen  the  liability  to  injury  of  these 
vessels. 

The  iliacus  internus  (Fig.  172)  is  situated  on  the  outside  of 
the  psoas  magnus,  and  fills  up  the  venter  of  the  ilium.  It 
arises  fleshy  from  the  last  lumbar  vertebra  by  its  transverse 
process,  from  the  ilio-lumbar  ligament,  inner  margin  of  the 
crista  ilii,  venter  of  the  ilium,  and  intervening  notch  be- 
tween the  two  anterior  spinous  processes  of  the  ilium — also 
from  the  capsule  of  the  hip  joint.  It  unites  with  the  tendon 
of  the  psoas  magnus,  and  is  inserted  along  with  it  into  the 
trochanter  minor.  A  large  bursa  is  found  between  this 
common  tendon  and  the  capsule  of  the  hip  joint,  which 
occasionally  communicates  with  the  cavity  of  the  joint. 

Function. — The  same  as  the  psoas  magnus. 


FASCIA  OF  THE  ABDOMEN.  551 


FASCIA   OF  THE  POSTERIOR  WALL. 

Fascia  iliaca. — This  fascia,  called  also  lumbo-iliac  apon- 
eurosis,  occupies  the  iliac  region,  and  may  be  traced  as  a 
strong  membrane  covering  the  iliacus  and  psoas  muscles, 
connected  with  Poupart's  ligament  from  the  anterior  supe- 
rior process  of  the  ilium  as  far  as  the  external  iliac  artery, 
where  it  passes  beneath  this  vessel  upon  the  thigh,  form- 
ing the  posterior  sheath  of  the  femoral  vessels,  and  being 
continuous  with  the  pectineal  portion  of  the  fascia  lata. 
Along  Poupart's  ligament  it  is  also  connected  with,  and 
continued  into  the  fascia  transversalis.  The  fascia  iliaca 
can  be  followed  below  into  the  pelvic  fascia ;  above,  after 
covering  the  psoas  and  iliacus  muscles,  as  high  as  the 
diaphragm,  it  is  connected  to  the  ligamentum  arcua- 
tum  and  sides  of  the  lumbar  vertebrse,  where  it  forms  a 
series  of  arches  for  the  passage  of  the  lumbar  vessels  and 
some  of  the  nerves. 

This  fascia  has  the  double  use  of  giving  strength  to  the 
lower  part  of  the  abdomen  by  its  firm  union  with  Pou- 
part's ligament,  and  of  furnishing  a  strong  covering  to 
the  psoas  and  iliacus  muscles.  With  the  fascia  transver- 
salis,  it  also  forms  a, sheath  for  the  femoral  vessels  at  the 
upper  part  of  the  thigh.  At  this  point  these  two  fascias 
are  still  further  connected  by  two  vertical  partitions,  one 
of  which  is  between  the  femoral  artery  and  vein,  the  other 
between  the  vein  and  the  femoral  or  crural  ring. 

Superior  wall  of  the  abdomen,  (the  diaphragm.) — Dissec- 
tion.— To  expose  this  muscle,  the  abdominal  viscera  should 
be  removed,  and  the  loins  raised  by  placing  a  billet  of  wood 
beneath  the  lumbar  vertebra?.  Then,  dissecting  off  the 
peritoneum  from  the  lower  surface,  the  diaphragm  will  be 
seen  as  a  movable  curtain,  dividing  and  separating  the 
abdominal  and  thoracic  cavities.  This  muscle  is  broad, 
and  somewhat  circular  in  its  shape,  consisting  of  a  fleshy 
and  tendinous  portion,  and  presenting  two  surfaces — a 
superior  arid  inferior,  or  thoracic  and  abdominal,  the  upper 
surface  being  convex,  the  lower  concave.  The  diaphragm 


552 


THE  DIAPHRAGM. 


FIG.  173. 


is  generally  divided  into  two  portions,  called  the  greater 
and  lesser  diaphragm. 

The  greater  arises 
fleshy  from  the  pos- 
terior part  of  the 
ensiform  cartilage, 
from  the  inner  sur- 
face of  the  cartilages 
of  the  seventh  true, 
and  all  the  false  rihs, 
and  for  some  extent 
fiom  the  osseous  por- 
tion of  the  last  two 
rihs.  This  origin,  in- 
cluding almost  a  cir- 
cle, indigitates  with 
the  transversalis 
muscle.  Between  the  ensiform  cartilage  and  the  ribs  there 
is  a  triangular  space  containing  cellular  and  fatty  matter, 
and  giving  passage  to  the  internal  mammary  vessels,  in 
which  there  is  occasionally  found  an  opening  through 
which  some  of  the  abdominal  viscera  pass  into  the  chest, 
constituting  hernia.  From  the  circumference  of  this 
greater  muscle  of  the  diaphragm,  the  fibres  radiate  or  con- 
verge to  a  central  tendon  called  the  cordiform  tendon.  This 
tendon,  which  has  been  compared  to  the  heart  of  a  playing 
card,  is  a  tendiiious  expansion  of  considerable  extent,  and 
of  silvery  whiteness,  having  its  notch  toward  the  spine  and 
its  apex  to  the  sternum.  All  round  its  circumference  the 
muscular  portion  of  the  diaphragm  is  attached  to  it.  The 
lesser  diaphragm  consists  of  two  crura,  right  and  left,  which 
are  situated  upon  each  side  of  the  lumbar  vertebrae.  The 

FIG.  173  represents  the  Diaphragm  or  superior  wall  of  the  Abdomen.  1  2 
3  Greater  muscle  of  the  diaphragm.  4  Space  where  hernia  sometimes  occurs. 
5  Ligamentum  arcuatum.  6  Origin  of  psoas-magnus.  7  Opening  for  lesser 
splanchnic  nerve.  8  One  of  the  crura  of  the  diaphragm.  9  Fourth  lumbar 
yertebra.  10  Another  of  the  crura  of  the  diaphragm.  11  Opening  for  the 
aorta.  12  Opening  for  the  oesophagus.  13  Opening  for  the  ascending  cava* 
14  Psoas  magnus.  15  Quadratus  lumborum. 


THE  DIAPHRAGM.  553 

right  cms  is  the  larger  of  the  two  and  arises  tendinous  from 
the  sides  and  anterior  surface  of  the  four  upper  lumbar  ver- 
tebraB  and  their  intervertebral  ligaments;  the  left  crus,  being 
the  smaller,  comes  from  the  two  upper  vertebra}.  Both  crura 
ascend  and  are  connected  upon  the  last  dorsal  vertebra  by 
a  tendinous  cord,  semilunar  in  shape,  which  arches  over  the 
aorta  and  thoracic  duct.  A  little  above  this  point  the  crura 
approach  each  other  and  decussate,  and  pass  on  to  be  in- 
serted into  the  notch  and  posterior  margin  of  the  central 
cordiform  tendon.  The  greater  and  lesser  muscles  of  the 
diaphragm  have  their  attachments  completed  by  the  liga- 
mentum  arcuatum,  which  extends  from  the  transverse  pro- 
cess of  the  first  lumbar  vertebra,  and  body  of  the  second,  to 
the  twelfth  rib.  To  the  upper  margin  of  this  tendon  the 
diaphragm  is  attached,  and  to  its  lower  margin  the  psoas 
magnus  muscle,  and  under  it  is  placed  the  sympathetic 
nerve.  The  diaphragm  contains  three  large  openings ;  one, 
for  the  aorta,  thoracic  duct,  and  great  splanchnic  nerves,  is 
a  long  elliptical  foramen,  situated  between  and  behind  the 
crura,  and  in  front  of  the  bodies  of  the  last  dorsal  and  three 
upper  lumbar  vertebra?.  The  second  opening  is  about  three 
inches  above  and  to  the  left  of  the  aortic.  Its  form  is  that 
of  a  long  oval,  situated  in  the  posterior  part  of  the  muscle, 
between  the  spine  and  notch  of  the  tendon,  the  decussa- 
ting fasciculi  forming  its  parietes  and  separating  it  from 
the  aortic.  The  oesophagus  and  eighth  pair  of  nerves  pass 
through  this  foramen.  The  third  opening  is  for  the  vena 
cava  ascendens.  It  is  a  large  foramen  a  little  higher  than 
the  oesophageal,  situated  to  the  right  and  in  the  back  part 
of  the  cordiform  tendon.  It  is  something  of  a  quadrilateral 
figure,  having  its  margins  tendinous  all  round,  with  fasci- 
culi passing  upon  the  vein  above  and  below,  and  thus  afford- 
ing an  arrangement  by  which  it  is  kept  constantly  open, 
and  all  interruption  to  the  circulation  prevented. 

The  blood-vessels  of  the  diaphragm  are  the  phrenic,  the 
first  branches  of  the  aorta  after  entering  the  abdomen,  the 
internal  mammary,  intercostals,  and  branches  from  the  re- 
nal and  lumbar  arteries.  The  veins  open  either  into  the 


ORGANS  OF  DIGESTION. 

cava  or  contiguous  veins  which  pass  into  the  same  trunk. 
The  nerves  are  numerous,  supplying  the  diaphragm,  and 
come  from  the  phrenic,  pneumogastric,  spinal,  and  sym- 
pathetic. 

Function. — This  muscle  is  an  important  agent  in  respira- 
tion. By  its  contraction  its  convex  surface  descends,  and 
thus  the  diameters  and  cavity  of  the  chest  are  enlarged  and 
more  air  allowed  to  enter  the  lungs  in  respiration.  By  its 
contraction  it  also  acts  in  concert  with  the  abdominal  mus- 
cles in  vomiting,  expelling  the  fasces,  and  in  parturition. 
By  its  relaxation  the  diaphragm  ascends  into  the  cavity  of 
the  chest,  diminishes  this  cavity  and  thus  aids  in  expira- 
tion. The  inferior  wall  will  be  examined  in  another  place. 

SECTION    II. 
ORGANS  OF  ABDOMINAL  DIGESTION. 

These  comprise,  1.  The  organ  of  cliymification,  consist- 
ing of  the  stomach;  2.  The  organs  of  cliylification,  com- 
posed of  the  small  intestine  and  the  large  intestine,  which 
however  more  properly  belongs  to  the  function  oifcecation  ; 
B.  Assistant  organs  of  digestion,  composed  of  the  liver, 
the  pancreas,  and  the  spleen. 

Before  giving  the  description  of  the  abdominal  viscera 
separately,  it  is  necessary  first  to  premise  a  few  general  ob- 
servations upon  the  peritoneum,  a  membrane  which  is  com- 
mon to  each  and  the  whole,  and  which  forms  the  lining 
membrane  of  the  abdominal  walls. 

Peritoneum,  (xtpitMtiv,  to  extend  around.) — The  perito- 
neum is  a  serous  membrane,  and  the  largest  one  in  the 
body.  Like  all  serous  membranes,  it  is  a  shut  sac.  This  is 
true  of  the  male  peritoneum,  but  in  the  female  there  is  an 
opening  at  the  extremities  of  the  Fallopian  tubes,  which 
Mr.  Harrison  observes  is  more  apparent  than  real,  for  he 
thinks  it  probable  that  these  fimbrias  are  closed  at  all  times 
except  when  in  contact  with  or  adhering  to  the  ovaries. 
Thus,  in  ascites,  the  water  is  never  found  escaping  by 
these  openings,  nor  air,  nor  fluid,  when  injected  in  the  dead 


PERITONEUM. 


555 


body;  and  if  such  be  the  facts,  the  female  peritoneum 
can  scarcely  be  said  to  form  an  exception  to  the  general 
rule  of  all  serous  membrane,  in  FIG.  174. 

being  a  shut  sac.  Its  structure 
is  the  same  as  all  other  serous 
membranes,  being  composed  of 
an  external  layer  of  cellular  tis- 
sue, and  an  internal  one,  which 
is  pearly  in  appearance,  smooth, 
semi-transparent,  and  by  the  mi- 
croscope is  shown  to  consist  of  la- 
mina3  of  flattened  vesicles,  with 
central  nuclei.  The  external  lay- 
er is  connected  with  the  sur- 
rounding structures,  and  con- 
ducts the  nutrient  vessels  and  „. 
nerves.  The  peritoneum  has 
two  great  divisions,  the  one 
lining  the  abdominal  walls  and 
called  its  parietal;  the  second 
reflected  over  the  viscera,  and 
called  its  visceral  portion.  As 

FIG.  174  represents  the  Reflections  of  the  Peritoneum.  1  Liver.  2  Stomach. 
3  Small  intestine.  4  Arch  of  the  colon.  5  Duodenum.  6  Pancreas.  7 
Rectum.  8  Uterus.  9  Vagina.  10  Bladder.  11  Peritoneum  reflected  from, 
diaphragm  to  Liver,  and  thence  to  the  lesser  curvature  of  the  stomach,  form- 
ing the  anterior  layer  of  the  omentum  minus,  then  12  covers  anterior  face  of 
stomach,  and  at  13  14  descends  to  form  the  omentum  majus ;  at  15  it  is  re- 
flected upward,  forming  at  16  the  posterior  layer  of  this  latter  omentum  ;  at  17 
it  surrounds  the  transverse  colon,  and  extends  back  to  the  spine,  forming  at  18 
the  mesocolon ;  it  now  goes  in  front  of  the  duodenum  5,  and  descends  to  the 
small  intestine  3,  which  it  surrounds  and  furnishes  the  mesentery  ;  it  next  de- 
scends the  posterior  abdominal  wall,  covering  the  rectum  7,  in  front,  the  uter- 
us 8,  bladder  10 ;  and  then  ascends  covering  the  anterior  abdominal  wall  20 
and  21,  to  the  diaphragm,  place  of  beginning,  at  22.  If  we  start  again  from  the 
diaphragm,  we  follow  the  peritoneum  forming  at  23,  the  posterior  layer  of 
lesser  omentum,  and  at  24  the  posterior  layer  of  the  stomach,  and  thence  down- 
ward, forming,  at  25  and  26,  the  posterior  layer  of  the  anterior  fold  of  omentum 
majus,  and  then  turns  up  at  27  to  constitute  the  anterior  layer  of  omentum, 
which  goes  to  the  anterior  surface  of  the  colon  4,  and  at  28  forms  the  anterior 
surface  of  the  meso-colon,  which  is  traced  up  to  the  pancreas  6,  and  on  to  the 
place  of  beginning. 


556 


PERITONEUM. 


this  membrane  is  a  shut  sac,  it  is  immaterial  where  we 
commence  tracing  it,  as  we  must  necessarily  return  to  the 
place  of  beginning.  If  we  start  at  the  umbilicus,  we  fol- 
low it  ascending  upon  the  internal  surface  of  the  anterior 
abdominal  walls,  to  the  diaphragm,  upon  the  lower  surface 
of  which  it  is  reflected.  From  the  diaphragm  it  passes  on 
the  left  side  upon  the  spleen,  on  the  right  to  the  liver,  and  in 
the  centre  upon  the  stomach.  In  this  course  from  the  um- 
bilicus there  is  also  a  distinct  reflection  to  the  convex  surface 
of  the  liver,  called  the  suspensory  or  falciform  ligament, 
which  receives  the  ligamentous  remains  of  the  umbilical 
vein.  There  are  other  reflections  of  this  membrane  upon  the 
liver,  which  will  be  noticed  in  the  separate  description  of  this 
viscus.  From  the  liver,  after  investing  both  surfaces,  it  is 
traced  from  the  transverse  fissure  downward  to  the  lesser 
curvature  of  the  stomach.  This  reflection  is  called  the  lesser 
omentum,  or  gastro-liepatic  omentum,  and  encloses  the  he- 
patic vessels ;  at  the  lesser  curvature  of  the  stomach,  the  two 
laminse  of  this  omentum  separate,  the  one  to  pass  in  front  of, 
and  the  other  behind  the  stomach,  to  meet  again  along  the 
greater  curvature,  thus  completely  investing  this  organ,  ex- 
cept at  the  upper  and  lower  curvatures,  where  this  mem- 
brane separates  and  again  unites.  From  the  greater  curv- 
ature of  the  stomach,  the  peritoneum  descends  to  the 
lower  part  of  the  abdomen,  and  then  turning  upon  itself, 
ascends  to  the  arch  of  the  colon,  thus  making  this  reflec- 
tion to  consist,  by  its  duplication,  of  four  lamina?.  It  is 
called  the  omentum  majus,  or  gastro-colic  omentum. 

At  the  colon  it  again  separates  to  enclose  this  intestine, 
and,  upon  the  concave  portion,  unites  to  pass  to  the  spine, 
forming  another  reflection,  called  the  transverse  mesocolon, 
which  divides  the  abdominal  cavity  into  two  parts — supe- 
rior and  inferior.  From  the  spine  the  transverse  mesocolon 
separates  into  an  ascending  and  descending  portion.  The 
former  is  traced  upward,  over  the  lower  part  of  the  duode- 
num and  the  pancreas,  to  the  posterior  part  of  the  right 
lobe  of  the  liver,  where  it  is  continuous  with  the  perito- 
neum of  this  organ,  and  the  posterior  layer  of  the  lesser 


PERITONEUM.  557 

omentum.  The  lower  or  descending  layer  passes  over  the 
small  intestines,  and  round  these  and  their  vessels,  to  form 
a  double  lamina,  which  returns  to  the  spine,  forming  a  very 
broad  and  important  reflection,  termed  the  mesentery.  The 
mesentery,  besides  blood-vessels,  also  encloses  numerous 
lymphatic  glands  and  absorbents.  From  the  root  of  the 
mesentery  we  find  its  laminae  stretching,  upon  either  side, 
into  the  lumbar  regions  upon  the  right  and  left  colon,  con- 
stituting the  right  and  left  mesocolons,  into  the  iliac  regions, 
and  thence  into  the  pelvis,  upon  the  rectum,  forming  the 
meso-rectum.  From  the  rectum,  of  which  it  does  not  cover 
more  than  its  upper  two-thirds,  it  is  reflected,  in  the  male, 
upon  the  posterior  and  lower  part  of  the  bladder,  forming 
two  lateral  folds,  called  the  posterior  ligaments  of  the  blad- 
der, between  which  there  is  a  depression  or  cul-de-sac. 

In  the  female  this  reflection  passes  first  to  the  posterior 
and  upper  part  of  the  vagina,  then  spreads  over  the  uterus 
and  to  either  side,  forming  the  broad  ligaments,  which  en- 
close the  Fallopian  tubes,  ovaries,  and  round  ligaments. 
From  the  front  of  the  uterus  the  reflection  proceeds  to  the 
bladder,  and  then  ascends,  as  in  the  male,  upon  the  sides 
and  posterior  surface  of  the  bladder,  to  its  fundus,  whence 
it  is  traced  upward,  upon  the  posterior  abdominal  walls,  to 
the  umbilicus — the  place  where  it  was  first  opened. 

In  this  tracing  of  the  peritoneum,,  it  is  seen  that  it  only 
gives  a  partial  covering  to  many  of  the  organs — as  the 
duodenum,  rectum,  bladder,  kidneys,  &c. ;  that  all  the  vis- 
cera, even  those  having  the  most  complete  investment  from 
it,  are  upon  its  external  surface,  and  not  within  its  cavity ; 
and  that  each  organ  gets  its  covering  by  simply  pushing 
this  membrane  before  it  into  the  peritoneal  sac.  A  famil- 
iar illustration  is  found  in  the  double  night-cap,  showing 
how  a  shut  sac  may  invest  any  thing,  yet  be  on  its  out- 
side. The  portion  of  the  cap  covering  the  head,  resembles 
the  peritoneum,  covering  the  viscera,  while  the  loose  part 
of  the  cap,  above  the  head,  resembles  the  reflected  portion 
of  the  peritoneum,  upon  the  abdominal  walls. 

About  the  neck  of  the  gall-bladder,  and  at  the  base  of 


558  THE  STOMACH. 

the  lobulus  Spigelii,  is  seen  a  large  opening,  called  the  fo- 
ramen of  Winslow.  It  is  by  this  foramen  that  the  cavity  of 
the  omentum  communicates  with  the  cavity  of  the  peri- 
toneum. If  air  he  forced  into  this  opening,  it  is  found  to 
pass  behind  the  stomach,  and  fill  the  cavity  of  the  omen- 
tum. Dr.  Hodge,  of  Philadelphia,  appears  to  be  the  first 
who  has  suspected  the  true  use  of  this  foramen,  which  is  to 
introduce  this  lining  lamina  of  the  great  omentum,  so  as  to 
make  it  duplicate  throughout.  Function. — The  peritoneum 
connects  the  several  abdominal  viscera,  and  retains  them 
in  their  natural  positions.  It  also  conducts  the  various 
blood-vessels  and  nerves,  and  secretes  a  fluid  by  which  its 
surfaces  are  lubricated,  and  friction  diminished. 

THE  STOMACH — (VENTRICTJLUS.) 

The  stomach  receives  the  masticated  and  insalivated  food 
from  the  oesophagus. 

This  organ  presents  the  largest  dilatation  of  the  aliment- 
ary canal.  It  occupies  the  epigastric,  left  hypochondriac, 
and  part  of  the  right  hypochondriac  region,  lying  between 
the  oesophagus  on  the  left,  and  the  duodenum  on  the  right, 
with  each  of  which  it  is  inseparably  connected.  It  has 
still  further  connections,  by  means  of  the  peritoneum,  to 
the  diaphragm  and  liver  above,  through  the  reflection  of 
the  omentum  minus ;  below,  to  the  arch  of  the  colon,  by 
the  omentum  majus ;  on  the  left,  with  the  spleen,  by  the 
omentum  gastro-splenicum. 

Its  shape  is  somewhat  conoidal,  with  the  base  on  the  left 
side,  whence  it  extends  obliquely  downward  and  forward, 
across  the  epigastric  region,  to  terminate  on  the  right  side, 
near  the  gall-bladder,  in  the  duodenum.  It  presents  two 
surfaces,  two  curvatures,  two  orifices,  and  two  extremities. 

The  surfaces,  are  anterior  and  posterior.  In  the  dis- 
tended state  of  the  stomach,  the  anterior  surface  becomes 
superior,  and  looks  towards  the  diaphragm,  being  in  con- 
tact with  the  ribs  and  left  lobe  of  the  liver.  The  posterior 
surface  presents  towards  the  spine.  The  curvatures  are  su- 
perior and  inferior,  or  lesser  and  greater.  The  lesser  extends 


THE  STOMACH. 


559 


FIG.  175. 


between  the  oesophagus  and  pylorus — presents  upward  and 
backward,  and  receives  the  omentum  minus.  The  greater 
looks  downward  and  forward,  and  has  the  omentum  majus 
attached  to  it.  Along  these  curvatures,  the  stomach  is  not 
covered  by  the  perito- 
neum, and  it  is  at  these 
points  that  the  separa- 
tion of  the  omentum 
occurs,  and  allow  of 
that  expansion  of  the 
stomach,  in  a  state  of 
distension,  which  it  is 
believed  to  be  their 
function  to  afford. 

A  variety  of  opinions 
have  been  entertained 
in  reference  to  the  use 
of  the  omentum  majus, 
into  which  we  shall 
not  stop  to  inquire,  and 
will  simply  remark,  in 
addition  to  what  has 
been  already  said,  un- 
der the  head  of  perito- 
neum, that  both  its 
position  and  density 
vary  very  much.  At 
one  time  it  is  found 
spread  out  as  an  apron,  over  the  intestines,  and  at  another, 
tucked  up  and  hid  by  the  stomach.  At  one  time  it  is 
very  thick,  from  being  loaded  with  fat — while  at  another, 
it  is  entirely  destitute  of  adipose  matter,  and  extremely 
thin  and  transparent. 

FIG.  175  represents  the  Stomach  and  Intestinal  Tube.  1  (Esophagus  laid 
open.  2  Cardiac  orifice  of  stomach.  3  Interior  of  stomach.  4  Duodenum 
commencing  at  the  pyloric  orifice  of  stomach.  5  Gallbladder.  6  6  6  Small 
intestine.  7  Coacum  or  beginning  of  large  intestine.  8  Appendix  vermifor- 
mis.  9  Right  ascending  colon.  10  Transverse  colon.  11  Left  descending 
colon.  12  Sigmoid  flexure.  13  Rectum.  14  Anus. 


560 


THE  STOMACH. 


The  orifices  of  the  stomach  are  the  cardiac  and  pyloric. 
The  cardiac  is  on  the  left  side,  and  forms  the  termination 
of  the  oesophagus  in  the  stomach.  The  pyloric  is  on  the 
right  side,  and  forms  the  entrance  to  the  duodenum.  It  is 
lower  than  the  cardiac,  and  is  readily  recognized  by  a  cir- 
cular thickening  of  the  parts. 

The  extremities  of  the  stomach  are  a  greater ',  which  is  in 
the  left  hypochondrium,  and  comprises  what  is  termed  the 
great  cul-de-sac,  which  is  situated  to  the  left  of  the  oeso- 
phagus, and  in  front  of  the  spleen.  The  lesser  is  the  pyloric 
extremity,  which  is  to  the  right,  much  smaller  than  the 
left,  of  a  cylindrical  shape,  and  extends  to  the  gall-bladder. 
The  size  of  the  stomach  varies  in  different  individuals, 
and  in  different  conditions  of  fullness  or  emptiness.  Its 
average  capacity  is  estimated  at  about  one  quart. 

Structure. — The  stomach  consists  of  membranous  tunics 

or  coats,  blood-ves- 
sels, and  nerves. 
The  proper  coats 
are  three,  a  serous, 
muscular,  and  mu- 
cous, to  which  is 
added  the  cellular, 
called  the  fibrous 
or  nervous  coat. 
The  serous  coat 
has  been  already 
described  as  be- 
ing a  reflection  of 
the  peritoneum, 
coming  from  the  omentum  minus,  and  forming  a  complete 
investment  of  the  stomach,  except  at  its  curvatures. 

The  muscular  coat  presents  three  layers  of  fibres,  which 
are  usually  pale,  though  variable  as  to  color.     The  first 

FIG.  176  represents  the  Coats  of  the  Stomach,  a  (Esophagus,  b  Cul-de- 
sac  of  stomach,  or  greater  extremity,  c  Pyloric  extremity,  d  Duodenum. 
e  e  Peritoneal  coat  turned  back.  /  Longitudinal  fibres  of  muscular  coat,  g 
Circular,  h  Oblique  fibres,  i  Portion  of  muscular  coat  of  duodenum. 


THE  STOMACH.  561 

layer  is  longitudinal;  it  is  seen  by  raising  the  serous  coat, 
Is  external,  and  extends  from  the  oesophagus,  with  the 
fibres  of  which  it  is  continuous,  and  thence  radiates  to- 
wards the  pylorus,  being  found,  in  greatest  abundance, 
along  the  lesser  curvature,  though  also  seen  upon  the  greater 
curvature  and  extremity.  The  second,  or  middle  layer,  is 
circular,  commencing  at  the  cardiac  end,  and  increasing,  in 
the  strength  and  number  of  its  fibres,  as  it  proceeds  to  the 
pylorus.  The  fibres  of  the  third  or  internal  layer  take  u-e 
oblique  course,  are  most  distinct  on  the  great  extremity, 
and  spread  over  the  anterior  and  posterior  surfaces  of  the 
stomach. 

The  third  or  proper  coat  of  the  stomach,  is  the  internal, 
•mucous,  or  villous.  This  is  connected  to  the  muscular  by 
an  intervening  structure,  termed  nervous  or  fibrous,  which 
consists  of  fibres  closely  united,  dense  and  strong,  and  re- 
garded as  the  frame-  F,G.  177. 
work  of  the  mucous 
membrane,  to  which 
it  gives  support,  and 
conducts  its  blood- 
vessels and  nerves. 
The  mucous  mem- 
brane is  a  continua- 
tion of  that  lining  the 
oesophagus,  and,  ac- 
cording to  the  obser- 
vations of  Dr.  Beaumont,  is  constantly  covered  with  a  vis- 
cid, transparent  mucus.  In  its  natural  state  it  is  of  a 
light  or  pale  pink  color,  varying,  however,  with  the  full- 
ness or  emptiness  of  the  stomach.  It  has  a  soft,  velvet-like 
appearance,  whence  its  name  the  villous  coat. 

When  deprived  of  its  mucus,  by  washing,  and  examined 
with  the  microscope,  in  water,  it  presents  a  honeycomb 

FIG.  177  represents  the  Interior  of  the  Stomach,  a  (Esophagus,  b  Cardiac 
orifice  of  the  stomach,  c  Its  cul-de-sac,  d  Greater  curvature,  e  Where 
omentum  majus  is  attached.  /  Muscular  coat,  g  Cut  edge  of  mucous  coat. 
k  Rugae  of  mucous  coat,  t  Lesser  curvature,  j  Where  duodenum  begins,  k 
Pyloric  orifice  and  valve.  I  Duodenum. 

36 


562 


THE  STOMACH. 


appearance,  exhibiting  numerous  depressions,  which  are 
termed  gastric  pits,  or  favuli.     These  pits  are  surrounded 
by  ridges,  forming  septa  between  them,  which  septa  are 
Fio.  ns.  described  as  consisting  of  condensed  cel- 

lular tissue,  and  containing  mucous  folli- 
cles, and  many  vessels.     Each  of  these 
gastric   pits  is  studded  with  foramina, 
four  or  five  in  number,  which  are  re- 
garded as  the  orifices  of  the  ducts,  lead- 
ing from  the  glands,  which  furnish  the 
gastric    juice.      These    gastric    glands    consist    of    coecal 
pouches,  or  follicles,  situated  in  the  sub-mucous  tissue; 
and  of  tubes,  some  of  which  are  short  and  straight,  others 
FIG.  179.         longer  and  convoluted,  all  closely  applied 
together,  and  terminating,  by  the  above 
foramina,  in  the  gastric  pits. 

Mr.  Beaumont  observes  that  "when  ali- 
ment or  any  irritant  is  applied  to  the 
surface,  innumerable  lucid  points  and  fine 
nervous  or  vascular  papillae  can  be  seen, 
arising  through  the'  mucous  coat,  from 
which  distils  a  pure,  limpid,  colorless, 
slightly  viscid  fluid.  This  is  invariably 
acid.  The  mucus  of  the  stomach  is  less 
fluid,  more  viscid,  semi-opaque,  a  little 
saltish,  and  has  no  acidity.  The  gastric 
fluid  is  never  accumulated  while  fasting, 
and  is  seldom,  if  ever,  discharged,  except 
under  the  excitement  of  food,  or  some  irri- 
tant. It  is  secreted  only  in  proportion 
to  the  quantity  of  food  supplied,  provided 
there  is  not  more  of  the  latter  than  the  sys- 
tem requires;  and  if  an  excess  of  food  be  taken,  the  residue 
either  remains  in  the  stomach,  or  passes  into  the  bowels  in 

FIG.  178  represents  the  Gastric  Favuli  on  the  inner  coat  of  the  stomach. 
*Fic    179  represents  the  Gastric  Glands  or  Follicles,     a  Glands  magnified 
three  times,     b  Magnified  twenty  times. 


THE  STOMACH.  565 

a  crude  state."  The  free  acid  of  this  fluid  is  the  hydro- 
chloric,* which,  in  combination  with  a  peculiar  animal 
matter,  called  pepsin,  is  believed  to  constitute  the  proper 
digestive  principle.  So  potent  is  this  principle  represented, 
that  the  sixty-thousandth  part,  in  acidulated  water,  im- 
parts to  it  digestive  properties. 

The  mucous  coat  also  presents  numerous  rugge,  folds  or 
wrinkles,  which  are  irregular  in  their  course,  size,  and 
shape.  The  most  prominent  run  in  the  long  diameter  of 
the  stomach,  and  nearly  parallel.  They  are  most  distinct 
about  the  pylorus.  The  texture  of  this  coat  is  soft,  easilj 
torn,  and  loose.  It  is  covered  by  epithelium,  which  is  more 
delicate,  thinner,  and  softer,  than  that  of  the  pharynx  or 
O3sophagus  with  which  it  is  continuous,  and,  unlike  these, 
has  the  cylindrical  instead  of  the  laminated  form. 

Where  the  stomach  ends  in  the  duodenum,  the  mucous 
coat  forms  a  fold  called  the  pyloric  valve;  around  this  valve 
the  circular  fibres  of  the  muscular  coat  collect  in  the  form 
of  a  bundle,  and  constitute  a  sphincter  muscle,  upon  which 
depends  all  the  efficacy  of  this  valve  in  closing  the  open- 
ing from  the  stomach  into  the  duodenum.  About  both  ex- 
tremities of  the  stomach,  the  mucous -coat  contains  glands 
which  resemble  those  of  Brunner.  They  are  thought  to 
furnish  mucus. 

Blood-vessels  of  the  Stomach. — The  arteries  are  the  gastric 
or  coronary,  which  comes  from  the  cardiac  axis,  and  runs 
along  the  upper  curvature ;  the  right  and  left  epiploic,  and 
the  vasa  brevia,  which  come  from-  the  hepatic  and  splenic 
arteries.  The  epiploic  arteries  run  along  the  greater  curv- 
ature, anastomosing  and  radiating  in  every  direction,  while 
the  vasa  brevia,  which  are  five  or  six  small  branches  from 
the  splenic,  pass  to  the  left  or  greater  end  of  the  stomach. 

The  corresponding  veins  enter  into  the  vena  portarum. 
The  nerves  are  the  pneumo-gastric,  and  the  sympathetic. 
The  former  form  a  plexus  around  the  cardiac  orifice  and  ex- 

*  Lehmann,  Bernard,  and  Baneswil  affirm  that  the  free  acid  is  lactic.  Prout, 
Dunglison.  Enderlin,  Leibig,  Bence  Jones,  and  Graham,  say  that  it  is  the. 
hydrochloric. 


564 


THE   INTESTINES. 


pand  upon  the  anterior  and  posterior  surfaces.  The^latter 
come  from  the  solar  plexus,  and  accompany  the  arteries- 
The  lymphatics  are  numerous  and  traced  to  the  glands 
along  the  curvatures. 

Function.— The  stomach  is  the  organ  in  which  and  by 
FlG-  18°-  which  is  performed 

the  first  and  most 
important  step  in  di- 
gestion, the  conver- 
sion of  the  food  into 
a  soft  grayish  homo- 
geneous, and  slight- 
ly acid  fluid  called 
chyme  ;  this  change 
is  effected  through 
the  agency  of  the 
gastric  fluid,  which 
is  brought  into  con- 
tact and  thoroughly  blended  with  every  particle  of  aliment, 
by  means  of  the  motion  communicated  to  both  through  the 
muscular  apparatus  of  the  stomach. 

THE  INTESTINES,  (Fig.  175.) 

The  intestines  comprise  the  whole  of  the  alimentary 
canal,  from  the  stomach  to  the  anus.  The  length  of  this 
canal  averages  from  thirty  to  thirty-five  feet,  though  it 
measures  more  when  separated  from  its  connections  and 
stretched  out.  Its  size  varies,  and  its  shape  is  cylindrical. 
The  intestines  are  divided  into  the  small  and  large  intestine. 

The  small  intestine  is  subdivided  into  the  duodenum,  the 
jejunum,  and  the  ilium. 

The  large  intestine  into  the  coecum,  the  colon,  and  the 
rectum. 

FIG.  180  represents  the  Arteries  of  the  Stomach  and  its  relation  to  the 
liver,  pancreas,  spleen,  and  duodenum.  1  Liver.  2  Stomach.  3  Duodenum. 
4  Pancreas.  5  Spleen.  6  Cardiac  artery.  7  Gastric  artery.  8  Hepatic  ar- 
tery. 9  Pyloric.  11  Right  gastro  epiploic.  17  Left  gastro  epiploic.  13 
Cystic.  14  Splenic.  15  Pancreatic.  16  Vasa-brevia.  18  Superior  mesen- 
teric  artery. 


THE  DUODENUM.  565 

The  small  intestine  reaches  from  the  pylorus  to  the 
ilio-co3cal  valve  in  the  right  iliac  region.  It  is  about  an 
inch  in  diameter,  is  very  much  convoluted,  and  occupies 
principally  the  umhilical  and  hypogastric  regions. 

The  large  intestine  is  much  greater  in  size  than  the 
small,  though  only  ahout  one  fifth  of  its  length,  and  ex- 
tends from  the  right  iliac  region  to  the  anus,  occupying  the 
most  of  the  abdominal  regions,  and  surrounding  the  small 
intestine  like  a  ruffle.  The  whole  of  the  intestinal  canal 
has  the  same  number  of  coats  as  the  stomach ;  serous,  mus- 
cular, cellular  and  mucous.  There  are  some  differences, 
however,  in  this  canal,  which  we  shall  briefly  notice  under 
its  respective  divisions. 

THE  DUODENUM. 

The   duodenum,    so   called   from  being  twelve  fingers' 
breadth  in  length,  is  the  shortest  portion  of  the  small  in- 
testine, though  it  has  the  greatest  capacity.     It  is  situated 
PIG>  IQI  in  the  right  hypochondriac,  right 

lumbar,  and  portion  of  the  um- 
bilical  regions.  It  takes  a  semi- 
circular course.  Commencing  at 
the  pylorus,  it  ascends  to  the 
under  surface  of  the  liver,  then 
makes  a  turn  called  its  superior 
angle,  and  descends  vertically  in 
front  of  the  right  kidney  as  low 
as  the  third  lumbar  vertebra,  where  it  makes  a  second  turn, 
the  inferior  angle,  then  passes  to  the  left  side  of  the  second 
lumbar  vertebra,  crossing  the  spine,  and  beneath  the  su- 
perior mesenteric  artery,  terminates  in  the  jejunum.  In 
consequence  of  its  great  dilatation,  it  has  by  some  been 
regarded  as  a  second  stomach. 

The  peritoneal  coat  of  the  duodenum  furnishes  a  complete 

FIG.  181  represents  the  Interior  of  Duodenum  and  a  portion  of  the  Stomach. 
a  a  Pyloric  end  of  stomach.  6  6  Folds  and  follicles  of  the  mucous  coat  of  the 
stomach,  c  Looks  into  the  pylorus,  d  Thickness  of  pylorus,  e  e  Rugae  of  mucous 
coat  of  duodenum.  /  Point  of  entrance  of  the  ductus  communis  choledochus. 


566  THE  DUODENUM. 

covering  only  at  the  superior  part,  the  inferior  and  trans- 
verse portions  simply  lying  between  the  laminas  of  the 
mesocolon,  without  any  proper  serous  investment.  By  this 
arrangement  the  superior  portion  of  the  duodenum  only  is 
movable,  the  rest  being  fixed.  In  the  circuit  it  makes,  it 
encloses  the  head  of  the  pancreas,  and  at  the  posterior  part 
of  its  second  curve,  the  ductus  communis  choledochus,  or  the 
common  biliary  and  pancreatic  duct,  is  seen  to  enter. 
This  duct  sometimes  enters  as  two  separate  tubes,  and 
passes  in  either  case  very  obliquely  through  the  coats  of 
the  duodenum. 

The  muscular  coat  has  two  sets  of  fibres ;  the  one  longi- 
tudinal, thinly  scattered  and  superficial,  the  second  inter- 
nal, with  its  fibres  arranged  more  closely  together,  so  as  to 
form  a  more  perfect  layer.  They  run  circularly,  though 
none  surround  the  tube  completely,  forming  only  segments 
of  circles.  The  muscular  coat  is  rather  pale  and  thin, 
though  its  color  is  deeper  than  that  of  any  other  portion  of 
the  small  intestine. 

The  mucous  coat  presents  on  its  surface  a  series  of  folds 
or  processes  termed  valvulce  conniventes,  which  are  perma- 
nent elevations  of  this  membrane,  and  unlike  the  rugae  of 
the  stomach,  which  are  only  accidental,  are  not  effaced  by 
distension.  At  the  lower  part  of  the  duodenum  they  are 
large  and  numerous,  while  they  are  few  in  number  and 
small  at  the  upper  portion.  They  represent  a  succession  of 
arches  or  duplications  of  the  mucous  coat,  nearly  parallel 
to  each  other,  running  round  the  tube  in  almost,  though 
not  entirely  perfect  circles,  about  three  lines  in  breadth, 
though  generally  wider  in  the  middle,  and  having  their 
extremities  frequently  bifurcated.  These  valvulse  greatly 
increase  the  extent  of  the  absorbing  surface  of  the  chyle, 
and  serve  to  retard  the  food  in  its  downward  passage,  so 
that  ample  time  shall  be  allowed  for  the  extraction  of  all 
nutritious  matter. 

On  the  mucous  coat  are  also  seen  numerous  little  pro- 
cesses resembling  the  down  upon  the  cuticle  of  an  unripe 
peach,  and  hence  called  mill.  They  are  described  as  being 


THE  DUODENUM.  567 

from  one  fourth  to  a  line  in  length,  and  estimated  by 
Meckel  to  be  about  four  thousand  to  the  square  inch. 
These  villi  present,  under  the  microscope,  FIG.  182. 
a  foliated  or  fungiform  appearance,  covered 
by  epithelium,  and  containing  a  minute 
plexus  of  blood-vessels,  and  a  lacteal  tube, 
all  united  by  cellular  tissue. 

The  lacteal  forms  the  prominent  part  of | 
each  villus.  It  commences,  in  the  apex  of 
the  latter,  by  delicate  branches,  converging  I 
to  a  single  trunk,  which  proceeds  to  the  base  of  the  villus, 
and  there  unites  with  similar  tubes  from  other  villi. 
It  is  not  yet  fully  settled  whether  the  lacteals  begin  by 
open  orifices,  or  by  anastomosing  loops.  The  latter  opin- 
ion is  most  strongly  urged,  though  observations  are  not 
wanting  to  prove  the  existence  of  both  arrangements. 
Those  who  deny  that  there  are  any  open  mouths,  explain 
the  absorption  of  the  chyle,  on  the  principle  of  endosmosis. 

At  the  extremity  of  each  villus,  a  mass  of  minute  cells  is 
described  by  Mr.  Goodsir,  as  surrounding  the  loops  of  the 
lacteals.  He  regards  them  as  true  agents  of  absorption, 
first  receiving  the  chyle,  and,  on  becoming  distended, 
transferring  their  contents,  by  solution  or  deliquescence,  to 
the  lacteals.  It  has  been  observed  that,  during  digestion, 
these  cells  become  erect  and  turgid  with  chyle,  while  in 
the  interval  they  are  found  relaxed  and  empty,  and  pre- 
sent the  appearance  of  a  collection  of  granular  germs. 
These  cells  are  short-lived,  being  constantly  destroyed,  and 
as  constantly  renewed. 

Tbe  mucous  coat  of  the  duodenum,  besides  the  simple 
follicles  of  Lieberkuhn,  scattered  every  where  throughout 
the  mucous  tissue,  contains  also  the  glands  of  Brwiner, 
(Fig.  183.) 

These  glands,  situated  in  the  sub-mucous  tissue,  sur- 
round this  intestine  in  the  form  of  a  layer  of  white  bodies 
of  the  size  of  hemp-seed,  and  of  oval  form.  Each  is  said 
to  contain  several  hundred  follicles  whose  excretory  ducts, 

FIG.  182  represents  a  Villus  and  the  commencement  of  a  Lacteal. 


568  JEJUNUM  AND  ILIUM. 

like  those  of  the  sublingual  gland,  discharge   separately 
FIG.  183.     into   the  duodenum.     The  secretion   of  these 
glands  is  supposed  to  be  like  that  of  the  pan- 
creas or  salivary  glands. 

The  arteries  of  the  duodenum  come  from  the 
hepatic,  splenic,  and  superior  mesenteric.  The 
veins  go  to  the  vena  portae.  The  nerves  come 
from  the  solar  plexus. 
Function. — The  duodenum  completes  the  process  of  diges- 
tion, by  changing  the  chyme,  formed  in  the  stomach,  into 
chyle,  and  this  by  means  of  the  bile  and  pancreatic  juice 
poured  into  it  from  the  liver  and  pancreas,  through  the 
common  duct — the  ductus  communis  choledoclius. 

The  operation  of  the  bile  upon  the  chyme,  is  to  separate 
it  into  three  portions — one  falls  to  the  bottom,  as  a  reddish 
brown  sediment — another  occupies  the  top,  as  a  creamy 
pellicle,  while  the  third  remains  in  the  centre,  like  fluid 
whey. 

The  action  of  the  pancreatic  fluid,  about  which  there  has 
been  nothing  but  conjecture,  seems  to  be  pretty  fairly  de- 
termined by  the  recent  experiments  of  M.  Bernard,  which 
go  to  show  that  this  fluid  decomposes,  and  holds  in  solu- 
tion the  fatty  matters  of  the  chyme,  an  effect,  he  asserts, 
which  neither  gastric  juice,  bile,  saliva,  nor  any  other  agent 
can  produce.*  It  is  by  the  conjoint  action  of  these  two 
fluids  upon  the  chyme,  that  another  fluid,  of  the  color  and 
consistence  of  milk,  is  formed,  called  chyle,  which  is  taken 
up  by  the  lacteals  of  the  villi,  and  introduced  into  the 
system. 

THE   JEJUNUM   AND   ILIUM. 

The  jejunum,  (jejunus,  empty,)  so  called  from  being  found 
frequently  empty;  and  the  ilium,  (from  «x«v.  to  twist,) 
are  situated  in  the  umbilical,  hypogastric,  and  iliac  regions. 
The  jejimum  commences  in  the  left  lumbar,  and  the  ilium 

Fie.  183  represents  one  of  the  Glands  of  Brunner.  as  seen  at  the  commence- 
ment of  the  duodenum — magnified  a  hundred  times. 
*  See  Ohio  Medical  and  Surgical  Journal,  Vol.  1,  No.  1,  page  6J,  1848. 


JEJUNUM  AND  ILIUM. 


569 


FIG.  184.        A 


B 


ends  in  the  right  iliac  re- 
gion. There  is  no  natural 
division  showing  where 
one  of  these  intestines 
terminates,  and  the  other 
hegins.  The  upper  two- 
fifths,  however,  are  gener- 
ally assigned  to  the  jeju- 
num, and  the  lower  three- 
fifths  to  the  ilium.  These 
intestines  are  very  much 
coiled  on  each  other,  and 
are  convex  in  front,  and 
concave  behind,  where 
they  are  attached 
to  the  mesentery. 
The  serous  coat 
forms  a  complete 
covering  to  these 
intestines,  except 
at  the  small  trian- 
gular space  where 
the  hlood- vessels 
enter;  consequent- 
ly there  is  free- 
dom of  motion, 
though  both  are 
kept  in  their  natu- 
ral places  by  their 
connection  with 
the  mesentery. 


FIG.  184,  A  represents  a  section  of  the  lower  portion  of  the  Ilium,  and  com- 
mencement of  the  Colon,  a  a  Ascending  colon.  66  Ccecum,  or  caput  coli. 
cc  Lower  portion  of  the  ilium,  d  d  Muscular  coat,  e  e  Cellular  and  mucous 
coats.  // Folds  of  mucous  coat  at  the  beginning  of  the  colon,  gg  Cellular 
coat  prolonged  into  the  folds,  h  h  llio-colic  valve,  i  i  Where  the  coats  of 
the  ilium  and  colon  unite. 

FIG.  184,  B  represents  the  Mesentery,  a  a  Mesentery  suspended.  6  6  b 
Small  intestine,  c  Mesenteric  glands. 


5  TO  JEJUNUM  AND  ILIUM. 

The  mesentery  (Fig.  184  B,)  is  a  duplication  of  the  perito- 
neum, having  its  root  at  the  spine,  about  six  inches  in 
length,  and  extending  obliquely  from  the  second  lumbar 
vertebra  on  the  left,  to  the  right  iliac  fossa.  On  the  cir- 
cumference of  this  reflection  are  placed  the  intestines, 
while  between  its  laminae  are  found  the  blood-vessels, 
nerves,  lymphatic  glands,  and  lacteals. 

The  muscular  coat  is  not  so  strong  as  in  the  duodenum, 
though  it  is  thought  the  two  sets  of  fibres  are  more  dis- 
tinctly made  out.  They  are  pale  and  thin  as  in  the  duode- 
num. The  longitudinal  set  shortens  the  tube,  while  the 
circular  set  constricts  or  lessens  its  diameter;  the  former  pro- 
ducing the  peristaltic,  the  latter  the  vermicular  motion  of 
the  bowels.  The  conjoint  action  of  the  two  carries  on,  step 
by  step,  the  contents  of  this  tube. 

The  mucous  coat  presents  thevalvulee  conniventes  through, 
the  whole  of  the  jejunum,  more  prominent  than  in  the  duo- 
denum. These  valves  decrease  as  they  descend,  till  in  the 
lower  part  of  the  ilium  for  about  two  or  three  feet  they  are 
entirely  absent.  The  mucous  follicles  are  abundant  and 
exist  every  where,  as  in  the  duodenum  and  stomach,  pre- 
senting the  usual  cribriform  appearance.  The  glands  of 
Peyer  seem  peculiar  to  the  ilium,  and  are  chiefly  found  at 
its  lower  part  and  opposite  the  mesentery.  They  are  seen 
in  clusters  called  glandulcc  agminatce,  (Fig.  25,)  and  present 
patches  of  small,  white,  circular  raised  spots,  varying  in 
size  from  a  few  lines  to  as  many  inches  in  length,  and  from 
eight  to  twelve  lines  in  breadth. 

These  clusters  are  mostly  elliptical  in  their  shape,  and 
as  many  as  thirty  of  them  have  been  recognized  in  the 
ilium,  coming  nearer  and  nearer  to  each  other  as  they  ap- 
proach the  termination  of  this  intestine.  The  circular  spots 
composing  these  clusters  have  few  if  any  villi  over  their 
surface,  but  each  one  of  them  is  observed  to  be  surrounded 
by  a  circle  of  minute  openings  leading  to  the  follicles  of 
Lieberkuhn.  There  seems  to  be  no  connection  between 
these  follicles  and  the  glands  of  Peyer,  as  the  latter  have 
no  opening  or  excretory  duct ;  but  on  being  ruptured  are 


THE   LARGE  INTESTINE. 


571 


found  to  be  cavities  containing  mucus  and  small  cells  in 
different  stages  of  development. 

Blood-vessels  of  Jejunum  and  Ilium. — The  arteries  come 
from  the  superior  mesenteric.  The  veins  go  to  the  vena 
portas.  The  nerves  are  from  the  solar  plexus. 

Function.— The  absorption  of  chyle  by  the  lacteals,  orig- 
inating in  the  various  villi  on  the  mucous  surface  of  these 
intestines,  seems  to  be  their  great  duty.  These  villi  becom- 
ing less  and  less  numerous  as  we  pass  from  the  jejunum, 
the  lacteals,  and  consequently  the  absorption  of  chyle,  are 
found  to  diminish  in  like  proportion. 

THE   LARGE   INTESTINE. 

The  large  intestine  is  from  five  to  eight  feet  in  length, 
and  forms  about  one  fifth  of  the  intestinal  canal.  It  is 
divided  into  the  coecum,  colon,  Fie.  185. 

and  rectum.  It  commences  in 
the  right  iliac  region  where 
the  ilium  ends,  and  ascends 
through  the  right  lumbar,  to 
the  right  hypochondriac,  then 
crosses  the  lower  border  of 
the  epigastric  and  the  upper 
edge  of  the  umbilical  to  the 
left  side,  into  the  left  hypo- 
chondriac region,  whence  it 
descends  through  the  left 
lumbar  and  left  iliac  regions, 
^o  terminate  in  the  rectum. 

This  intestine  is  seen  thus  to 
traverse  all  the  abdominal  re- 
gions, and  to  form  nearly  a 

complete  circuit  enclosing  the  small  intestine.  It  has  the 
same  number  of  coats  as  the  small  bowel.  The  peritoneum 

FIG.  185  represents  the  Large  Intestine,  a  Termination  of  ilium.  6  Ap- 
pendix vermiformis.  c  Caput  coli  or  ccecum.  d  Transverse  colon,  e  De- 
scending colon.  /  Sigmoid  flexure,  g  h  Commencement  and  course  of  rectum. 
i  Anus. 


572  THE  LARGE  INTESTINE. 

gives  only  a  partial  covering,  and  is  studded  all  along  the 
large  intestine  with  little  reflections  containing  fat,  called 
appendices  epiploicce.  In  the  ascending  and  descending 
colons,  the  peritoneal  reflections  are  such  as  to  receive  the 
names  of  right  and  left  mesocolon.  The  arch  of  the  colon  is 
almost  entirely  surrounded,  has  great  facility  of  motion, 
and  is  kept  in  its  place  "by  the  reflection  termed  transverse 
mesocolon.  This  reflection  goes  back  to  the  spine  and 
divides  the  abdominal  cavity  into  two  parts,  thus  separating 
the  stomach,  liver,  and  spleen  above,  from  the  intestines 
below.  The  rectum  is  kept  in  position  by  the  reflection 
termed  meso-rectum. 

The  muscular  coat  differs  from  that  of  the  small  intes- 
tine, in  having  its  longitudinal  fibres  collected  into  three 
bands,  which  are  equi-distant  and  about  an  inch  in  breadth; 
one  of  these  bands  is  anterior,  another  internal,  and  the 
third  external.  These  are  white,  strong,  and  elastic,  and 
being  shorter  than  the  other  coats,  produce  constrictions  in 
its  course,  giving  to  this  intestine  a  cellular ,  sacculated,  or 
pouch-like  appearance.  These  cells  or  pouches  disappear 
when  the  bands  are  divided.  These  delay  the  too  rapid 
passage  of  the  faeces. 

The  mucous  coat  differs  from  that  of  the  small  intestine 
in  being  almost  if  not  entirely  destitute  both  of  villi  and 
valvulae  conniventes.  The  rugge  that  are  seen  on  its  sur- 
face do  not  belong  to  the  mucous  coat  alone,  but  are  formed 
by  the  other  coats.  Each  of  the  different  divisions  of  this 
intestine  has  peculiarities  requiring  separate  notice. 

The  coecum,  (Fig.  1843  A)  securely  fastened  in  the  right 
iliac  fossa  by  the  peritoneum,  is  from  an  inch  to  two  inches 
in  length,  rounded  below  and  convex  externally. 

From  its  posterior  inferior  portion  on  the  left  side,  it 
gives  off  a  tortuous  process,  called  appendix  vermiformis, 
about  the  size  of  a  goose  quill,  and  varying  in  length  from 
three  to  six  inches.  Its  position  also  varies.  It  has  a 
peritoneal  covering  which  allows  it  to  float  loosely,  and 
it  is  sometimes  the  cause  of  much  mischief  by  surround- 
ing the  ilium  and  producing  strangulation.  It  is  tubular. 


THE  LARGE  INTESTINE.  573 

having  a  diameter  of  two  or  three  lines,  is  composed  of 
similar  structures  with  the  rest  of  the  intestine,  and  com- 
municates with  the  coecum  by  a  somewhat  valvular  ar- 
rangement. The  use  of  this  appendix  is  unknown. 

The  coecum  is  joined  on  its  left  side,  at  an  acute  angle, 
by  the  ilium.  The  ilium  seems  to  perforate  the  coecum, 
and  at  its  point  of  entrance  presents  a  transverse  elliptical 
slit  about  an  inch  in  length,  (Fig.  184,  A,)  having  access- 
ory fibres  called  retinacula,  to  strengthen  its  extremities. 
The  sides  of  this  slit  constitute  folds  or  valves  ;  the  inferior 
or  ilio-coecal,  and  the  superior  or  ilio-colic  valve.  The  for- 
mer prevents  regurgitation  from  the  coecum,  and  the  latter 
from  the  colon  into  the  ilium.  This  valve  consists  of  two 
layers  of  mucous  tissue  investing  cellular  and  muscular 
fibres,  and  is  formed  by  the  mucous  coat  and  circular  fibres 
of  the  ilium  protruding  through  a  separation  in  the  circu- 
lar fibres  of  the  ccecum.  It  looks  downward. 

The  colon  (Fig.  185)  is  a  continuation  of  the  coecum  up- 
ward, and  is  divided  into  the  ascending,  transverse,  descend- 
ing, and  sigmoid  flexure.  Its  course  and  connections  have 
already,  to  some  extent,  been  given  ;  and  it  may  be  further 
added  that  the  ascending  colon  passes  in  front  of  the  right 
kidney,  bordering  the  duodenum  on  the  left,  to  the  under 
surface  of  the  liver,  where,  by  its  connection  with  the  gall- 
bladder, it  is  frequently  tinged  with  bile ;  thence  it  makes 
its  arch  (transverse  colon)  across  the  abdomen,  being  bounded 
above  by  the  stomach,  and  below  by  the  small  intestine. 
On  the  left  it  descends,  being  hid  by  the  small  intestine  in 
front,  and  resting  upon  the  kidney,  it  terminates  in  the  left 
iliac  region  by  a  curve  which  goes  first  upward,  then  by 
one  or  more  coils  downward,  to  the  sacro-iliac  symphysis, 
where  it  ends  in  the  rectum.  This  curve  is  called  the  sig- 
moid  flexure.  It  is  covered  by  a  reflection  of  the  peritoneum, 
allowing  it  frequently  to  be  quite  loose,  and  giving  it  con- 
siderable motion. 

The  rectum,  (Fig.  185,)  so  called  from  its  straight  course, 
is  not  so,  strictly  speaking,  for  commencing  at  the  left  ilio- 
sacral  articulation,  where  the  sigmoid  flexure  terminates, 


5*74  THE  LARGE  INTESTINE. 

it  proceeds  obliquely  downward,  in  the  pelvis,  to  the  mid- 
dle line  of  the  sacrum,  at  the  lower  end  of  which,  accord- 
ing to  Mr.  Harrison,  it  hends  forward  towards  the  peri- 
neum, then  backward  and  downward,  to  end  in  the  anus, 
about  an  inch  or  more  from  the  coccyx.  It  presents,  there- 
fore, a  curvature  both  in  the  lateral  and  antero-posterior 
directions.  The  course  of  this  intestine,  however,  varies, 
and,  in  the  foetus,  is  almost  invariably  found  straight, 
owing,  doubtless,  to  the  straight  direction  of  the  spine  at 
that  period. 

The  size  of  the  rectum  varies ;  small  above,  it  expands 
below,  just  within  the  anus,  into  a  wide  pouch,  which  is 
not  cylindrical,  but  flattened  in  front.  In  the  male  the 
rectum  has  the  bladder,  prostate  gland,  and  vesicuhe  sem- 
inales,  on  its  anterior  surface ;  while,  in  the  female,  on  the 
same  surface,  are  the  vagina  and  uterus. 

The  peritoneum  surrounds  this  intestine,  only  at  its 
upper  third,  fixing  it  to  the  sacrum  behind,  by  a  reflection 
termed  meso-rectum.  In  its  middle  there  is  only  a  partial 
covering  in  front  and  at  the  sides — while  at  its  lower  por- 
tion, or  inferior  third,  it  is  entirely  destitute  of  serous 
membrane,  which  is  reflected  from  this  point,  upon  the 
bladder  in  the  male,  and  uterus  in  the  female,  forming, 
in  each  case,  a  pouch,  or  cul-de-sac,  at  the  place  of  re- 
flection. 

The  muscular  coat  of  the  rectum  increases  in  thickness/ 
and  exceeds  greatly  that  of  any  other  portion  of  the  intes- 
tinal canal.  The  longitudinal  layer,  which  exists  as  bands 
in  the  colon,  spreads  out  and  multiplies,  and  forms  a  complete 
tunic  for  the  rectum ;  and  the  circular  layer  also  increases 
in  strength  and  redness,  in  its  descent,  till,  at  the  anus, 
its  fibres  become  collected  in  a  circular  bundle,  constituting 
the  internal  sphincter  ani  muscle.  There  are  also  some  mus- 
cular fibres,  surrounding  the  anus  immediately  beneath 
the  integument,  termed  the  external  or  cutaneous  sphincter. 
Dr.  Homer  describes  the  longitudinal  fibres,  when  they 
have  reached  the  lower  border  of  the  internal  sphincter, 
as  turning  under  this  border,  between  it  and  the  external 


THE  LARGE  INTESTINE. 


sphincter,  and  then  ascending  for  an  inch  or  two,  in  con- 
nection with  the  mucous  coat  and  its  cellular  structure, 
into  which  they  are  inserted.  This  arrangement  explains 
the  protrusion  of  the  mucous  coat  in  prolapsus  ani. 

The  mucous  coat  is  thick  and  red,  presenting  at  the  upper 
portion  of  the  rectum  rather  a  smooth  surface,  while  at  the 
lower  are  seen  longitudinal  folds  called  columns,  which 
allow  of  the  distension  of  this  intestine,  and  also  some 
transverse  folds  which  are  not  regular  as  to  numher  or 

FIG.   186. 


size.  At  the  lower  end  of  the  columns,  and  between  them, 
pouches  are  observed,  (Fig.  186.)  A  radiated  wrinkling  is 
seen  around  the  anus,  which  is  formed  by  the  contraction 
of  the  external  sphincter.  The  margin  of  the  anus  is  sup- 
plied with  sebaceous  follicles,  and  the  whole  mucous  coat  of 
the  rectum  abounds  with  mucous  follicles. 

The  arteries  of  the  large  intestine  are  branches  of 
the  superior  and  inferior  mesenteric,  and  of  the  internal 
pudic  arteries.  Its  veins  enter  into  the  vena  porta?.  The 
solar  and  hypogastric  plexus  of  the  sympathetic  supply  it 
with  nerves. 

FIG.  186  represents  a  Section  of  the  Anus  and  Rectum,  showing  the  rectal 
pouches,  a  a  Columns  of  the  rectum,  b  b  Rudiments  of  columns,  c  Inter- 
nal sphincter  divided,  d  External  spincter  divided.  t  e  Folds  of  skin  on  the 
Bates.  /  Pouches,  g  Brisiles  in  the  pouches. 


5*76  THE  LIVER. 

Function. — To  act  as  a  reservoir  for  the  ftecal  matter, 
seems  to  be  the  principal  use  of  the  large  intestine.  But 
that  it  also  possesses  the  power  of  absorption  is  proved  by 
the  fact  of  patients  being  sustained  for  weeks  solely  by  in- 
jections of  nutritious  fluids  into  the  rectum. 

ASSISTANT   ORGANS   OF   DIGESTION,    OR   COLLATITIOUS  VISCERA. 

The  Liver,  (hepar.) — The  liver  is  justly  regarded  as  one 
of  the  most  important  organs  in  the  body,  on  account  of 
FIG.  187.  the  very  extensive 

influence  it  exerts, 
both  in  health  and 
disease. 

It  is  situated,  as 
already  stated,  in 
the  right  hypo- 
chondriac, extend- 
ing across  the  an- 
terior and  upper 
portion  of  the  epi- 
gastric, and  occupying  a  portion  also  of  the  left  hypochon- 
driac region.  Thus  placed,  it  is  of  course  below  the  dia- 
phragm, to  which  it  is  attached  by  reflections  of  the  peri- 
toneum, termed  ligaments. 

These  ligaments  are  five  in  number.  The  falciform  or 
suspensory  extends  from  the  umbilicus,  obliquely  upward 
along  the  linea  alba  and  the  right  side,  to  the  diaphragm 

FIG.  187  represents  the  inferior  surface  of  the  Liver,  a  Right  lobe.  6  Left 
lobe,  c  Anterior  thin  margin,  d  Posterior  thick  margin,  e  Right  extremity. 
j  Left  extremity,  g  Notch  on  anterior  margin,  h  Longitudinal  or  umbilical 
fissure,  i  Round  ligament,  j  Portion  of  suspensory  ligament,  k  Pons  or 
bridge  across  umbilical  fissure.  I  Posterior  extremity  of  longitudinal  fissure. 
m  n  Where  ductus  venosus  joins  the  inferior  vena  cava.  o  Transverse  fissure. 
p  Section  of  hepatic  duct,  q  Hepatic  artery,  r  Branches  of  latter,  s  Vena 
portarum.  t  Division  into  right  and  left  sinus  vena  portarum.  u  Remains  of 
ductus  venosus.  v  Gall-bladder,  w  Its  neck,  x  Lobulus  quartus.  y  Lobu- 
lus  spigelii.  z  Lobulus  caudatus.  a  a  Inferior  vena-cava.  6  6  Curve  of  liver. 
c  c  Depression  for  right  kidney,  d  d  Surface  over  renal  capsule,  e  e  Portion 
of  liver  uncovered  by  peritoneum.  //Coronary  ligament,  gg  Depression 
for  the  vertical  column. 


THE  LIVER. 

with  which  it  is  connected  by  its  convex  border,  while  its 
lower  or  concave  edge  is  fixed  to  the  upper  surface  of  the 
liver.  Along  the  inferior  margin,  and  enclosed  within  its 
fold,  is  a  cord,  called  the  ligamentum  teres';  this  was  formerly 
the  umbilical  vein  of  the  foetus,  now  obliterated  and  converted 
into  a  closed  ligamentous  cord.  It  passes  into  the  anterior 
notch  of  the  liver.  The  third  and  fourth  ligaments  are  the 
right  and  left  lateral.  The  former  is  reflected  from  the  pos- 
terior part  of  the  diaphragm  to  the  posterior  margin  of  the 
right  lobe.  The  left  lateral  comes  from  the  same  part  of 
the  diaphragm  and  goes  to  the  posterior  margin  of  the  left 
lobe.  The  coronary  ligament  is  described  as  extending  from 
the  suspensory  towards  the  lateral  ligaments,  and  as  con- 
sisting simply  of  the  lateral  extension  of  the  former. 

The  liver  lies  in  the  concavity  of  the  diaphragm,  and  is 
protected  by  the  seven  or  eight  inferior  ribs.  Below  it  is 
bounded  by  the  stomach  and  duodenum,  with  which  it  is 
connected  by  the  omentuin  minus ;  on  the  left  is  found  the 
spleen,  and  behind  are  the  ascending  or  inferior  cava  and 
vertebral  column. 

The/orm  of  tlie  liver  has  been  compared  to  an  ovoid  cut 
in  the  direction  of  its  long  axis.  Its  average  length  is 
from  ten  to  twelve  inches,  and  its  width  from  six  to  seven 
inches.  The  weight  is  from  three  to  five  pounds,  though 
all  these  measurements  are  liable  to  great  variation.  Its 
color  is  usually  a  reddish  brown,  not  unfrequently  inter- 
spersed with  dark  patches,  especially  on  the  lower  surface, 
which  however  are  not  morbid.  The  color  of  the  liver,  in- 
deed, varies  as  much  as  its  weight  and  length.  It  is  forihd 
red  in  the  very  young,  and  pale  and  yellow  in  the  old.  Its 
consistence  is  no  less  variable.  It  is  generally  firm,  dense, 
and  resisting,  sometimes  very  hard  and  friable ;  then  again 
quite  soft,  so  much  so  as  to  break  readily  under  pressure  of 
the  fingers.  This  latter  condition  is  often  owing  to  a  fatty 
degeneration. 

The  surfaces  of  the  liver  are  superior  and  inferior.     The 
superior  or  upper  surface  is  convex  and  smooth,  fits  in  the 
concavity  of  the  diaphragm,  and  is  divided  by  the  sus- 
37 


578  THE  LIVER. 

pensory  ligament,  from  front  to  back,  into  two  unequal 
portions. 

The  lower  surface  is  very  irregular,  being  marked  by 
several  eminences 'and  depressions,  or  fissures.  Eunning 
from  the  notch  in  the  anterior  edge  of  the  liver  backward,  on 
a  line  corresponding  with  the  direction  of  the  suspensory 
ligament,  is  the  umbilical  or  horizontal  fissure,  containing 
in  its  anterior  portion  the  obliterated  umbilical  vein,  and 
in  its  posterior  the  remains  of  the  ductus  venosus.  This 
fissure  divides  the  liver  into  its  right  and  left  lobes,  and  is 
sometimes  converted  at  its  anterior  part  into  a  complete 
tube,  by  a  portion  of  the  substance  of  the  liver  crossing  it 
after  the  manner  of  a  bridge  and  connecting  its  edges. 

The  transverse  fissure,  situated  near  the  centre  of  the 
lower  surface,  is  quite  broad,  about  two  inches  in  length, 
and  crosses  the  umbilical  at  right  angles.  It  contains  the 
hepatic  artery  and  duct,  the  vena  portarum,  lymphatics  and 
nerves,  and  cellular  tissue  which  bind  all  these  together. 

The  right  lobe  is  much  the  largest,  and  contains  nearly  the 
whole  of  the  transverse  fissure.  Proceeding  from  it,  behind 
the  transverse  fissure,  and  between  it  and  the  posterior  part 
of  the  umbilical,  is  another  lobe,  called  lobulus  Spigelii  or 
middle  lobe.  This  lobe  is  somewhat  pyramidal  in  its  shape, 
and  sends  over  the  transverse  fissure  a  projecting  papilla, 
which  is  one  of  the  porta  or  gateways  of  the  liver.  An 
elongation  of  the  lobulus  Spigelii,  outward  and  forward 
along  the  right  lobe  and  behind  the  transverse  fissure,  is 
called  the  lobulus  caudatus.  On  the  right  lobe  and  in  front 
of  the  transverse  fissure,  between  the  umbilical  fissure  and 
the  gall  bladder,  is  seen  another  elevation,  not  so  distinct, 
called  the  lobulus  quartus  or  anonymus.  Its  posterior  ex- 
tremity is  opposite  the  Spigelian,  and  constitutes  the  second 
port  a  of  the  liver.* 

*  The  author  had  an  opportunity  of  witnessing  a  very  curious  transposition  of 
parts  on  the  inferior  surface  of  a  liver  taken  from  a  subject  in  the  dissecting 
room  of  the  Baltimore  College  of  Dental  Surgery.  The  following  account  was 
sent  to  the  Medical  Examiner,  from  which  we  quote :  "I  am  sorry  to  say 
that  I  did  not  witness  the  removal  of  this  liver,  and  did  not  see  it  in  its  natural 
situation,  and  cannot  hence  state,  with  positive  certainty,  which  of  the  edges 


THE  LIVER.  679 

Structure  or  different  elements  of  the  Liver. — This  organ 
consists  of  membranes,  blood-vessels,  hepatic  ducts,  lymph* 
atics,  cellular  tissue,  nerves,  and  acini. 

The  membranes  are  the  serous,  which  has  been  noticed, 
and  the  fibrous.  This  latter  consists  of  condensed  cellular 
structure,  which  lies  beneath  the  serous  coat,,  and  forms  the 
immediate  covering  to  the  whole  surface  of  the  liver,  ad- 
hering to  it,  and  sending  innumerable  processes  every 
where  into  its  substance,  which  both  separate  and  surround 
the  different  granules  or  lobules,  forming  complete  capsules 
for  all  the  acini.  This  membrane  also  forms  a  sheath  for 
all  the  vessels  which  enter  or  depart  at  the  transverse 
fissure.  This  sheath  follows  and  continues  round  the 
ramifications  of  these  vessels  throughout  the  liver,  and 
takes  the  name  of  the  capsule  of  Glisson.  It  is  regarded  in 
fact  as  the  foundation  structure  of  all  the  different  elements 
composing  this  largest  gland  in  the  body. 

The  blood-vessels  of  the  liver  are  of  three  kinds,  two  of 
these  pass  in,  the  other  comes  out.  The  hepatic  artery  and 
vena  portarum  enter  the  liver,  while  the  vena  cava  hepat- 
ico3  pass  out. 

The  hepatic  artery  is  a  branch  of  the  coeliac  axis,  and  as- 

of  the  liver  presented  front  and  towards  the  ribs— a  fact  of  some  interest,  and 
in  reference  to  which  I  have  to  regret  my  not  being  able  to  procure  any  infor- 
mation from  those  who  removed  it. 

"  If  where  the  umbilical  vein  or  cord  enters,  be  taken  as  the  anterior  edge  of 
the  liver,  in  accordance  with  the  usual  anatomical  descriptions,  then  the  state 
of  things  is  as  follows  : 

"  1.  The  thickest  edge,  with  its  round  and  smooth  surface,  which  is  always 
described  as  posterior,  is  now  found  in  front,  while  the  anterior  sharp  edge  is 
placed  behind.  2.  The  right  lobe  is  much  the  smallest,  and  about  the  size  of 
what  the  left  usually  is,  while  the  left  was  the  usual  size  of  the  right.  3.  The 
lobulus  Spigelii  is  in  front,  instead  of  behind  the  transverse  fissure,  and  on  the 
left,  instead  of  the  right  lobe.  4.  The  inferior  vena  cava  was  also  in  front  of 
the  liver,  instead  of  its  back  part,  and  on  the  left  instead  of  the  right  lobe. 
If,  on  the  other  hand,  the  thick  and  round  edge  of  the  liver,  together  with  the 
usual  situation  of  the  lobulus  Spigelii  and  ascending  cava,  be  taken  as  the 
posterior  edge,  then  the  situation  of  the  parts  is  as  follows:  1.  The  gall 
bladder  is  on  the  posterior  edge  of  the  left  lobe,  instead  of  the  anterior  and 
inferior  surface  of  the  right.  2.  The  umbilical  cord  enters  the  centre  of  the 
posterior  edge,  instead  of  the  fissure  on  the  anterior  edge.  3.  The  lobulus 
Spigelii  passes  over  the  transverse  fissure  to  the  left  lobe." 


580 


THE  LIVER. 


cends  in  the  lesser  omenturn  to  the  transverse  fissure  of  the 
liver,  where  it  divides  commonly  into  three  branches,  one 
of  which  passes  to  the  right  lobe,  another  to  the  left,  and 
the  third  to  the  lohulus  Spigelii.  These  branches  follow 
the  ramifications  of  the  vena  portarum,  and  biliary  ducts, 
distributing  upon  each  a  complicated  tissue  of  anastomosing 
vessels,  ultimately  breaking  into  a  plexus  for  each  of  the 
acini.  This  artery  is  designed  to  nourish  the  liver. 

The  vena  port  arum  is  very  interesting  from  the  curious 
fact  of  its  having  an  origin  as  a  vein,  but  a  termination 

like  an  artery.  It  is  very  large, 
and  is  formed  by  a  junction  of 
the  splenic  and  mesenteric  veins, 
which  receive  the  blood  of  the 
stomach,  intestines,  spleen,  and 
pancreas,  forming  a  tube  from 
three  to  five  inches  in  length, 
which  is  seen  to  commence  be- 
hind the  pancreas,  in  front  of 
the  aorta,  and  to  ascend  ob- 
liquely upward  over  the  duode- 
num to  the  transverse  fissure  of 
the  liver,  where  it  divides  into 
two  branches,  at  right  angles 
with  the  vein,  called  the  sinus 
venaportarum.  These  branches 
are  right  and  left.  The  right  is 
the  largest,  but  shortest,  and  radiates  in  minute  branches 
to  the  right  lobe,  while  the  left  after  the  same  manner  is 
distributed  to  the  left  lobe  of  the  liver. 

This  vein  is  accompanied  by  the  hepatic  artery.  Both 
proceed  from  the  centre  to  the  circumference  of  the  liver, 
and  both  are  enclosed  in  canals  termed  portal  canals,  which 
are  formed  of  the  sheaths  or  processes  from  the  capsule 
of  Glisson.  Injection  shows  that  an  anastomosis  occurs 

FIG.  188  represents  the  Trunk  of  the  Vena  Porta  with  its  roots  and  branches 
in  the  intestines  and  liver,  a  a  Veins  from  the  intestines.  6  Trunk  of  vena 
porta.  c  c  Branches  distributed  in  the  liver. 


THE  LIVER.  581 

between  the  branches  of  the  portal  and  those  of  the  hepatic 
veins,  as  well  as  between  both  these  and  the  artery.  The 
capillary  terminations  of  the  vena  portarum  are  distributed 
upon  the  acini,  where  they  anastomose  freely  with  each 
other  and  with  the  hepatic  veins.  This  vein  furnishes  the 
blood  for  the  secretion  of  the  bile. 

The  venae,  cavce  hepaticce,  or  the  hepatic  veins,  commence 
in  the  acini,  from  the  capillary  terminations  of  the  hepatic 
artery  and  vena  portse,  which  successively  converge  into 
three  large  trunks,  greatly  exceeding,  in  size,  the  other 
vessels  of  the  liver.  Two  of  these  come  from  the  right  lobe, 
the  other  from  the  left,  and  enter  the  superior  cava,  just  as 
it  is  about  passing  through  the  diaphragm.  Just  below 
these  are  generally  seen  five  or  six,  and  sometimes  more, 
hepatic  veins,  which  return  the  blood  from  the  lobulus 
Spigelii  and  other  portions  of  the  liver. 

In  connection  with  these  vessels,  the  umbilical  vein  should 
be  mentioned.  This  vein  is  peculiar  to  the  foetus,  and  car- 
ries the  blood  from  the  placenta  of  the  mother,  through 
the  umbilical  opening  in  the  foetus,  to  the  transverse  fissure 
of  the  liver,  where  it  divides — one  branch  being  continuous 
with  the  vena  portse,  throughout  the  liver,  the  other  pro- 
ceeding backward,  in  the  posterior  part  of  the  umbilical 
fissure,  to  join  the  ascending  cava.  This  is  the  ductus  ve- 
nosus.  After  birth,  both  the  umbilical  vein  and  ductus 
venosus  are  obliterated  and  become  ligamentous  cords.  , 

The  hepatic  ducts  commence  in  the  acini  of  the  liver,  by 
very  fine  branches  termed  port  biliariij  which,  successively 
uniting,  finally  converge  to  the  transverse  fissure,  by  three 
or  four  trunks,  which  again  unite  into  a  single  tube  about 
an  inch  and  a  half  long,  called  the  hepatic  duct.  This 
unites,  at  an  acute  angle,  with  the  cystic  duct,  forming,  by 
their  union,  the  ductus  communis  choledochus.  This  com- 
mon duct  descends  from  the  liver,  behind  the  right  extrem- 
ity of  the  pancreas,  and  in  its  substance,  and  then  passes 
obliquely  through  the  coats  of  the  duodenum,  to  end  by  an 
orifice,  marked  by  a  papilla,  on  the  mucous  surface  of  this 
intestine,  at  the  posterior  part  of  its  second  curve. 


582  THE  LIVER. 

This  duct  is  to  the  right  of  the  artery,  having  the  vena 
portaa  behind  and  between  the  two.  It  has  two  coats — the 
internal  is  mucous,  and  the  external  fibrous.  The  use  of 
the  biliary  ducts  is  to  convey  the  bile,  after  its  secretion  in 
the  liver,  to  either  the  duodenum  or  the  gall  bladder. 

The  lymphatics  are  numerous  and  arranged  into  a  super- 
ficial and  deep  set.  The  former  are  seen  beneath  the  peri- 
toneum, in  the  form  of  a  net-work.  The  latter  pass  out 
of  the  liver,  at  its  transverse  fissure,  and  go  to  the  adjacent 
lymphatic  glands,  or  enter  the  thoracic  duct. 

The  nerves  come  from  the  solar  plexus,  and  accompany 
the  blood-vessels  into  the  liver.  Some  filaments  are  traced 
from  the  pneumogastric  and  phrenic. 

The  Acini. — This  element  is  best  seen  by  tearing  the 
liver,  when  it  presents  the  form  of  granules,  about  the  size 
of  millet  seed,  which,  from  their  resemblance  to  the  seed  of 
the  grape,  were  called,  by  Malpighi,  acini.  Their  shape  is 
described  as  spheroidal,  or  polyhedral,  and  each  one  is  con- 
sidered a  perfect  miniature  of  the  entire  gland,  as  each  is 
composed  of  the  capillary  blood-vessels  of  the  liver,  with 
commencing  radicles  of  the  excretory  ducts  or  pori  biliarii. 

MICROSCOPIC  ANATOMY  OP   THE   LIVER. 

The  observations  of  Mr.  Kiernan  are  generally  received 
as  the  most  accurate,  though  their  entire  correctness  has 
been  called  in  question  by  some  of  the  most  respectable 
anatomists.  According  to  this  gentleman,  the  acini  of 
Malpighi  should  be  called  lobules,  as  they  contain  still 
smaller  granules,  which  he  calls  the  proper  acini,  and 
which  present  two  colors — a  brown  and  a  yellow,  termed 
the  cortical  and  medullary  portions. 

This  distinction,  however,  is  now  pretty  generally  aban- 
doned, the  structures  being  regarded  the  same,  and  the 
difference  in  colors  being  considered  as  due  to  the  higher 
vascularity  of  the  brown,  and  the  presence  of  bile  in  the 
origins  of  the  pori  biliarii  of  the  yellow. 

The  lobules  present  a  rounded  form  with  angular  pro- 
jections. Each  has  a  base  which  rests  upon  a  hepatic  vein, 


THE  LIVER.  583 

the  sub-lobular,  (Fig  189,  B.)    The  base  enters  into  the 

constitution  of  the  walls  of  the  sub-lobular  vein,  and  the 

A  FIG.  189.  B  remainder 

of  the  lobule 
has  its  sur- 
face covered 
with  the  cap- 
sule  of  Glis- 
son,  in  which 

the  minute  branches  of  the  vena  portae,  hepatic  vein,  and 
hepatic  duct  ramify. 

The  interior  of  the  lobule  has  its  centre  (Fig.  189,  A) 
occupied  by  a  vein,  called  intra-lobular^  which  connects  it 
with  the  sub-lobular  vein.  The  intervals,  between  the  fis- 
sures of  adjacent  lobules,  are  called  interlobular  fissures  ; 
and  the  spaces,  formed  by  the  apposition  of  several  lobules, 
are  called  interlobular  spaces.  These  spaces  and  fissures 
are,  occupied  by  the  delicate  branches  of  the  portal  vein, 
hepatic  artery  and  duct,  termed  each  interlobular,  and 
formed  from  the  plexuses  belonging  to  the  sheaths,  consti- 
tuting the  portal  canals,  which  are  hence  called  vaginal 
plexuses.  From  the  interlobular,  branches  of  each  set  pro- 
ceed, and  enter  the  lobules,  forming  plexuses  in  each,  called 
lobular  venous }  and  lobular  biliary  plexuses. 

The  lobular  plexus  of  the  portal  vein  contains,  in  its 
meshes,  the  acini,  or  biliary  plexus,  and  is  traced  into  the 
intra-lobular  vein,  and  thence  to  the  sub-lobular,  from 
which  the  hepatic  veins  are  formed.  It  is  not  settled 
whether  the  terminations  of  the  biliary  ducts  are  coecal,  or 
anastomosing  arches. 

The  lobules,  thus  constituted,  are  supposed  to  be  nothing 
but  a  congeries  of  biliary  ducts,  surrounded  by  blood-ves- 
sels. More  recent  observations,  with  the  microscope,  make 
each  acinus  to  consist  of  a  collection  of  cells  of  various  size 

FIG.  189,  A  represents  the  Lobules  of  Mr.  Kiernan.  a  Intra-lobular  vein. 
b  Interlobular  fissure,  c  Interlobular  space. 

FIG.  189,  B  represents  the  Sub-lobular  vein,  a  Lobule,  b  Intra-lobular 
rein,  c  Sub-lobular  hepatic  vein — a  longitudinal  section  being  made  of  it. 


584 


THE  LIVER. 


and  shape,  containing  bile  with  globules  of  fat;  thus  prov- 
ing, it  is  thought,  that  these  cells  are  the  real  secreting 

agents  of  the  bile, 
and  that  from  these 
cells  it  is  conveyed 
into  the  pori  biliarii 
by  a  process  not  yet 
settled.  The  liver 
is  developed  by  a 
protrusion  from  the 
intestinal  canal. 

The  gall-bladder 
(Fig.  187)  is  situ- 
ated in  a  depres- 
sion upon  the  an- 
terior part  of  the 
lower  surface  of  the 
right  lobe  of  the 
liver,  and  is  a  reser- 
voir for  receiving 
the  bile.  Its  form 
is  conical;  its  larger 
portion,  or  fundus, 
projects  somewhat 
5  beyond  the  anterior 
edge  of  the  liver, 
and  looks  to  the 
right,  downward 
and  forward.  Its 
narrow  or  constrict- 
ed portion,  called  the  neck,  is  directed  upward  and  baek- 

FIG.  190,  A  represents  a  horizontal  section  of  three  Lohules,  displaying  the 
two  principal  systems  of  Blood-vessels.  Ill  Interlobular  veins  in  the  spaces. 
222  Interlobular  veins  in  the  fissures.  333  Lobular  venous  plexus.  444 
Jntralobalar  branches  of  hepatic  veins. 

FIG.  190,  B  represents  the  Lobular  Biliary  Plexus.  1  Two  lobules.  222 
Interlobular  ducts.  333  Interlobular  cellular  tissue.  4  4  Lobular  biliary 
plexus  injected.  5  5  Intra-lobular  branches  of  hepatic  vein.  6  6  Central  por- 
tions of  lobules  uninjected. 


ff 


THE  LIVER.  585 

ward  to  the  left,  where  it  becomes  somewhat  convoluted, 
and  ends  in  a  tube,  called  the  cystic  duct,  about  an  inch 
and  a  half  long,  which  has  already  been  described  as  join- 
ing the  hepatic,  to  form  the  ductus  communis  choledochus , 
whose  entrance  into  the  duodenum  has  already  been  traced. 

The  gall-bladder  has  three  coats.  The  first,  or  perito- 
neal, is  partial,  covering  only  the  anterior  surface;  the 
second  consists  of  condensed  cellular  structure,  and  is  called 
the  fibrous ;  while  the  third,  which  is  internal,  is  the  mu- 
cous coat.  This  coat  presents  wrinkles  or  folds  which  take 
a  tortuous  or  spiral  course,  and  have  between  them  nu- 
merous cells,  which  give  the  surface  of  this  coat  a  honey- 
comb appearance.  This  coat  is  always  found  colored,  either 
yellow  or  green,  from  the  bile. 

Blood-vessels. — The  artery  of  the  gall-bladder,  the  cystic, 
comes  from  the  hepatic.  Its  vein  goes  to  the  vena  portae. 
Its  nerves  come  from  the  sympathetic.  Its  lymphatics 
are  numerous,  and  unite  with  those  of  the  liver.  The  gall- 
bladder is  developed  by  an  offset  from  the  hepatic  duct. 

function  of  the  Liver. — The  office  of  this  viscus  is  clearly 
to  secrete  the  bile,  which  secretion  is  found  to  occur  in  the 
lobules  or  acini,  from  the  blood  of  the  portal  vein. 

The  bile  is  a  viscid  fluid,  of  a  yellow  or  greenish  yellow 
color,  and  a  very  bitter  taste.  It  is  said  to  consist  of  chole- 
sterine,  which  is  a  white,  fatty,  crystallizable  substance,  re- 
sembling spermaceti;  choleic  acid,  which  is  a  peculiar 
animal  substance  combined  with  soda ;  and  coloring  matter 
called  biliverdin.  The  chemical  analysis  of  Berzelius  makes 
bile  to  consist  of  water,  80  parts ;  bilin,  a  substance  taking 
the  resinous  condition  by  the  application  of  an  acid,  8  parts ; 
mucus,  3  parts ;  saline  substances,  of  which  soda  is  the 
prominent,  9  parts. 

The  offices  of  the  bile  are,  first,  to  act  upon  the  chyme  in 
the  duodenum,  in. its  conversion  into  chyle;  second,  a  por- 
tion of  it  unites  with  the  residuum  of  the  chyle,  and  is  passed 
off  by  the  bowels  as  excrement,  thus  ridding  the  blood  of 
its  superfluous  hydro-carbon ;  third,  it  excites  the  peri- 
staltic action  of  the  muscular  coat,  and  acts  as  a  stimulus  to 


586  THE  PANCREAS. 

increased  secretion  from  the  mucous  follicles ;  and  fourth, 
the  liver  is  regarded  as  the  only  organ  for  depurating  the 
blood  of  its  superfluous  hydro-carbon,  in  the  foetal  state  or 
before  respiration  is  established.*  , 

THE  PANCREAS,    (rtaj  2p£a$,   all  flesh.) 

This  gland  is  next  in  importance  to  the  liver,  from  the 
assistance  it  renders  in  completing  the  digestive  process, 
the  formation  of  the  chyle. 

It  is  situated  in  the  posterior  epigastric  region,  behind  the 
FIG.  191.  stomach,  and  in  front  of 

the  spine,  the  lesser  mus- 
cle of  the  diaphragm,  the 
„.  aorta,  ascending  vena 
cava,  and  superior  mes- 
enteric  artery,  and  be- 
tween the  two  laminae  of  the  mesocolon.  Its  direction  is 
across  the  body,  transversely  from  the  spleen  on  the  left, 
with  which  it  is  connected,  to  the  curvature  of  the  duode- 

FIG.  191  represents  the  Pancreas.  1  Head  of  the  pancreas.  2  Neck.  3 
Body.  4  Tail.  5  Pancreatic  duct. 

*  In  addition  to  these  functions,  M.  Bernard  adds  those  of  "  sanguification  and 
equilibrium."  His  recent  experiments  seem  to  show  that  the  Liver  forms 
sugar,  fibrin,  and  fat ;  that  these  three  substances  contribute  to  establish  the 
equilibrium  in  the  blood,  and  that  no  matter  what  the  aliment  is,  the  liver  has 
the  power  to  transform  it  into  material  fit  for  nutrition.  Thus  the  composition 
of  the  blood  is  preserved  in  its  proportionate  number  of  regular,  healthy  ele- 
ments; for  the  sugar,  fibrin,  and  fat,  being  thus  furnished,  restore  to  the  blood 
again  those  substances  which  it  is  continually  losing,  and  thus  preserve  the 
blood  in  a  state  of  health.  In  a  chemical  point  of  view,  the  liver  is  considered 
an  organ  of  sanguification. 

But  the  liver  is  also  regarded  as  regulating  the  equilibrium  of  the  circula- 
tion. Thus,  in  carniverous  animals  there  is  less  fat  secreted  by  this  organ, 
because  there  is  more  taken,  already  formed,  as  aliment.  In  the  herbiverous 
class,  where  there  is  much  saccharine  matter  consumed,  the  liver  forms  less 
sugar ;  and  the  less  fibrin  the  stomach  digests,  the  more  it  is  found  the 
liver  contains.  Consequently  in  man,  whose  diet  is  so  variable,  the  blood  will 
be  furnished,  by  the  liver,  with  that  element  in  the  largest  proportion,  which  is 
found  most  deficient  in  his  aliment,  thus  making  this  organ  a  balancing  organ, 
or  organ  of  equilibrium.  From  American  Journal  Medical  Sciences,  October, 
1851. 


THE  PANCREAS.  58*7 

num  on  the  right,  (Fig.  180,)  where  it  is  closely  attached, 
and  from  which  it  is  often  with  difficulty  separated.  Its 
form  is  somewhat  of  a  parallelogram,  about  seven  inches  in 
length,  and  two  in  breadth.  Its  color  is  of  a  light  gray,  or 
pink.  Its  structure  resembles  that  of  the  salivary  glands,  so 
much  so  that  it  is  called  the  abdominal  salivary  gland.  It 
belongs  to  the  conglomerate  class  of  glands,  and  consists  of 
lobules  of  various  size,  which  are  resolvable  into  still  smaller 
bodies  or  granules,  all  of  which  are  connected  by  cellular  tis- 
sue, with  their  interstices  occupied  by  blood-vessels.  This 
gland  has  no  proper  peritoneal  coat,  nor  investing  tunic, 
unless  the  lamina  of  condensed  cellular  membrane  which 
surrounds  it,  be  considered  as  such. 

Its  arteries  come  from  the  splenic,  which  courses  the  upper 
margin.  Its  veins  enter  the  splenic,  and  thence  the  vena 
portas.  Its  nerves  are  from  the  solar  plexus. 

Its  excretory  duct,  called  the  ductus  Wirsungii,  is  seen  by 
scraping  off  some  of  the  surface  of  the  gland  about  its  cen- 
tre, and  is  traced  as  a  remarkably  white  and  thin  tube, 
extending  from  the  left  extremity  or  tail  of  the  gland,  to 
its  right  or  head.  Here  it  increases  in  size,  and  is  some- 
times joined  by  a  duct  from  the  lesser  pancreas,  which  is  only 
an  enlargement  of  the  head.  This  duct,  just  before  entering 
the  duodenum,  joins  the  ductus  communis,  though  it  is  not 
unfrequently  seen  to  enter  separately.  It  arises  by  fine 
radicles  from  the  granular  masses,  constituting  the  lobules, 
like  the  vesicular  origins  of  the  salivary  glands.  These 
unite  to  form  the  still  larger  tubes  which  proceed  from  the 
circumference  to  the  centre,  and  discharge  nearly  at  right 
angles  into  the  common  duct. 

Function. — To  secrete  the  pancreatic  fluid,  which,  as 
stated  elsewhere,  is  conveyed  into  the  duodenum ;  with  the 
bile,  by  their  combined  agency,  it  converts  the  chyme  into 
chyle.  But  what  part  this  fluid  takes,  or  what  is  its  special 
action  in  the  process  of  chylification,  all  works  on  anatomy 
and  physiology  tell  us  is  yet  unknown.  This  uncertainty 
or  obscurity  as  to  the  use  of  the  pancreatic  fluid,  would 
seem  to  be  entirely  removed,  and  the  question  conclusively 


588  THE  PANCREAS. 

settled,  by  the  recent  experiments  of  M.  Bernard.*  The 
following  is  given  by  Prof.  March  as  the  substance  of  those 
experiments,  at  which  he  was  present :  "  Pancreatic  juice, 
when  collected  from  a  living  animal  (a  dog  for  example) 
by  means  of  a  fistula  artificially  established,  has  clearly 
identically  the  same  physical  character  as  the  saliva,  being 
limpid,  colorless,  slightly  ropy,  and  rather  heavier  than 
water.  It  is  constantly  alkaline,  and  is  coagulable  by  heat 
and  strong  acids,  owing  to  the  presence  of  albumen.  The 
saliva  is  slightly  alkaline  when  collected  pure,  but  never 
coagulable  by  heat  or  acids.  When  the  pancreatic  juice  is 
put  in  contact  with  azotised  aliments,  as  fibrin,  albumen, 
and  gelatine,  there  is  no  effect  produced.  Putrefaction  oc- 
curs in  time,  but  no  digestion.  When  applied  to  farina- 
ceous substances,  they  are  changed  into  sugar,  which  is  ab- 
sorbable."  Thus  far,  he  states,  is  known.  But  it  was  not 
known  before  the  discovery  of  M.  Bernard,  "  that  when  this 
fluid,  the  pancreatic,  is  put  in  contact  with  fatty  substances 
of  every  nature,  as  oils,  animal  fats,  butter,  &c.,  they  are 
quickly  digested  or  decomposed,  and  reduced  to  a  state  in 
which  they  may  be  absorbed  into  the  circulation.  This 
property  is  peculiar  to  the  pancreatic  juice,  not  being  pos- 
sessed by  the  saliva,  gastric  juice,  bile,  serum,  nor  any  other 
fluid  of  the  animal  economy.  The  first  effect  produced 
when  you  put  the  pancreatic  fluid  in  contact  with  the  oil, 
or  any  fatty  substance,  is  to  form  an  intimate  emulsion, 
which  will  not  separate  on  standing.  If  you  agitate  oil 
with  saliva,  gastric  juice,  serum  or  pure  bile,  or  any  other 
animal  fluid,  the  mixture  separates  when  in  repose."f 

The  great  office  of  the  pancreatic  fluid  then,  in  changing 
the  chyme  into  chyle,  seems  to  be  to  dissolve  and  hold  in 
solution  its  fatty  matters,  that  they  may  be  capable  of 
absorption.  M.  Bernard  also  states,  as  an  established  fact, 

*The  facts  stated  above  are  taken  from  the  first  number,  Vol.  1st,  of  the 
"  Ohio  Medical  and  Surgical  Journal,"  for  September,  1848. 

f  Frerichs  contradicts  Bernard's  statements  on  this  point,  but  he  has  manifestly 
misunderstood  them.  The  result  of  the  experiments  made  by  him,  Bidder, 
Schmidt  and  Lenz,  has  been  rather  a  modification  than  a  refutation  of  his 
views.  For  a  brief  account  of  these  results,  see  "  Dental  Chemistry,"  p.  144. 


THE  SPLEEN.  589 

"  that  the  union  of  the  bile  and  pancreatic  fluid  produces  a 
new  and  distinct  fluid,  having,  in  addition  to  the  peculiar 
properties  of  these  two  fluids,  another  superadded,  that  of 
digesting  azotised  substances,  or,  in  other  words,  having  the 
properties  of  the  gastric  juice." 

THE  SPLEEN,    (orttyv,  lien.) 

The  spleen  (Fig.  180)  is  situated  in  the  posterior  part  of 
the  left  hypochondriac  region,  having  the  diaphragm  above, 
and  the  colon  and  kidney  below,  and  the  stomach  and  pan- 
creas upon  its  right.  Its  shape  resembles  an  oval,  cut  in 
the  long  direction.  Its  color  varies,  though  most  generally 
it  is  a  deep  blue  or  purple.  Its  size  also  varies,  being  from 
four  to  five  inches  long,  and  from  two  to  three  inches  wide. 
It  is  convex  towards  the  ribs,  and  concave  towards  the 
stomach.  In  this  concavity  there  is  a  depression  called 
hilum  lienis,  in  which  the  blood-vessels  and  nerves  enter  and 
pass  out.  Sometimes  there  are  several  spleens,  in  which 
case  the  superfluous  ones  are  said  to  be  not  larger  than  nut- 
megs. 

Structure. — This  organ  (Fig.  192)  has  two  coats,  serous 
and.  fibrous.     The  serous  is  a  reflection  from  the  peritoneum, 
FIG.  192.       an(^  gives  it  a  complete  investment,  except 
where  the  vessels  enter.     This  coat  attaches 
the  spleen  to  several  organs,  as  the  stomach, 
colon,  and  diaphragm,  by  its  reflections,  called 
gastro-splenicj  splenico-colic}  and  splenico-plire- 
nic  ligaments. 

The  fibrous  or  proper  coat  is  closely  con- 
nected with  the  serous,  and  is  a  thin,  but 
compact,  extensible,  and  elastic  membrane, 
which  not  only  surrounds  this  organ,  but  sends  down  into 
its  substance  innumerable  fibres  and  lamellae,  which  traverse 
it  in  every  direction,  and  divide  it  into  partitions,  making 
it  cellular.  This  coat  also  forms  sheaths  for  the  blood- 

FIG.  192  represents  the  Spleen.  Between  1  and  2,  hilus  or  fissure  of  the 
spleen,  where  the  blood-vessels  enter  and  pass  out.  4  One  of  the  larger 
branches  of  the  splenic  artery.  5  Splenic  vein. 


590  ABSORBENTS  OF  THE  TRUNK. 

vessels  in  their  distribution  through  this  organ.  The  cells 
are  filled  with  a  bloody  pulp,  of  a  grumous  character,  in 
which  the  microscope  detects  a  number  of  small  oval  corpus- 
cles, of  a  reddish  color,  and  about  the  size  of  the  red 
globules  of  blood.  The  spleen  contains  also  some  small 
bodies,  called  after  Malpighi,  which  are  described  as  being 
about  the  third  of  a  line  in  diameter,  and  consisting  of  con- 
voluted blood-vessels  and  lymphatics,  connected  by  elastic 
tissue,  and  resembling  minute  lymphatic  glands.  They  are 
said  to  contain  lymph  of  the  color  of  milk. 

Blood-vessels. — The  splenic  artery,  the  largest  branch  of 
the  cceliac,  takes  a  tortuous  course  along  the  superior  mar- 
gin of  the  pancreas,  and  enters  the  hilum  of  the  spleen  by 
five  or  six  branches,  which  ramify  minutely  throughout 
its  substance.  Injections  have  shown  that  the  different 
branches  do  not  anastomose,,  hence  each  branch  is  regarded 
as  having  an  independent  function,  and  the  spleen  as  con- 
sisting really  of  several  organs  like  the  conglomerate  glands. 
The  veins  are  numerous,  having  thin  coats,  and  presenting 
enlargements,  which  are  compared  to  the  corpus  cavernosum 
penis.  These  differ  from  the  arteries  by  anastomosing 
freely  with  each  other,  and  unite  to  form  the  splenic  vein,  a 
very  large  trunk,  which  is  one  of  the  principal  roots  of  the 
vena  porta3.  This  vein,  like  the  rest  of  the  portal  veins,  is 
without  valves. 

The  nerves  come  from  the  solar  plexus  and  accompany 
the  artery.  The  lymphatics  are  superficial  and  deep,  and 
go  to  glands  at  the  hilum. 

Function. — The  use  of  this  organ  is  unknown,  but,  not- 
withstanding this,  there  is  no  scarcity  of  speculations  about 
the  matter.  The  most  generally  received  theory  is,  that  it 
serves  as  a  reservoir  or  diverticulum,  when  the  abdominal 
organs  are  threatened  by  undue  congestion  of  the  portal 

system. 

SECTION   III. 

ORGANS  OF  ABSORPTION  OF  THE  TRUNK. 

The  organs  of  absorption  naturally  follow,  in  the  physi- 
ological arrangement,  those  of  digestion;  for  while  it  is 


ABSORBENTS  OF  THE  TRUNK.  591 

the  office  of  the  latter  to  convert  the  crude  aliment  into 
chyme  and  chyle,  it  is  the  business  of  a  portion  of  the  for- 
mer to  take  up  this  chyle,  thus  prepared  for  the  nutrition 
of  the  body,  and  introduce  it  into  the  circulation,  whence 
it  is  conducted,  along  with  the  blood,  to  the  lungs,  where 
it  receives  its  final  and  finishing  stroke  as  blood,  to  be  now 
taken  up,  by  the  organs  of  circulation,  and  distributed 
throughout  the  system  for  the  support  of  every  part. 

The  organs  of  absorption  comprise  three  sets  of  struc- 
tures— the  lactealSj  lymphatics,  and  lymphatic  or  absorbent 
glands. 

Under  the  head  of  glandular  tissue,  some  general  re- 
marks are  made  upon  the  absorbent  system.  The  lacteals 
(Fig.  182)  and  lymphatics  are  regarded  as  parts  essentially 
of  the  same  system  of  vessels,  though  having  different 
names.  The  structure  of  both  is  the  same,  consisting  each 
of  two  coats — an  external,  which  is  regarded  as  fibrous  by 
some,  and  muscular  by  others ;  and  an  internal,  which  is 
very  delicate  and  transparent,  resembling  that  of  the  veins. 
A  middle  coat  is  also  spoken  of,  which  is  thin,  as  in  the 
veins,  but  destitute  of  the  elastic  lamina.  Like  the  veins, 
the  internal  coat  of  the  absorbents  presents  numerous  folds 
constituting  valves.  These  valves  are  of  semilunar  shape, 
and  arranged  in  pairs,  giving  the  vessels  containing  them 
a  braided  or  knotted  appearance,  (Fig.  18.)  These  valves 
prevent  the  retrograding  of  the  chyle  and  lymph.  The 
absorbents,  like  the  veins,  are  divided  into  the  superficial 
and  deep,  and  have  their  fluids  running  the  same  direction. 

The  trunks  of  the  absorbents  terminate  in  the  venous 
system;  hence  these  two  are  only  regarded  by  some 
as  continuations  of  one  and  the  same  system.  This 
difference  however  is  observed,  that  all  the  absorbents, 
whether  superficial  or  deep,  converge  and  pass  through  a 
set  of  bodies  called  lymphatic  or  absorbent  glands,  while 
veins  do  not.  The  absorbents,  on  entering  these  glands,  are 
termed  vasa  inferentia,  and  on  passing  out  vasa  efferentia. 
These  glands,  as  elsewhere  stated,  are  very  numerous,  pre- 
senting a  reddish,  or  gray  color,  varying  in  size  from  a  cur- 


592  LYMPHATICS  OF  THE  STOMACH. 

rant  to  an  almond,  and  mostly  of  an  oval  or  round  form. 
Their  consistence  is  firm,  each  being  surrounded  with  a 
fibrous  capsule.  They  generally  run  in  chains  or  clusters. 

The  division  of  the  absorbents  into  lacteals  and  lymphat- 
ics, is  founded  on  the  color  of  the  respective  fluids  ;  the  chyle 
of  the  lacteals  resembling  milk,  while  the  lymph  of  the  ab- 
sorbents looks  like  serum  or  water. 

The  lacteals  are  limited  to  the  abdomen,  and  have  their 
origin  in  the  numerous  villi  of  the  small  intestine,  espe- 
cially its  upper  portion,-  which  converge  to  the  mesenteric 
glands,  through  which  they  pass,  and  thence  proceed,  after 
being  reduced  to  one  or  more  trunks,  along  the  superior 
mesenteric  artery  to  its  root,  where  they  enter  the  thoracic 
duct.  The  mesenteric  glands  are  situated  between  the  lam- 
inse  of  the  mesentery,  and  are  estimated  at  about  one  or  two 
hundred  in  number. 

The  lymphatics  are  found  in  every  part  of  the  body,  ex- 
cept the  interior  of  the  brain,  spinal  cord,  cartilages,  ten- 
dons, and  ligaments,  and  though  they  are  not  as  yet 
demonstrable  in  these  parts,  there  is,  nevertheless,  the 
strongest  reason,  from  analogy,  for  believing  that  they 
exist  there.  Their  function  is  to  absorb  from  every  tissue 
all  the  particles  of  matter  that  have  become  effete,,  useless, 
and  as  it  were,  worn  out,  and.  to  conduct  these  into  the 
thoracic  duct,  there  to  mingle  with  the  chyle  from  the  lac- 
teals, and  thence  into  the  circulation,  or  as  in  the  right 
head  and  neck,  and  right  upper  extremity,  to  go  more  di- 
rectly into  the  venous  system.  The  lymph  then,  like  the 
chyle,  is  carried  into  the  venous  circulation,  is  mingled 
with  the  venous  blood,  and  conducted  to  the  lungs,  where 
the  purification  and  conversion  into  arterial  blood  occurs, 
so  that  it  is  fitted  to  enter  the  system,  and  perform  the 
same  office  of  nutrition  as  before. 

THE  LYMPHATICS  AND   GLANDS  OF  THE  STOMACH. 

The  lymphatics  of  the  stomach  are  superficial  and  deep . 
The  former  present  a  plexiform  arrangement  beneath  the 
peritoneum ;  the  latter,  a  similar  appearance  in  the  mucous 


LYMPHATICS  OF  THE  INTESTINES.  593 

coat,  converging  from  different  directions,  thus  accompany 
the  epiploic  and  coronary  vessels  to  the  glands,  along  the 
greater  and  lesser  curvature  of  the  stomach,  amounting  to 
eight  or  ten  in  number,  through  which  they  pass,  and 
thence  proceed  to  the  thoracic  duct.  Some  are  seen  going 
to  the  glands  of  the  spleen,  and  others  to  those  about  the 
pylorus. 

LYMPHATICS  AND   GLANDS  OF  THE  INTESTINES. 

The  lymphatics  of  the  small  intestine,  like  those  of  the 
stomach,  are  superficial  and  deep,  the  former  being  situated 
beneath  the  peritoneum,  the  deep  in  the  mucous  coat,  or 
between  the  latter  and  the  muscular.  Both  sets  enter  the 
mesenteric  glands,  and  go,  as  stated,  to  the  thoracic  duct. 

The  lymphatics  of  the  large  intestine  are  not  so  numerous 
as  those  of  the  small.  They  have  a  like  division  into  super- 
ficial and  deep,  and  also  follow  the  course  of  the  blood-ves- 
sels. Those  of  the  ascending  and  transverse  colon  unite 
with  the  lymphatics  of  the  mesentery;  while  those  of  the 
descending  colon  and  sigmoid  flexure  enter  the  lumbar 
glands.  The  lymphatics  of  the  rectum  do  not  all  go  to 
the  lumbar  glands — part  of  them  enter  the  hypogastric. 
The  lumbar  glands  are  very  numerous,  and  found  along  the 
course  of  the  common  iliac  arteries,  continuous  with  the 
pelvic  chain,  also  around  the  aorta,  ascending  cava,  on  each 
side  of  the  bodies  of  the  lumbar  vertebrae,  and,  in  fact, 
scattered  in  every  direction  from  the  base  of  the  sacrum  to 
the  diaphragm.  These  glands  not  only  give  passage  to 
the  lymphatics  of  the  left  portion  of  the  large  intestine, 
but  they  also' receive  all  those  of  the  pelvis,  corresponding 
to  its  several  viscera,  which,  after  passing  through  the  iliac, 
sacral,  and  lumbar  glands,  finally  enter  the  receptaculum 
chyli,  by  several  large  trunks  which  form  the  commence- 
ment of  the  thoracic  duct. 

LYMPHATICS  AND   GLANDS  OF  THE  LIVER. 

The  lymphatic  vessels  of  the  liver  are  superficial  and 
deep,  and  exceedingly  numerous.     They  are  readily  in- 
38 


594  LYMPHATICS  OF  THE  CHEST. 

jected  from  any  of  the  large  trunks,  by  the  yielding  of 
the  valves.  The  superficial  set  are  found  all  over  the 
convex  and  concave  surfaces  of  the  liver,  pursuing  dif- 
ferent directions.  On  the  convex  surface  some  are  seen 
to  enter'  the  suspensory  ligament  and  pass  through  the 
diaphragm  to  the  glands  in  the  anterior  mediastinum; 
others  go  to  the  horizontal,  thence  to  the  transverse  fissure, 
and  on  to  the  glands  of  the  omentum  minus  and  pylorus ; 
while  others  are  seen  to  accompany  the  vena  cava  into  the 
chest,  and  enter  the  thoracic  duct.  On  the  concave  surface 
of  the  liver  they  are  equally  numerous,  some  passing  to 
the  lesser  omentum,  and  others  to  the  superior  lumbar  and 
inferior  intercostal  glands.  A  distinct  plexus  is  seen 
around  the  gall-bladder. 

The  deep  lymphatics  of  the  liver  take  the  course  of  the 
portal  vessels  and  biliary  ducts,  and  pass  to  the  glands  of 
the  lesser  omentum,  and  thence  back  to  the  spine  to  enter 
the  thoracic  duct.  The  lymphatic  glands  of  the  liver  are 
found  along  the  hepatic  vessels,  and  continuous  with  those 
on  the  coeliac  artery. 

The  Lymphatics  of  the  Pancreas  and  Spleen  pass  to  the 
glands  along  the  splenic  artery,  and  finally  terminate  in 
the  thoracic  duct. 

The  lymphatics  of  the  abdominal  parietes  follow  the  course 
of  the  epigastric,  ilio-lumbar,  circumflexa  ilii,  and  lumbar 
arteries,  and  go  to  the  iliac  and  lumbar  glands.  Those  of 
the  diaphragm  join  the  intercostal  and  internal  mammary, 

THE  LYMPHATICS  AND  GLANDS  OF  THE  CHEST. 

The  lymphatics  of  the  chest  are  divided  into  the  parietal 
and  visceral.  The  former  pursue  the  course  of  the  thoracic, 
internal  mammary,  and  intercostal  vessels,  and  go  to  the 
axillary,  inferior  cervical,  and  intercostal  glands. 

The  visceral  lymphatics  belong  to  the  lungs,  the  heart, 
and  thymus  gland. 

Those  of  the  lungs  are  superficial  and  deep.  The  former 
are  spread  as  a  net-work  over  the  pulmonary  surface  be- 
neath the  pleura,  and  proceed  to  the  root  of  the  lungs  to 


LYMPHATICS  OF  THE  CHEST.  595 

enter  the  bronchial  glands.  The  deep-seated  take  the 
course  of  the  bronchial  vessels  and  tubes,  and  also  go 
to  the  bronchial  glands,  and  the  thoracic  duct,  and 
some  to  the  right  lymphatic  duct  at  the  base  of  the 
neck. 

The  lymphatics  of  the  heart  accompany  the  coronary  ves- 
sels and  proceed  to  the  bronchial  glands,  and  thence  to 
the  left  thoracic  duct. 

The  lymphatics  of  the  thymus  gland,  go  to  the  bronchial 
glands ;  and  those  of  the  oesophagus,  which  are  found 
to  be  very  numerous,  so  much  so  as  to  form  a  continued 
plexus  around  its  whole  extent,  also  enter  the  bronchial 
glands. 

The  lymphatic  glands  of  the  chest  are  also  parietal  and 
visceral.  The  former  are  found  near  the  heads  of  the  ribs, 
between  the  intercostal  spaces,  posterior  to  the  sternum, 
along  the  internal  mammary  vessels,  a  few  in  the  anterior 
mediastinum  reaching  from  the  diaphragm  to  the  neck, 
and  a  chain  of  them  along  the  oesophagus  and  aorta  in  the 
posterior  mediastinum. 

The  visceral  glands  are  the  bronchial  or  pulmonary, 
which  are  situated  about  the  root  of  the  trachea  at  its  di- 
vision, and  pursue  the  course  of  the  bronchia  for  some  dis- 
tance into  the  structure  of  the  lungs.  They  are  numerous 
and  large,  and  are  estimated  at  from  ten  to  twenty  in 
number.  Their  most  striking  peculiarity  is  their  color, 
which  is  black,  and  is  stated  to  depend  upon  a  deposition 
of  carbon  from  the  bronchial  lymphatic  vessels.  In  early 
life  these  glands  are  of  a  reddish  color,  then  gray,  and 
finally  black. 

The  left  or  great  thoracic  duct,  which  is  the  common  tube 
for  the  lymphatics  of  all  the  viscera  and  structures  below 
the  diaphragm,  as  well  as  those  of  the  left  side  of  the 
chest,  left  neck,  head,  and  left  upper  extremity,  commences 
below  the  diaphragm  in  the  receptaculum  chyli,  passes  up 
the  chest  between  the  aorta  and  vena  azygos,  and  finally 
terminates  at  the  junction  of  the  left  subclavian  and  inter- 
nal jugular  veins.  Its  course  is  more  fully  described  under 
the  head  of  glandular  tissue. 


ORGANS  OF  THE  CHEST. 

The  right  lymphatic  duct  receives  the  lymphatics  of  the 
right  side  of  the  chest,  right  lung,  right  diaphragm,  right 
upper  extremity,  right  neck,  and  head,  is  about  an  inch  in 
length,  and  enters  the  angle  formed  by  the  junction  of  the 
right  subclavian  and  internal  jugular  veins. 

This  is  the  most  common  disposition  of  the  two  thoracic 
ducts,  but  there  occasionally  occur  varieties  in  their  origin, 
course,  and  termination. 


CHAPTER  IV. 

THE  ^ORGANS  OF  THE  TRUNK. 

THIRD     DIVISION. 
ORGANS  OF  THE  CHEST. 

IN  the  physiological  order  these  organs  are  divided  into 
the  organs  of  respiration,  and  the  organs  of  circulation. 

GENERAL  OBSERVATIONS  ON  THE  CHEST. 

The  cavity  of  the  chest  or  thorax  occupies  an  inter- 
mediate situation  and  size,  in  comparison  with  the  other 
two  great  cavities  of  the  trunk,  the  cranial  and  abdom- 
inal, and  intermediate  also  in  relation  to  the  structure  of 
its  walls;  for  while  those  of  the  abdomen  consist  in  great 
measure  of  soft  parts,  and  those  of  the  head  of  a  hard  and 
complete  bony  case,  the  walls  of  the  thorax,  on  the  other 
hand,  combine  the  properties  of  both,  in  consisting  of  hard 
and  soft  parts  in  nearly  equal  proportions,  and  thus  har- 
moniously blending  the  fixed  and  dilatable  conditions  of 
each. 

Some  general  remarks  have  already  been  made  under  the 
head  of  passive  organs  of  the  trunk,  where  it  was  stated 
that  the  thoracic  cavity  presented  the  form  of  a  truncated 
cone,  with  the  apex  above  and  base  below,  flattened  before 
and  behind,  and  convex  at  the  sides;  that  its  form  and 
diameters  are  liable  to  variation  both  from  disease  and 


MUSCLES  OF  THE  CHEST.  597 

mechanical  appliances,  and  that  its  appearance  is  very 
different  when  viewed  after  having  the  upper  extremities 
detached.  In  this  condition,  with  the  arms  removed,  the 
chest  looks  larger,  as  it  really  is,  below  than  above,  while 
in  the  living  state,  or  with  the  bony  shoulder  and  arms  ap- 
pended to  the  skeleton,  this  cavity  looks  larger  above  than 
below,  which  it  is  not.  The  chest  is  bounded,  as  stated,  by 
the  sternum  and  costal  cartilages  in  front,  by  the  dorsal 
vertebrae  behind,  the  diaphragm  below,  the  ribs  and  the  in- 
tercostal muscles  laterally,  and  the  superior  opening  of  this 
cavity,  which  is  occupied  by  the  passage  through  it  of  the 
trachea,  oesophagus,  muscles,  vessels,  nerves,  and  cellular 
tissue,  above.  It  is  also  lined  by  a  serous  membrane,  which 
is  reflected  from  its  interior  walls  over  the  lungs  and  peri- 
cardium, called  the  pleura.  All  these  parts  have  been  de- 
scribed elsewhere,  except  the  muscles  on  the  anterior  walls 
of  the  chest  and  pleura,  which  we  shall  now  proceed  to 
notice. 

SECTION    I. 

MUSCLES  OF   THE  CHEST. 

Dissection. — Make  an  incision  through  the  integuments 
from  the  upper  edge  of  the  sternum  along  the  median  line  to 
the  xiphoid  cartilage.  From  the  upper  end  of  this  incision 
carry  a  second  along  the  clavicle  to  the  acromion  process, 
and  from  its  lower  end  a  third  along  the  lower  margin  of 
the  great  pectoral  muscle,  which  is  readily  seen,  to  the 
humerus.  Kaise  the  integuments  by  commencing  the  dis- 
section along  and  in  the  direction  of  the  third  incision  for 
the  right  side,  and  from  the  second  incision  for  the  left 
side.  This  will  be  exposing  the  great  pectoral  muscle  in 
the  direction  of  its  fibres.  A  superficial  fascia  will  be 
raised  at  the  same  time  with  the  integuments,  which  is 
both  delicate  and  cellular,  and  continuous  above  with  the 
superficial  fascia  upon  the  neck,  and  below  with  the  same 
upon  the  abdomen. 

The  Pectoralis  Major  (Fig.  167)  arises  fleshy  from  th 
anterior  two-thirds  of  the  clavicle,  tendinous  from  the  an- 


598  MUSCLES  OF  THE   CHEST. 

terior  surface  of  the  sternum,  the  whole  length  of  its  two 
upper  bones,  meeting  its  fellow  tendon  of  the  opposite  side 
along  the  median  line,  where  they  decussate,  and  thus 
cover  the  sternum  with  a  kind  of  aponeurosis.  We  have, 
however,  several  times  seen  the  sternal  origin  of  this 
muscle  entirely  fleshy,  and  meeting  its  fellow  in  the 
same  way  along  the  median  line.  It  also  has  a  fleshy 
origin  from  the  fifth  and  sixth  ribs,  sometimes  also  from 
the  third  and  fourth,  and  a  slip,  sometimes  fleshy  and 
sometimes  aponeurotic,  is  seen  to  connect  the  lower  portion 
of  the  costal  portion  with  the  upper  tendon  of  the  external 
oblique  or  rectus  muscle.  From  these  several  origins  the 
fibres  pursue  different  directions,  the  clavicular  descend,  the 
sternal  run  horizontally,  and  the  costal  ascend — the  whole 
uniting  into  one  broad,  thin  tendon,  which  is  inserted  into 
the  anterior  edge  of  the  bicipital  groove.  At  the  axilla 
the  muscle  is  folded  inward,  presenting  a  thick,  rounded 
margin,  and  at  its  insertion  the  clavicular  portion  is  seen 
to  descend  lower  than  the  sternal,  thus  producing  a  decus- 
sation  of  its  tendinous  fibres. 

Function. — To  draw  the  arm  inward  and  forward  upon 
the  chest.  If  the  arms  be  fixed,  this  muscle  can  elevate 
the  ribs,  and  thus  aid  in  inspiration.  If  the  arm  be  raised, 
the  costal  portion  can  draw  it  down  ;  and  by  the  action  of 
both  muscles  the  arms  are  folded  upon  the  chest. 

The  Pectoralis  Minor  (Fig.  167)  is  triangular  in  shape, 
and  seen  by  raising  the  last  from  its  origin,  and  turning 
it  over  towards  the  humerus.  It  arises  by  thin  tendin- 
ous digitations  from  the  third,  fourth,  and  fifth  ribs  at 
their  superior  margins,  proceeds  obliquely  upward  and 
outward,  and  is  inserted  by  a  short,  flat  tendon  into  the 
inner  face  of  the  coracoid  process  of  the  scapula. 

Function. — To  draw  the  shoulder  inward,  downward,  t'nd 
forward,  and  to  assist  the  great  pectoral  in  inspiration,  by 
raising  the  ribs,  when  the  scapula  and  arm  are  fixed. 

Serratus  Major  Anticus,  called  also  Serratus  Magnus,  (Fig- 
193.) — This  muscle  is  distinctly  brought  to  view  by  raising 
both  pectoral  muscles,  detaching  the  clavicle  from  thester- 


MUSCLES  OF  THE  CHEST. 


599 


FIG.  193. 


num,  and  throwing  the  whole  back  towards  the  spine.  It 
will  then  be  seen  as  a  thin,  broad  muscle,  covering  the  sides 
of  the  chest,  and  situated  between  the  ribs  and  the 
scapula. 

It  arises  from  the  eight  or  nine  upper  ribs,  by  as  many 
fleshy  digitations.  The  five  lower  interlock  with  the  ex- 
ternal oblique  muscle,  the  upper  one  is  short,  thick,  some- 
what square,  and  is  thought  to  resemble  a  distinct  mus- 
cle. Its  fibres  converge 
and  are  inserted  into  th 
whole  base  of  the  scap- 
ula. 

Function. — To  draw 
the  shoulder  forward, 
and  when  the  scapula 
is  fixed  it  can  draw  the 
ribs  outward,  and  aid 
in  inspiration. 

The  intercostales  (Fig. 
193)  occupy  the  spaces 
between  the  ribs,  are 
twenty-two  in  number, 
and  divided  into  an  ex- 
ternal and  internal  set. 
The  external  arise  from 
the  transverse  processes 
of  the  dorsal  vertebras,  and  from  the  inferior  acute  edge 
of  each  rib,  and  then  proceeding  downward  and  for- 
ward in  fasciculi,  are  inserted  into  the  superior  smooth 
border  of  the  rib  below  to  within  a  short  distance  of 
the  costal  cartilage,  the  intervening  space  to  the  sternum 

FIG.  193  represents  the  Serratus  Major  Anticus  Muscle.  1  Anterior  portion 
of  cervical  vertebrae.  2  Transverse  process  of  the  second  cervical  vertebra. 
3  6  Scalenus  anticus.  4  Levator  anguli  scapulae.  5  Lower  edge  of  serratus 
magnus.  7  Scalenus  medius.  8  First  rib.  9  Coraco-clavicular  ligaments. 
11  Clavicle.  12  Base  of  scapula,  where  the  subscapularis  is  attached.  13 
Upper  portion  of  serratus  magnus.  14  Lower  portion  of  subscapularis.  15  15 
Origin  of  serratus  major  anticus.  16  Internal  intercostal  muscles.  17  Ex- 
ternal intercostals. 


600  MUSCLES  OP  THE  CHEST. 

being  filled  by  aponeurosis.  The  internal  arise  from  the 
sternum  and  inferior  margin  of  each  cartilage  and  rib, 
descend  backward,  decussating  the  external,  and  are  in- 
serted into  the  superior  margin  of  the  cartilage  and  rib 
below,  as  far  back  as  the  angles  of  the  ribs.  These  two 
sets  are  separated  by  the  intercostal  vessels  and  nerves. 

Function. — To  raise  the  ribs,  and  enlarge  the  chest  in 
inspiration,  the  first  rib  being  first  fixed  by  the  scaleni. 

The  subclavius  arises  tendinous  from  the  cartilage  of  the 
first  rib,  forms  a  small  round  muscle,  situated  immediately 
beneath  the  clavicle,  and  is  inserted  into  the  exterior 
half  of  this  bone,  as  far  back  as  the  ligament  connecting 
the  coracoid  process  and  clavicle. 

Function. — To  draw  the  clavicle  and  shoulder  down- 
ward. 

The  triangularis  sterni  arises  from  the  posterior  surface 
and  edge  of  the  ensiform  cartilage  and  lower  part  of  the 
sternum.  Its  fibres  run  obliquely  outward  and  upward, 
to  be  inserted  by  fleshy  and  tendinous  digitations  into  the 
cartilages  of  the  third,  fourth,  fifth,  and  sixth,  and  some- 
times as  high  as  the  second  rib. 

Function. — To  draw  the  ribs  down  and  aid  in  expiration. 

Situated  upon  the  anterior  lateral  regions  of  the  chest 
are  the  two  mammce  or  breasts.  These  are  glandular  or- 
gans, and  belong  to  the  conglomerate  order.  They  rest 
upon  the  great  pectoral  muscles,  and  between  the  third 
and  seventh  ribs.  The  skin  over  the  breast  is  thin,  smooth, 
and  soft,  and  in  the  virgin,  of  a  rather  pale,  inclined  to  a 
bluish  tint.  In  those  who  have  borne  children,  and  are  ad- 
vanced in  life,  the  skin  loses  its  smoothness  and  becomes 
wrinkled,  more  uneven,  and  of  a  darker  color.  About  the 
centre  of  the  gland  the  nipple  is  seen,  which  may  be  either 
long  or  short,  sometimes  so  short  that  with  difficulty  the 
child  takes  hold  of  it.  It  consists  of  the  lactiferous  or  milk 
ducts  connected  by  cellular  tissue.  It  presents  the  form  of 
a  cone  in  the  virgin,  while  it  has  a  flattened,  cribriform 
appearance  in  one  giving  suck.  It  is  capable  of  erection, 
and  is  thought  by  some  to  have  the  erectile  tissue,  while 


MAMMARY  GLAND.  601 

others  think  it  does  not  possess  that  spongy,  cavernous 
character  of  the  true  erectile,  but  resembles  more  the 
dartoid  structure.  It  is  surrounded  by  an  areola,  which  is 
of  a  rose  color  in  the  virgin,  and  in  the  pregnant  or  lactat- 
ing  female  becomes  of  a  dark  brown.  Both  the  nipple  and 
areola  present  over  their  surface  numerous  small  tubercles, 
sebaceous  follicles,  and  nervous  papillae.  Each  tubercle 
presents  near  its  apex  three  or  more  foramina,  which  are 
the  openings  of  the  excretory  ducts  from  the  gland  com- 
posing the  tubercle,  and  whose  secretion,  it  is  believed,  is 
designed  to  protect  the  nipple  from  excoriation,  while  there 
are  some  who  regard  these  tubercles  as  lactescent.  Be- 
neath the  skin  and  front  surface  of  the  mamma  an  abund- 
ance of  cellular  tissue  intermixed  with  globules  of  fat  is 
seen,  which  makes  the  volume  of  the  gland  appear  much 
larger  than  it  really  is. 

Structure. — The  mammary  gland  is  surrounded  by  a  cap- 
sule of  cellular  membrane,  which  sends  down  processes 
into  its  substance,  separating  and  connecting  its  different 
parts.  It  consists  of  lobes  which  are  divided  into  lobules, 
and  these  again  into  granules,  about  the  size  of  millet 
seed,  which,  under  the  microscope,  are  found  to  contain 
vesicles.  (Fig.  I1?.)  The  lobules  give  the  exterior  surface  of 
the  gland  a  very  uneven  appearance,  from  being  separated 
at  different  depths,  by  irregular  fossae  which  are  filled  with 
adipose  and  cellular  tissue.  From  the  vesicles  of  the  sev- 
eral granules,  the  excretory  or  lactiferous  ducts  have  their 
origin.  The  ducts  as  well  as  the  granules  are  known  by 
their  white  color.  They  converge  from  all  parts  of  the 
gland  to  the  base  of  the  nipple ;  in  their  course,  dimin- 
ishing in  number,  but  increasing  in  size.  The  termination 
of  these  ducts,  at  the  base  of  the  nipple,  is  in  sinuses,  res- 
ervoirs, or  ampullae.  As  many  as  fifteen  of  these  sinuses 
are  enumerated,  having  different  diameters.  From  these 
about  twelve  or  twenty  ducts  pass  through  the  nipple  to 
its  extremity,  and  there  open  by  as  many  orifices.  These 
ducts  (Fig.  194)  are  lined  by  mucous  membrane,  and  when 
in  a  state  of  erection  are  doubled  or  folded  upon  them- 


602  THE  PLEUEA. 

selves,  thus  forming  valves  to  prevent  the  escape  of  the 
milk  when  not  needed.  These  ducts,  however,  have  no  true 
valves,  and  injection  shows  them  to  have  no  communication 
with  each  other. 

The  interior  of  the  mammary  gland,  when  a  section  is 
made,  presents  a  white,  fibrous  appearance,  in  which  the 
granular  arrangement  is  not  so  distinct,  unless  the  ex- 
amination, it  is  remarked,  be  made  during  lactation. 
The  arteries  supplying  this  gland  come  from  the  thora- 
FIG.  194.  cic,  the  intercostals,  and  inter- 

nal mammary.  The  veins  are 
superficial  and  deep — the  lat- 
ter accompanying  the  arteries. 
The  nerves  are  derived  from 
the  brachial  plexus  and  inter- 
costals. 

The  lymphatics  of  the  mammae 
are  numerous,  some  of  which  are 
traced  to  the  glands  of  the  ax- 
illa, others  pass  through  the  intercostal  spaces  into  the  an- 
terior mediastinum,  to  the  lymphatic  glands  in  this  situa- 
tion ;  while  others  accompany  the  intercostal  vessels  to  the 
posterior  mediastinum,  or  enter  directly  the  thoracic  duct. 
Function. — To  secrete  the  milk  designed  for  the  nourish- 
ment of  the  infant.  The  closest  sympathy  exists  between 
the  mammae  and  the  uterus. 

THE  PLEUEA,    (Fig.   195.) 

The  pleurae  form  the  interior  lining  and  complete  the 
walls  of  the  chest.  They  are  two  in  number  and  consist  of 
complete  sacs  without  any  opening,  and  are  reflected  from 
the  walls  upon  the  viscera  which  they  enclose.  The  organs, 
however,  are  all  on  the  outside  and  none  within  the  pleu- 
ral  cavity.  Each  pleura  is  one  continuous  membrane,  and 
can  be  traced  throughout  its  whole  extent.  That  portion 
covering  the  walls  is  called  pleura  parietalis  or  costalis, 
and  that  covering  the  lungs,  pleura  pulmonalis.  The 

FIG.  194  represents  the  Lactiferous  Ducts. 


THE  PLEURA. 


603 


FIG.  195. 


form  of  each  pleura  is  conical,  the  apex  being  above, 
and  their  relative  situation  has  been  compared  to  that 
of  two  bladders  placed  side  by  side,  so  as  to  leave  a  space 
between  them.  So  with  the  two  pleura,  they  are  situated 
upon  either  side  of  the  chest,  and  approach  each  other 
along  the  median  line,  having  a  space  between  them  called 
the  mediastinum.  This  space  is  divided  into  an  anterior, 
middle  and  posterior,  and  according  to  some,  also  a  superior 
mediastinum, 
each  of  which 
contains  dif- 
ferent organs. 
By  commen- 
cing on  the 
posterior  sur- 
face of  the 
sternum  with 
either  the 
right  or  left 
pleura,  we 
trace  this 
membrane  to 
the  front  of 

the  pericardium,  thence  back  to  the  anterior  root  of  the 
lungs.  From  the  root  it  is  reflected  over  the  anterior  sur- 
face of  the  lungs,  and  traced  round  upon  the  posterior  sur- 
face to  the  back  part  of  the  root,  whence  it  is  reflected 
to  the  posterior  pericardium,  and  back  to  the  sides  of  the 
vertebrae.  From  this  latter  point  the  pleura  stretches 
all  along  the  spine,  ascending  as  high  as  the  sixth  or 
seventh  cervical  vertebra,  and  as  low  as  the  diaphragm, 

Fie.  195  represents  the  Pleura  and  its  reflections  from  a  transverse  section 
of  the  chest,  a  Right  lung,  b  Left  lung,  c  Root  of  lungs,  showing  the  rela- 
tion of  its  vessels.  22  Pulmonary  vein.  1  Pulmonary  artery.  2  Bronchial 
tube,  d  d  Reflection  of  pleura  from  root  of  the  lung,  t  Cavity  of  pleura. 
/  Anterior  mediastinum,  g  Middle  mediastinum,  containing  the  heart,  h 
fcavity  of  the  pericardium-,  i  i  Direction  of  the  phrenic  nerves,  j  Aorta,  k 
Vena-azygos.  I  Thoracic  duct,  m  (Esophagus,  w  Sympathetic  nerve,  j  k  I 
are  in  the  posterior  mediastinum. 


604 


THE  MEDIASTINUM. 


completely  covering  this  latter  muscle,  and  expanding  out- 
ward from  the  spine  over  the  ribs  and  intercostal  muscles, 
forward  to  the  sternum,  where  the  sac  was  opened  and  the 
tracing  begun,  thus  showing  one  continuous  whole  through- 
out. It  is  thus  seen  that  each  pleura  forms  a  vertical  sep- 
tum from  the  sternum  in  front  to  the  spine  behind,  and 
that  the  space  between  these  almost  parallel  partitions  is, 
as  just  stated,  the  mediastinum. 

The  anterior  mediastinum  is  immediately  behind  the  ster- 
num and  in  front  of  the  pericardium.  Its  form  is  triangu- 
lar, the  base  being  the  sternum,  the  sides  are  formed  by  the 
two  pleura,  which,  approaching  each  other  very  closely  on 
the  top  of  the  pericardium,  constitute  the  apex.  It  con- 
tains much  fine  cellular  structure,  some  lymphatic  glands, 
and  at  the  superior  portion  the  origins  of  the  sterno-hyoid 
and  sterno-thyroid  muscles,  with  the  remains  of  the  thymus 
gland.  This  space  is  exposed  by  passing  up  one  or  two  of 
the  fingers  behind  the  sternum  from  the  abdomen,  so  as  to 
break  down  the  cellular  connections  between  the  pleurae, 
then  sawing  the  sternum  longitudinally  along  the  median 
line,  and  dividing  the  cartilages  near  the  sternum. 

The  middle  mediastinum  contains  the  pericardium  and 
heart,  ascending  aorta,  superior  vena  cava,  pulmonary  ar- 
teries and  veins,  and  division  of  the  trachea,  and  is,  as  its 
name  implies,  between  the  anterior  and  the  next  division. 

The  posterior  mediastinum,  directly  behind  the  middle, 
and  in  front  of  the  spine,  is  exposed  by  dividing  the  right 
pleura  in  a  longitudinal  direction  behind  the  root  of  the 
lung,  and  turning  the  latter  over  to  the  left  side,  when 
this  space  will  be  seen  to  contain  the  oesophagus  and  eighth 
pair  of  nerves,  the  descending  aorta,  vena  azygos,  thoracic 
duct,  splanchnic  nerves,  a  quantity  of  cellular  tissue,  and 
several  lymphatic  glands. 

A  reflection  of  the  pleura  from  the  root  of  the  lung  to 
the  diaphragm  is  called  ligamentum  latum  pulmonis. 

Structure. — The  pleura3  belong  to  the  class  of  serous 
membranes,  and  are  thin  and  transparent,  with  their 
internal  surface  smooth,  polished,  and  free.  Their  exter- 


THE  LUNGS.  605 

nal  surface  is  connected,  by  cellular  tissue,  to  the  ad- 
jacent parts,  having  varying  degrees  of  attachment,  being 
with  much  more  difficulty  separated  at  some  points  than 
others.  The  cellular  tissue  of  the  pleura  is  so  condensed 
as  to  take  the  form  of  a  fascia,  in  some  places,  as  on  the 
ribs,  where  it  is  strong  and  more  readily  detached  than  on 
the  diaphragm  or  lungs.  On  these  latter  it  is  so  thin  and 
delicate  as  scarcely  to  admit  of  demonstration ;  and,  though 
so  extremely  delicate  upon  the  lungs,  it  is  nevertheless 
asserted  to  be  strong,  resisting,  and  elastic,  and  that  this 
transparent  fascia  can  also  be  dissected  off  the  air-cells. 
The  pleura,  then,  is  really  a  fibro-serous  membrane,  and  in 
the  healthy  state  has  no  perceptible  blood-vessels. 

Function. — To  secrete  or  exhale  a  serous  fluid  upon  their 
internal  surface,  by  which  the  cavity  of  each  pleura  is  kept 
in  a  constantly  moist  and  lubricated  condition,  thus  allow- 
ing its  parietal  and  visceral  portions  to  glide  readily  upon 
each  other,  and  thereby  giving  both  the  lungs  and  walls 
of  the  chest  the  greatest  freedom  of  motion  during  respi- 
ration. 

SECTION   II. 

ORGANS  OF  RESPIRATION. 

These  comprise  the  larynx,  the  trachea,  bronchi,  and 
the  lungs. 

The  larynx  and  trachea  have  already  been  described  in 
another  place ;  we  therefore  proceed  to  examine  the  lungs. 

THE  LUNGS,    (PULMONES.) 

The  lungs  are  two  in  number,  right  and  left,  and  situ- 
ated upon  either  side  of  the  chest,  having  the  mediastinum 
and  heart  to  separate  them.  When  distended  with  air,  the 
pleura  pulmonalis  and  pleura  parietalis  are  in  close  juxta- 
position; and,  strictly  speaking,  there  cannot  be  said  to  be 
any  thoracic  cavity,  as  the  distended  lungs  fill  the  whole 
space,  excepting  the  small  part  occupied  by  the  heart  and 
thymus  gland. 


606  THE  LUNGS. 

The  form  of  the  lungs  is  conical,  the  apex  being  above, 
rounded,  and  seen  to  rise  from  one  to  two  inches  above 
the  level  of  the  first  rib ;  the  base  below,  and  concave,  to 
correspond  to  the  convex  surface  of  the  diaphragm.  The 
base  of  the  lung  presents,  from  before,  obliquely  downward 
and  backward,  precisely  in  the  direction  of  the  diaphragm, 
and  consequently  makes  the  vertical  extent  of  the  lungs 
behind,  which  reach  from  the  first  to  the  last  rib,  much 
greater  than  in  front,  where  the  extent  is  only  from  the 
first  rib  to  the  lower  end  of  the  second  bone  of  the  sternum. 

FIG.  196. 


l-L 


The  size  of  the  lungs  is  in  a  direct  ratio  with  the  capac- 
ity of  the  thorax.  The  average  volume  of  air  they  are 
capable  of  containing,  after  an  ordinary  inspiration,  is  esti- 
mated at  140  cubic  inches;  and  after  expiration,  at  110 
cubic  inches.  From  thirty  to  forty  cubic  inches  is  the 
average  estimate  of  air  inhaled  at  each  inspiration. 

The  specific  gravity  and  density  of  the  lungs  are  less  than 

FIG.  196  represents  the  Lungs,  their  anterior  surface,  with  the  Heart.  1  The 
heart — right  ventricle.  2  Pulmonary  artery.  3  Left  bronchus.  4  Vena  in- 
nominata— its  junction.  8  Right  auricle.  9  Pulmonary  vein.  11  Superior 
lobe  of  right  lung.  12  Middle  lobe.  13  Inferior  lobe.  14  Superior  lobe  of 
left  lung.  15  Inferior  lobe. 


THE  LUNGS.  607 

that  of  any  other  organ.  This  depends  on  the  presence  of 
the  air.  Their  absolute  weight  is  less  in  the  foetus  than 
after  birth.  In  the  former  the  proportion  to  the  body  is 
as  one  to  sixty ;  in  the  latter,  as  one  to  thirty. 

The  elasticity  of  the  lungs  is  very  considerable,  and  it  is 
by  this  property  they  are  aided  in  the  act  of  expiration. 
This  property  is  demonstrated  by  the  collapsing  of  the 
lungs  on  opening  the  chest.  Before  the  chest  is  opened, 
the  organs  are  not  collapsed,  as  the  air  they  contain, 
by  the  pressure  from  within,  keeps  them  constantly  dis- 
tended; but  when  the  chest  is  opened,  the  atmospheric 
pressure  from  without  balances  that  within,  and  then  the 
elasticity  has  the  opportunity  of  exerting  its  influence, 
and  produces  the  state  of  collapse. 

The  color  of  the  lungs  varies  according  to  the  age.  In 
the  foetus  it  is  found  to  be  of  a  reddish  brown,  after 
birth  of  a  light  rose  or  pinkish  hue ;  in  the  adult  it  is 
grayish,  interspersed  with  black,  which  presents  the  form 
either  of  lines,  patches,  or  points,  and  in  old  age  these 
black  deposits  increase. 

The  surfaces  of  the  lungs  are  external  and  internal.  The 
external  is  convex  and  corresponds  to  the  concavity  of  the 
rjbs,  presenting  a  variety  of  different  shaped  figures  sep- 
arated by  intermediate  dark  lines.  The  internal  is  con- 
cave for  receiving  the  pericardium  and  heart.  The  lungs 
are  divided  into  two  lobes  by  a  deep  fissure  commencing 
behind  and  below  the  apex,  and  descending  obliquely 
downward  and  forward  to  the  front  of  the  base.  Upon  the 
right  lung  there  is  another  fissure,  which  is  short,  and 
leads  from  the  middle  of  the  great  one  forward  to  the  an- 
terior margin,  thus  making  another  lobe  for  the  right 
lung,  which  is  in  the  middle,  to  the  other  two.  The  rela- 
tive position  of  the  two  lobes  is,  the  one  superior  and 
anterior,  the  other  inferior  and  posterior.  Sometimes  the 
left  lung  is  found  with  three  lobes,  and  the  right  with 
four  or  more. 

The  anterior  edge  is  short,  thin,  and  oblique.  The 
posterior  edge  is  long,  thick,  round,  and  vertical. 


608 


THE  LUNGS. 


The  interlobular  surfaces  formed  by  the  several  fissures 
entering  into  the  lungs,  are  all  free,  smooth,  and  covered 

Fig.  197. 


"by  pleura,  and  increase  to  an  immense  extent  the  area 
for  the  cells. 

Structure,  (Fig.  197.) — The  different  elements  constituting 
the  lungs  are  the  bronchial  tubes,  pulmonary  arteries,  pul- 
monary veins,  bronchial  arteries  and  veins,  lymphatic  vessels 
and  nerves,  all  connected  by  cellular  tissue  and  covered  by 
pleura.  These  several  tissues  before  entering  the  lungs 
are  all  collected  into  a  small  compass,  and  known  by  the 
name  of  the  root  of  the  lungs.  This  root  is  about  an  inch 

FIG.  197  represents  the  distribution  of  the  Bronchise  and  Blood-vessels,  with 
the  relation  of  the  Lungs  and  Heart.  1  Left  auricle.  2  Right  auricle.  3 
Left  ventricle.  4  Right  ventricle.  5  Pulmonary  artery.  6  Arch  of  aorta. 
7  Superior  vena  cava.  8  Arteria  innominata.  9  Left  carotid  artery.  10  Left 
subclavian.  11  Trachea.  12  Larynx.  13  Superior  lobe  of  right  lung.  14 
Superior  lobe  of  left  lung.  15  Right  pulmonary  artery.  16  Inferior  lobe  of 
the  lungs. 


THE  LUNGS.  609 

and  a  half  long,  half  an  inch  wide,  and  situated  upon  the 
internal  surface  of  the  lung,  a  little  above  its  centre.  It 
fixes  the  lung  on  either  side. 

The  bronchi,  or  air  tubes,  (Fig.  165,)  form  the  terminat- 
ing branches  of  the  trachea,  coming  off  about  opposite  the 
fourth  dorsal  vertebra,  and  consisting  of  the  right  and 
left  bronchus. 

The  right  passes  beneath  the  right  pulmonary  artery  to 
the  lung,  is  about  an  inch  long  before  dividing,  and  is 
larger  and  shorter  than  the  left. 

The  left  bronchus  is  about  an  inch  longer  than  the  right, 
though  smaller,  and  passes  through  the  arch  of  the  aorta 
obliquely  downward  to  the  left  lung. 

The  right  bronchus  is  embraced  at  the  root  of  the  lung 
by  the  vena  azygos ;  the  left  by  the  arch  of  the  aorta. 
The  right,  on  entering  the  lung,  divides  into  three  branches, 
the  left  into  two,  and  both  right  and  left  then  divide  and 
subdivide  into  an  almost  infinitude  of  branches  throughout 
the  lungs.  At  the  bifurcation  of  the  trachea  into  the 
bronchia,  there  is  observed  a  triangular  ligament,  strong 
and  elastic,  occupying  the  space  of  separation ;  and  after 
entering  the  lung,  the  primitive  divisions  of  each  bron- 
chus divide  into  two,  and  each  one  of  these  again  into 
two,  and  so  on  dichotomously  as  far  as  they  can  be  traced, 
the  fine  tubes  ultimately  terminating  in  the  lobules,  which 
latter  compose  the  air-cells,  and  these  again  consist  sim- 
ply of  the  dilated  terminations  of  the  extended  branch- 
ings of  the  bronchial  tubes  throughout  the  pulmonary 
structure. 

Each  bronchus,  in  its  primitive  division,  like  the  trachea, 
has  its  cartilaginous  rings  deficient  in  the  posterior  third. 
But  on  entering  the  lungs,  the  rings  form  smaller  seg- 
ments of  circles,  and  consist  of  small  pieces  placed  equally 
round  the  bronchial  tubes  so  as  to  constitute  them  cylin- 
ders. These  pieces  have  different  forms,  and  can  overlap 
and  glide  upon  each  other,  by  means  of  the  circular  mus- 
cular coat,  whose  fibres  are  connected  with  the  extremities 
and  margins  of  these  cartilages,  and  in  this  way  the  diam- 
39 


610  THE  LUNGS. 

eter  of  these  tubes  can  be  diminished,  and,  as  suggested  by 
Dr.  Physic,  the  expulsion  of  mucus  greatly  facilitated. 
These  bronchial  cartilages,  as  they  proceed,  become  smaller 
and  smaller  till  reduced  to  simple  lines,  patches,  or  grains, 
when  they  are  finally  lost  and  the  tube  becomes  wholly 
membranous. 

The  cartilages  of  the  bronchi  are  all  connected  by  a 
continuation  of  the  same  elastic  fibrous  tissue,  that  belongs 
to  the  rings  of  the  trachea.  The  extent  of  the  muscular 
coat  of  the  bronchi  is  not  exactly  determined ;  some  are 
disposed  to  think  it  ceases  at  the  last  bronchial  cartilage, 
while  others  carry  it  somewhat  beyond  this  point  upon  the 
membranous  portion  towards  the  cells.  The  mucous  mem- 
brane of  the  bronchi  is  a  continuation  of  the  same  that  lines 
the  trachea  and  larynx,  and  is  traced  on  into  the  air  cells 
of  the  lungs.  It  is  very  vascular,  and  is  seen  to  present  a 
number  of  longitudinal  folds.  This  membrane  abounds 
with  mucous  follicles,  whose  orifices,  upon  its  surface,  are 
so  numerous  as  to  present  »the  cribriform  appearance.  At 
the  beginning  of  the  bronchi  the  mucous  coat  is  found 
firm,  thick,  and  red.  As  it  proceeds  it  becomes  thinner 
and  paler,  till  in  the  membranous  terminations  it  appears 
transparent  and  of  great  tenuity. 

The  Air  Cells. — These  cells,  which  are,  as  just  stated, 
the  ultimate  coecal  terminations  of  the  bronchi,  form 
clusters  of  cells,  constituting  the  several  lobules.  Their 
precise  form  and  arrangement  still  remain  a  matter  of 
doubt,  for  while  on  the  one  hand  they  are  regarded  by 
Keisessen  and  his  followers  to  be  round,  and  related  to 
each  other  after  the  manner  of  the  fruit  on  a  bunch  of 
grapes,  each  grape  being  connected  by  a  separate  pedi- 
cle to  one  common  stock,  so  it  was  thought  that  the 
cells  of  the  lobules  had  no  communication  directly,  but 
only  by  their  ducts,  which  lead  to  a  common  bronchial 
tube  ;  Dr.  Horner's  experiments  seem  to  show  conclusively, 
on  the  other  hand,  that  the  cells  of  each  lobule  communi- 
cate directly  the  one  with  the  other,  but  not  with  the  cells 
of  different  lobules;  and  the  terminating  bronchial  branches, 


THE  LUNGS.  611 

which  he  remarks  are  about  the  size  of  a  bristle,  and  dis- 
tinctly seen,  are  supposed  to  have  somewhat  the  same  at- 
tachment to  the  lobule  and  its  cells  as  a  blow-pipe  fixed  to 
the  side  of  a  small  piece  of  sponge. 

The  diameter  of  these  cells  is  estimated  from  the  l-50th 
to  the  l-200th  of  an  inch,  and  they  have  no  regular  shape 
or  size.  By  a  calculation  18,000  of  them  are  made  to 
belong  to  each  lobule,  and  about  six  hundred  millions  to 
the  whole  lungs,  which  will  afford  some  idea  of  the  im- 
mensity of  surface  provided  for  the  reception  of  air,  and 
the  ample  facilities  for  purifying  the  blood  by  such  an 
arrangement. 

The  pulmonary  artery,  seemingly  the  next  element  in  im- 
portance, comes  from  the  right  ventricle  of  the  heart,  be- 
neath the  arch  of  the  aorta,  and  divides  into  two  branches. 
The  one  on  the  right  is  larger,  goes  to  the  root  of  the  right 
lung,  and  thence  divides  and  subdivides  throughout  the 
substance  of  this  viscus  into  capillary  branches,  which  are 
found  to  terminate  upon,  and  completely  surrounding  and 
lining  the  interior  of  the  air  cells.  The  left  pulmonary 
artery  has  the  same  distribution,  but  is  smaller  than  the 
right.  Both  these  arteries  convey  dark,  venous  blood  to 
the  air  cells  of  the  lungs,  where  this  impure  blood  is 
brought  in  contact  with  the  air,  and  the  change  from  dark 
venous  into  red  arterial  blood  occurs,  a  change  constituting 
the  great  leading  object  in  the  function  of  respiration. 

The  pulmonary  veins  commence  at  the  air  cells,  and  are 
formed  by  fine  radicles  from  the  ultimate  terminations  of 
the  pulmonary  artery.  These  all  successively  converge  into 
four  trunks,  two  for  the  right  and  two  for  the  left  lung, 
which  take  up  the  red  blood  formed  in  the  cells,  and  convey 
it  into  the  left  auricle  of  the  heart. 

The  bronchial  arteries  come  from  the  thoracic  aorta,  fol- 
low the  course  of  the  blood-vessels  above  mentioned,  ramify 
in  every  direction,  and  are  designed  for  the  nourishment  of 
the  lungs. 

The  bronchial  veins  return  the  venous  blood  into  the  vena 
azygos. 


612  THE  LUNGS. 

The  lymphatics  are  abundant  both  on  the  surface  and  in 
the  substance  of  the  lungs,  and  go  to  the  bronchial  glands. 

The  nerves  come  from  the  pneumogastric  and  sympa- 
thetic ;  chiefly  from  the  former.  A  plexus  exists  on  the 
front  and  back  of  the  roots  of  the  lungs,  called  the  anterior 
and  posterior  pulmonary  plexuses.  These  nervous  filaments 
are  traced  along  the  bronchial  tubes,  forming  anastomoses 
around  them,  and  are  supposed  to  expand  themselves  upon 
the  mucous  membrane  and  blood-vessels. 

All  these  different  elements,  constituting  what  is  termed 
the  parenchyma  of  the  lungs,  are  collected  and  run  together 
in  the  root,  at  which  point  their  relation  with  one  another 
is  as  follows :  after  the  pleura  is  removed  from  the  anterior 
part  of  the  root,  we  see  the  pulmonary  veins  below  but  in 
front  of  the  pulmonary  artery, — this  latter  being  above  and 
behind  the  veins, — while  the  bronchial  tube  is  above  and 
behind  the  artery. 

Function. — The  function  of  the  lungs  or  of  respiration,  is 
quite  a  complex  act.  This  act  consists  in  eliminating  car- 
bonic acid  from  the  blood,  and  supplying  its  place  with 
oxygen,  or,  in  other  words,  in  converting  venous  into  arte- 
rial blood.  To  accomplish  this  object,  a  variety  of  organs 
are  employed.  The  ribs  and  intercostal  muscles,  the  dia- 
phragm, the  scaleni,  the  great  and  superior  serrati  muscles, 
with  others,  all  concur  in  greater  or  less  degree  to  enlarge 
the  diameters  of  the  chest,  thereby  increasing  its  capacity 
for  the  reception  of  air,  and  thus  accomplishing  the  act  of 
inspiration.  The  abdominal  muscles,  and  the  posterior 
inferior  serrati,  aided  by  the  elasticity  of  the  cartilages, 
draw  down  the  ribs,  and  the  diaphragm  at  the  same  time 
ascending,  the  diameters  of  the  chest  are  diminished, 
thereby  expelling  the  air  from  the  lungs,  and  in  this  way 
accomplishing  the  second  act  of  respiration,  termed  ex- 
piration. 

The  pneumogastric,  intercostal,  phrenic  and  sympa- 
thetic nerves  are  essential  elements  in  putting  all  this 
machinery  in  motion,  as  well  as  in  maintaining  it  in 
action. 


THE  THYMUS  GLAND.  613 


THE  THYMUS  GLAND. 

This  body  is  noticed  here  from  being  located  in  the  vicin- 
ity of  the  thoracic  organs,  rather  than  from  any  thing  that 
is  especially  known  of  its  physiological  relationships. 

It  is  situated  in  the  anterior  mediastinum,  occupying  a 
greater  part  of  its  extent.  During  foetal  life,  and  for  the 
first  year  or  two  after  birth,  it  descends  in  front  of  the 
pericardium  nearly  as  low  as  the  diaphragm,  and  ascends 
upon  the  neck  as  high  as  the  thyroid  gland.  After  the 
second  year  it  commences  diminishing  till,  at  the  period  of 
puberty,  scarcely  a  vestige  of  it  remains.  Cases,  however, 
are  not  wanting  in  which  it  has  been  seen  at  from  20  to 
30  years,  even  larger  than  in  children,  and  even  from  30 
to  50  it  has  been  found  of  considerable  size.  This  body, 
though  called  a  gland,  is  destitute  of  one  of  the  great  char- 
acteristics of  a  gland  proper,  an  excretory  duct.  It  is  a  sym- 
metrical body,  consisting  of  two  lobes,  of  an  oblong  form, 
which  are  connected  as  well  as  separated  by  cellular  tissue. 

Structure. — The  lobes  of  the  thymus  are  divisible  into 
lobules,  which,  according  to  the  observations  of  Sir  Astley 
Cooper,  consist  of  vesicles  of  different  sizes  connected  by  cel- 
lular tissue,  which  also  forms  a  common  capsule  to  the  gland 
itself.  These  vesicles  or  cells  communicate  with  a  central 
cavity  or  reservoir,  which  contains  a  milky  fluid,  like  chyle. 
This  cavity  is  lined  by  a  vascular  mucous  membrane,  on  the 
surface  of  which  the  opening  cells  are  seen.  The  consist- 
ence of  this  gland  is  soft,  and  its  color  of  a  pinkish  hue. 

Its  arteries  come  from  the  superior  and  inferior*  thyroid, 
and  internal  mammary.  Its  veins  go  to  the  thyroid,  and 
vena  innominata.  The  lymphatics  join  the  absorbents  at 
their  junction  with  the  internal  jugular  and  subclavian 
veins.  The  nerves  are  derived  from  the  internal  mammary 
plexus  of  the  sympathetic. 

Function. — The  use  of  this  body  is  yet  unknown,  though 
its  great  importance  to  foetal  life  is  admitted  by  all.  Sir 
A.  Cooper  suggests  that  the  milk-like  fluid  found  in  its 
cavity  is  furnished  by  it  for  the  purpose  of  nourishing  the 


614  THE  HEART. 

foetus  before  birth,  as  well  as  for  a  short  time  after  birth 
till  chylification  is  fully  established. 

Another  opinion  entertained  is,  that  it  is  a  diverticulum 
of  blood  from  the  lungs  of  the  foetus,  when"  these  organs, 
as  before  birth,  are  known  to  be  inactive. 

SECTION   III. 
ORGANS    OF  CIRCULATION. 

These  organs  comprise  the  heart,  arteries,  and  veins, 
with  the  lymphatics,  which  are  regarded  as  appendages. 

Under  the  head  of  the  vascular  tissue  will  be  found  a 
general  description  of  the  different  systems  of  circulation ; 
and  under  the  head  of  organs  of  absorption  will  be  seen  an 
account  of  the  lymphatics.  All  that  we  propose,  therefore, 
in  this  place,  is  to  confine  our  remarks  to  the  heart,  and 
great  arterial  and  venous  trunks,  by  giving  somewhat 
more  in  detail  the  description  of  these  important  organs. 

THE   HEART — (Fig.    10.) 

The  heart,  styled  the  central  organ  of  the  circulation, 
is  a  hollow  muscle.  It  is  situated  (Fig.  196)  near  the  cen- 
tre of  the  thoracic  cavity,  in  the  middle  mediastinum, 
behind  the  sternum,  in  front  of  the  vertebral  column,  be- 
tween the  lungs,  and  above  the  diaphragm.  Its  form 
resembles  that  of  a  cone,  and  it  is  divided  into  a  base, 
body,  and  apex.  Its  direction  is  oblique,  from  above,  on 
the  right,  across  the  spine,  downward  and  forward  to  the 
costal  ends  of  the  fifth  and  sixth  cartilages,  on  the  left. 
Its  average  length,  from  apex  to  base,  is  estimated  at  about 
five  inches,  four  of  which  are  given  to  the  ventricles.  The 
base  is  about  four  inches. 

Its  weight  is  from  six  to  eight  ounces ;  though  all  these 
measurements  are  liable  to  considerable  variation  compat- 
ible with  health. 

The  heart  is  surrounded  and  kept  in  its  position  by  a 
fibro-serous  membrane,  called  the  pericardium.  This  mem- 
brane forms  a  conical  bag  for  receiving  the  heart,  and, 


THE  HEART.  615 

being  much  larger  than  this  organ,  allows  it  free  motion 
within  its  walls.  The  pericardium  consists  of  two  layers, 
an  external  or  fibrous,  and  an  internal  or  serous. 

The  fibrous  layer  is  attached  below  to  the  cordiform 
tendon  of  the  diaphragm,  to  which  it  is  strongly  bound  by 
compact  cellular  substance;  laterally  it  is  embraced  by 
the  two  pleuraB ;  in  front  it  corresponds  to  the  anterior, 
and  behind  to  the  posterior  mediastinum.  Above  it  is 
traced  upon  the  great  vessels,  proceeding  from  the  heart, 
upon  the  aorta  as  high  as  the  arch,  upon  the  pulmonary 
artery,  upon  the  superior  cava  for  an  inch  before  entering 
the  right  auricle,  upon  the  inferior  cava,  and  upon  the 
pulmonary  veins.  It  is  prolonged  upon  the  sheath  of  these 
vessels,  being  insensibly  lost  upon,  and  becoming  identified 
with  their  external  coat.  In  structure  it  is  like  the  dura 
mater,  though  thinner.  It  is  also  white,  inelastic,  and 
semi-transparent. 

The  internal  layer  of  the  pericardium  is  seen  by  opening 
this  bag,  when,  like  all  serous  membranes,  it  presents  a 
smooth,  polished,  delicate,  transparent  surface,  and  forms 
a  shut  sack.  It  lines  the  interior  of  the  fibrous  coat,  and 
is  reflected  thence  upon  the  great  vessels  to  the  heart, 
whence  it  is  traced  over  this  organ,  covering  its  anterior 
and  posterior  surfaces.  It  is  connected  to  the  heart  by 
cellular  substance,  having  frequently  interposed  a  quantity 
of  adipose  matter. 

Function. — The  pericardium,  by  its  fibrous  coat,  is  of  use 
in  fixing  and  retaining  the  heart  in  its  natural  position,  and 
preventing  over-distention  of  its  several  cavities;  while, 
by  its  serous  layer,  a  fluid  is  furnished,  which  both  lubri- 
cates and  facilitates  the  motions  of  this  organ. 

The  heart,  as  already  stated,  is  a  hollow  muscle,  and 
contains  four  cavities,  (Fig.  198,)  two  of  which  are  upon 
the  right  side,  and  anterior,  the  other  two  upon  the  left 
side,  and  posterior.  The  two  upon  the  right  being  sepa- 
rated by  partitions  from  those  on  the  left,  constitute  the 
heart  a  double  organ,  which  is  distinguished  into  a  right 
and  left  heart.  Two  of  these  cavities  occupy  the  superior 


616 


THE  HEART. 


part,  forming  the  base,  and  are  termed  auricles.  The  other 
two  occupy  the  middle  and  lower  portions,  constituting  the 
body  and  apex,  and  are  called  ventricles. 

198-  The  right  heart  is  com- 

posed of  the  right  auricle 
and  right  ventricle,  (Fig. 
199,)  the  left  heart  of  a  left 
auricle  and  left  ventricle, 
(Fig.  200.)  The  right  heart 
receives  venous  blood ;  the 
left,  arterial  blood. 

We  shall  examine  the 
heart  in  the  order  of  its 
circulation.  The  blood  en- 
ters first  the  right  auricle, 
by  the  superior  and  inferior 
vena  cava ;  from  this  cavity  it  passes  into  the  right  ventri- 
cle, through  the  ostium  venosum.  From  the  right  ventri- 
cle it  goes  to  the  lungs,  by  the  pulmonary  artery.  From 
the  lUngs  it  returns  to  the  left  heart  by  the  four  pulmonary 
veins,  entering  at  the  left  auricle.  From  the  left  auricle  it 
goes  through  the  ostium  arteriosum  into  the  left  ventricle ; 
and  from  the  left  ventricle  it  passes  out  by  the  aorta,  to  be 
distributed  to  all  parts  of  the  body. 

Eight  Auricle. — Make  an  incision  from  the  superior  to 
the  inferior  cava,  and  cross  it  by  another  running  trans- 
versely along  the  centre  of  the  cavity.  On  washing  out 
the  blood  there  is  seen,  at  the  upper  and  posterior  part, 
the  'superior  vena  cava,  descending  obliquely  forward  and 

FIG.  198  represents  the  Cavities  of  the  Heart,  a  Right  auricle,  b  Superior 
cava — its  entrance,  c  Inferior  cava — its  entrance,  d  Entrance  of  coronary 
vein,  partly  closed  by  valve,  e  Eustachian  valve.  /  Fossa  ovalis.  g  Tuber- 
culum  loweri.  h  Musculi  pectinati.  i  Right  auriculo-ventricular  opening, 
or  ostium  venosum.  j  Right  ventricle,  k  Tricuspid  valve.  I  Chordae-tendi- 
neae,  and  carneae  column®,  m  Pulmonary  artery — its  three  semi-lunar  valves, 
seen  at  its  commencement,  n  Right  pulmonary  artery,  o  Left  pulmonary 
artery,  p  Left  auricle,  q  Openings  of  the  four  pulmonary  veins,  r  Left 
auriculo-ventricular  opening,  or  ostium  arteriosum.  s  Left  ventricle,  t  Mi- 
tral valve,  it  Aorta — its  commencement  and  semi-lunar  valves,  v  Arch  of 
aorta. 


THE  HEART. 


61? 


inward,  about  an  inch  within  the  pericardium,  to  enter  the 
auricle.  There  is  no  valve  at  the  entrance  of  this  vein. 
At  the  lower  portion  of  the  auricle  the  inferior  cava  is 
seen  to  enter  FIG.  199. 

obliquely  hack- 
ward  and  in- 
ward, ascend- 
ing within  the 
pericardium 
onl y  for  a  short 
distance. 

At  the  en- 
trance of  this 
vein  there  is  a 
valve,  called 
the  valve  of 
Eus  tachius, 
which,  in  the 
adult,  is  very 
imperfect,  but 
in  the  foetus  is 
quite  large, 

and,  according  to  Sabatier,  is  obviously  designed  to  conduct 
the  foatal  blood  to  the  foramen  ovale,  and  prevent  the  mix- 
ing of  the  superior  and  inferior  ^streams.  This  valve  is 
formed  by  a  doubling  of  the  lining  membrane  of  the  auri- 
cle, surrounding  about  one  half  of  the  front  of  the  inferior 
cava,  and  stretching  between  this  vessel  and  the  fossa 
ovalis,  with  which  it  is  connected. 

Between  the  two  cava,  about  midway,  is  seen  a  transverse 
prominence,  called  tuberculum  Loiveri.  The  direction  of  the 
blood,  entering  the  auricle  by  these  two  veins,  is  such' 

FIG.  199  represents  the  right  Heart  laid  open.  4  Superior  cava.  8  Its 
entrance  into  right  auricle.  18  Inferior  cava — its  entrance  into  the  right 
auricle.  13  Smooth  portion  of  right  auricle.  14  Eustachian  valve.  15  mus- 
culi  pectinati.  9  Fossa  ovalis,  or  remains  of  foramen  ovale.  19  Annulus 
ovalis.  22  Opening  of  coronary  vein.  1  Cavity  in  right  ventricle,  leading  to 
the  pulmonary  artery.  11  Pulmonary  artery.  12  Septum  between  ventricles. 
3  Tricuspid  valve.  6  Aorta. 


618 


THE  HEART. 


says  Mr.  Wilson,  that  a  stream  forced  into  the  superior, 
takes  a  course  towards  the  ostium  venosum,  or  right  au- 
riculo-ventricular  opening — while  the  inferior  current  is 
directed  to  the  septum  auricularum,  or  fossa  ovalis,  the 
natural  course  of  the  blood  in  the  foetal  state.  The  outer 
and  posterior  walls  of  the  auricle  are  dilated  into  a  pouch 
called  its  sinus,  while  the  superior  projecting  extremity, 
with  indented  edges,  from  its  resemblance  to  the  ear  of  the 
dog,  gets  the  name  of  auricle. 

This  portion,  together  with  the  sinus,  has  a  number  of 
fasciculi  of  muscular  fibres  running  parallel  to  each  other, 
and  called,  from  their  resemblance  to  the  teeth  of  a  comb, 
musculi  pectinati.  Between  these  fasciculi  the  spaces  con- 
tain no  muscular  fibre. 

The  internal  wall  of  this  cavity  consists  of  a  thin  parti- 
tion called  the  septum  auricularum,  which  separates  it  from 
the  left  auricle.  On  the  lower  part  of  this  septum  a  de- 
pression is  seen,  the  fossa  ovalis,  the  margin  of  which  all 
round  is  thick  and  elevated,  and  termed  annulus  ovalis. 
This  fossa  ovalis  corresponds  to  the  opening  in  the  foetus 
called  foramen  ovale,  through  which  the  blood  passed  freely 
and  directly  from  the  right  auricle  to  the  left,  but  which, 
after  respiration  is  established,  becomes  closed  by  the  sep- 
tum just  mentioned. 

To  the  left  of  the  Eustachian  valve  is  seen  an  orifice 
about  the  size  of  the  common  quill ;  this  is  the  opening  of 
the  coronary  vein  of  the  heart,  and  is  protected  by  a  semi- 
lunar  valve  called  the  valve  of  Thebesius,  which  is  formed 
by  a  duplication  of  the  lining  membrane  of  the  auricle, 
and  prevents  the  blood  from  regurgitating  into  the  vein. 
At  different  points  of  the  auricle,  small  orifices  are  seen, 
called  foramina  TJiebesii,  some  of  which  are  regarded  as 
the  terminations  of  veins,  while  others  simply  lead  into 
the  muscular  depressions. 

Eight  Ventricle. — The  passage  from  the  right  auricle  into 
the  right  ventricle  is  through  a  large,  round  opening,  the 
ostium  venosum  or  right  auriculo-ventricular  opening.  A 
dense  white  line,  termed  the  right  tendon  of  the  heart, 


THE  HEART.  619 

surrounds  this  opening.  By  making  one  incision  along 
the  right  side  of  the  heart,  and  another  along  the  septum 
cordis,  and  turning  up  a  flap  from  below,  this  cavity  will 
be  exposed.  Its  form  is  triangular,  with  the  base  above 
and  connected  with  the  auricle,  while  its  lower  extremity 
stops  a  little  short  of  the  apex  of  the  heart.  The  right 
ventricle  occupies  the  anterior  and  right  side  of  the  heart, 
and  has  its  walls  much  thicker  than  those  of  the  auricle, 
being  estimated  about  three  lines,  while  the  latter  is  but 
one  line. 

Its  interior  surface  is  very  irregular  from  numerous 
muscular  fasciculi  called  columnce  carnece.  These  fleshy 
columns  are  differently  arranged  ;  some  are  connected 
along  their  whole  length  ;  others  are  fixed  by  their  ex- 
tremities ;  while  others  again  are  only  attached  by  one 
extremity,  having  the  other  free,  to  which  is  connected 
several  round,  tendinous  chords  called  chordae  tendinece. 
These  chords  interlace  among  themselves,  and  are,  with 
the  valve,  placed  between  the  right  ventricle  and  auricle. 
This  valve  is  formed  by  a  fold  of  the  lining  membrane 
projecting  from  the  auriculo-ventricular  opening,  and, 
from  being  divided  into  three  pieces,  is  called  tricuspid. 
One  of  these  pieces  is  posterior,  on  the  septum  cordis ;  a 
second  is  anterior  and  the  largest,  separating  the  auricu- 
lar from  the  pulmonary  arterial  orifice,  while  the  third  is 
to  the  right  side.  This  valve  prevents  the  blood,  during 
the  contraction  of  the  ventricle,  from  returning  back  into 
the  auricle,  which  is  done  by  the  columnar  carneae  con- 
tracting, and  putting  upon  the  stretch  the  chordae  tendineaa, 
which  draw  the  several  pieces  of  the  tricuspid  to  each 
other,  while  at  the  same  time  the  blood  gets  behind,  and 
thus  assists  to  approximate  as  well  as  support  them,  and 
prevent  their  being  forced  open. 

At  the  superior  and  left  extremity  of  the  right  ventricle, 
is  seen  the  orifice  of  the  pulmonary  artery.  This  orifice  is 
smooth  and  round,  about  an  inch  in  diameter,  and  protected 
by  three  valves,  termed  semilunar  or  sigmoid.  These  valves 
are  formed  by  a  duplication  of  the  lining  membrane  of  the 


620 


THE  HEART. 


artery,  being  connected  to  the  latter  by  their  circumference, 
and  having,  in  the  centre  of  each  loose  edge,  a  little  white 
or  yellowish  body  called  corpusculum  Arantii.  These  cor- 
puscles serve  as  abutments  to  support  each  other  when  the 
valves  are  brought  together,  and  thus  prevent  the  blood 
from  regurgitating.  Exterior  to  these  valves,  and  between 
them  and  the  artery,  are  three  pouches  called  the  sinuses  of 
Valsalva. 

The  pulmonary  artery  ascends  obliquely  backward  to 
the  under  part  of  the  arch  of  the  aorta,  where  it  divides 
into  two  branches,  one  for  each  lung.  The  right  is  both 
longer  and  larger ;  it  goes  behind  the  aorta  and  superior 
cava  to  the  root  of  the  right  lung,  where  it  divides  into 
three  branches.  The  left  is  shorter,  and  goes  in  front  of 
the  descending  aorta  to  the  root  of  the  left  lung  where  it 
divides  into  two  branches.  The  distribution  of  these 
branches  has  been  already  given  in  the  description  of  the 
lungs.  Where  the  pulmonary  artery  divides  into  its  right 
and  left  branches,  a  ligamentous  cord  is  seen  to  extend 
backward  and  downward  to  the  lower  extremity  of  the 
arch  of  the  aorta.  This,  in  the  foetus,  was  an  open  tube 
called  the  ductus  arteriosus,  through  which  passed  to  the 
aorta  the  balance  of  the  blood  which  failed  to  go  through 
the  foramen  ovale,  the  pulmonary  arteries  carrying  to  the 
lungs  only  so  much  as  was  just  sufficient  for  their  nutrition. 

Left  heart,  (Fig.  200,) — Left  auricle. — The  pulmonary 
veins,  four  in  number,  two  from  each  lung,  return  the  blood, 
after  it  has  been  changed  from  venous  into  arterial,  into 
the  left  auricle.  This  auricle  is  situated  at  the  superior 
and  back  part  of  the  base  of  the  heart,  being  hid  by  the 
ventricles  and  right  auricle.  Its  shape  is  more  of  a  square 
than  the  right,  and  it  has  a  pulmonary  vein  entering  each  of 
its  angles.  It  consists,  like  the  right,  of  a  sinus  and  appen- 
dix. Its  walls  are  thicker  and  stronger  than  those  of  the 
right  auricle,  though  its  cavity  is  smaller.  Its  appendix 
contains  ihemusculipectinati,  and  is  more  indented,  crooked 
and  narrower,  than  that  of  the  right.  At  the  inferior  part 
of  this  auricle  is  seen  the  opening  into  the  left  ventricle, 


THE  HEART. 


621 


called  ostium  arteriosum,   or   the  left  auriculo-ventricular 
opening. 

Left  ventricle. — This  cavity  presents  a  conical  form,  and  is 
posterior  to  the  right  ventricle.  Its  "base  is  above,  and  apex, 
which  is  below,  projects  be- 
yond the  right,  and  consti- 
tutes the  apex  of  the  heart. 
Its  walls  are  about  three 
times  as  thick  as  those  of 
the  right  ventricle,  and  it 
has  the  same  arrangement 
of  columnce  carnece  and  chor- 
dce  tendinece,  as  the  right, 
only  thicker  and  stronger. 

The  partition  between 
the  two  ventricles  is  styled 
the  septum  cordis.  It  con- 
sists of  a  thick  muscular 
wall,  formed  mostly  by  the 
left  ventricle.  At  the  upper  and  back  part  of  this  cavity 
the  left  auriculo-ventricular  opening  is  seen,  and  is  found  to 
be  protected  by  a  fold  of  the  lining  membrane  projecting 
from  round  the  margin  of  this  orifice  into  the  ventricle,  and 
dividing  into  two  portions,  called  the  mitral  valve.  The 
margin  of  this  opening  consists,  as  in  the  right,  of  a  white 
and  dense  tendinous  structure. 

The  anterior  division  of  the  mitral  valve  is  larger  and 
broader  than  the  posterior,  and  covers,  in  a  great  measure, 
the  aortic  opening.  This  valve,  as  well  as  the  tricuspid, 
contains  the  fibrous  structure,  is  attached  by  tendinous 
chords  to  the  columna?  earner,  and  serves  to  prevent  the 
reflux  of  blood  into  the  auricle. 

The  orifice  of  the  aorta  is  seen  in  front  of  the  auricular 
opening,  #nd,  like  that  of  the  pulmonary  artery,  is  guarded 

FIG.  200  represents  the  left  Ventricle  laid  open,  a  Parietes  of  left  ven- 
tricle. 6  Its  cavity,  c  Mitral  valve,  d  Chorda?  tendineae.  e  Columnse 
carneae.  /  Right  auricle,  g  Left  auricle,  h  h  Four  pulmonary  veins,  i 
Aorta .  j  Pulmonary  vein. 


622  THE  HEART. 

by  three  semilunar  valves,  having  the  same  provision  of 
corpuscula  Arantii  and  sinuses  of  Valsalva,  but  larger  and 
stronger,  and  having  a  similar  function  of  preventing  the 
reflux  of  the  blood.  The  capacity  of  the  different  cavities 
of  the  heart  is  very  nearly  the  same,  and  is  estimated  at 
about  two  ounces. 

Structure. — Several  elements  enter  into  the  composition 
of  the  heart.  There  is  first  and  most  external,  the  reflected 
serous  layer  of  the  pericardium,  covering  the  whole  of  the 
outer  surface,  and  already  described.  On  the  inner  surface, 
and  lining  the  auricles  and  ventricles,  is  seen  a  very  deli- 
cate and  transparent  serous  membrane,  called  the  endocar- 
dium. It  is  strongly  attached  to  the  muscular  fibres  of  the 
columnaa  carnese  and  musculi  pectinati,  filling  up  their  in- 
terstices, rendering  smooth  the  whole  interior  surface  of  the 
several  cavities,  and  by  its  duplications  forming  the  differ- 
ent valves  found  between  the  auricles  and  ventricles,  and 
at  the  mouths  of  the  aorta  and  pulmonary  artery. 

Between  the  outer  and  inner  membrane  is  situated  the 
muscular  structure.     This  is  the  most  abundant  and  im- 
FlG  201.  portant  element  of  the  heart. 

Its  fibres  are  difficult  to 
trace,  and  it  is  advised  to 
submit  them  to  boiling, 
maceration,  putrefaction, 
and  hardening  in  alcohol, 
as  some  of  the  necessary 
preparatory  means  to  a  suc- 
cessful dissection.  Accord- 
ing to  Cruveilhier,  this  ele- 
ment of  the  ventricles  "is 
composed  of  two  muscular 
sacs,  contained  within  a 
third,  which  is  common  to  both  ventricles/'  All-  the  mus- 

FIG.  201  represents  the  spiral  course  of  the  muscular  fibres  of  the  Heart, 
chiefly  those  of  the  left  ventricle.  1  Left  ventricle.  2  Right  ventricle.  3 
Septum  of  the  ventricles.  4  Muscular  fibres  making  a  spiral  turn  around.  5 
The  apex. 


THE  HEART.  623 

cular  fibres  are  traced  to  the  fibrous  zones  or  tendinous 
circles  of  Lower,  which  are  situated  at  the  auriculo-ventricu- 
lar,  and  arterial  orifices,  and  constitute  the  frame-work  of 
the  heart. 

These  fibres  are  divided  into  the  superficial  or  common, 
and  deep  or  reflected.  The  superficial  are  traced  from  the 
base  of  the  heart,  taking  a  spiral  course  to  the  apex — those 
on  the  anterior  portion  going  from  right  to  left,  and  those 
on  the  posterior  from  left  to  right,  meeting  and  decussating 
at  the  apex.  From  this  latter  point,  where  they  turn 
round  upon  themselves,  they  are  reflected  upward,  and 
constitute  the  deep  layers.  Those  belonging  to  the  ante- 
rior superficial  set  form,  by  their  reflection,  the  deep  layer 
of  the  posterior  wall,  while  those  of  the  posterior  superfi- 
cial set  constitute  the  deep  layer  of  the  anterior  wall.  Be- 
tween these  two  sets,  an  intermediate  one,  called  the  proper 
fibres  of  each  ventricle,  is  seen.  They  are  compared  to  a 
small  barrel  or  truncated  cone,  their  superior  openings 
corresponding  with  the  orifices  between  the  auricles  and 
ventricles,  while  their  inferior  are  observed  to  leave  two 
considerable  spaces,  which  are  simply  occupied  by  the  com- 
mon fibres.  This  accounts  for  the  apex  of  the  heart  being- 
weaker  than  any  other  portion  of  the  ventricles. 

The  muscular  fibres  of  the  auricles  are  also  divided  into 
a  superficial  and  deep  set.  The  former,  the  fibres  common 
to  both  auricles,  occupy  their  anterior  surface,  and  run 
transversely  from  right  to  left.  The  deep  set,  or  proper 
fibres  form  a  uniform  circular  layer.  Some  of  them  are 
also  oblique,  and  constitute  a  muscular  sphincter  round  the 
several  orifices  of  the  auricles.  The  muscular  layer  of  the 
right  auricle  is  not  so  uniform  and  continuous  as  that  of 
the  left.  The  septum  of  the  auricles  also  contains  muscu- 
lar fibres,  which  form  a  ring  round  the  fossa  ovalis.  At 
the  septum  of  the  ventricles,  the  right  and  left  hearts  are 
capable  of  separation,  if  carefully  done. 

The  arteries  of  the  heart  come  from  the  aorta,  and  are 
the  first  branches  given  off  at  its  origin.  They  are  the 
right  and  left  coronary. 


624  THE  HEART. 

The  right  coronary  artery  arises  above  the  anterior  semi- 
lunar  valve  in  front  of  the  aorta,  makes  its  appearance 
"between  the  right  auricle  and  ventricle,  and  following  the 
course  of  the  groove  between  these  two  to  the  posterior 
part,  distributes  branches  as  it  proceeds  to  the  right  auricle 
and  right  ventricle. 

The  left  coronary  artery  comes  from  above  the  left  semi- 
lunar  valve,  and,  while  concealed  by  the  pulmonary  artery, 
divides  into  two  branches,  a  superior  and  inferior.  The 
superior  passes  round  the  groove  between  the  left  auricle 
and  left  ventricle  to  the  back  of  the  heart,  and  supplies 
these  two  cavities  with  branches.  The  inferior  division 
descends  along  the  septum  of  the  ventricles  to  the  apex  of 
the  heart,  supplying  with  branches  both  ventricles,  and 
anastomosing  freely  with  the  other  coronary  branches. 

The  coronary  veins  return  the  blood  of  the  heart,  and 
are  distinguished  into  the  greater  and  lesser  coronary.  The 
greater  coronary  vein  begins  at  the  apex  of  the  heart,  by  the 
union  of  several  branches,  and  then  ascends  along  the  an- 
terior septum  of  the  ventricle,  to  terminate  finally  in  the 
right  auricle,  at  its  posterior  inferior  part,  to  the  left  of  the 
inferior  cava,  where  it  is  guarded  by  a  valve.  Throughout 
its  whole  course  it  is  constantly  receiving  streams. 

The  lesser  coronary  vein  returns  the  blood,  mostly  of  the 
right  ventricle,  and  discharges  it  into  the  greater  coronary 
just  as  the  latter  is  entering  the  right  auricle.  Some 
smaller  veins  are  also  described  about  the  roots  of  the  aorta 
and  pulmonary  artery,  discharging  into  the  right  auricle 
by  several  orifices. 

The  nerves  of  the  heart  come  principally  from  the  cardiac 
plexus  of  the  sympathetic,  and  follow  the  course  of  the 
coronary  arteries.     Branches  also  are  traced  from  the  par  • 
vagum. 

Function. — The  office  of  the  heart  has  already  been  stated 
to  be,  to  circulate  the  blood,  in  which  function  it  is  the 
prime  agent.  The  venous  blood  is  returned  from  all  parts 
of  the  body  by  the  ascending  and  descending  cava,  and 
coronary  vein,  into  the  right  auricle  of  the  heart.  This 


THE  HEART.  625 

auricle,  by  its  muscular  apparatus,  contracts,  and  throws 
the  blood  through  the  ostium  venosurn,  into  the  right  ven- 
tricle. This  ventricle  now  contracts  and  propels  the  blood 
into  the  pulmonary  artery  ;  the  tricuspid  valve  preventing 
its  return  into  the  auricle.  The  pulmonary  artery  con- 
ducts the  blood  to  the  air  cells  of  the  lungs,  where  it  is 
changed  from  venous  into  arterial,,  as  already  explained 
under  the  head  of  respiration,  and  its  return  to  the  ven- 
tricle is  prevented  by  the  semilunar  valves  placed  at  the 
mouth  of  the  artery.  From  the  lungs  it  is  carried  by  the 
four  pulmonary  veins  to  the  left  side  of  the  heart,  into  the 
left  auricle,,  thus  completing  a  circle  from  the  right  to  the 
left  auricle,  called  the  pulmonic  or  lesser  circulation. 

The  left  auricle  now  contracts  and  throws  the  blood 
through  the  ostium  arteriosum,  into  the  left  ventricle,  which 
in  turn  contracts  and  propels  it  into  the  aorta ;  the  mitral 
valve  between  the  auricle  and  ventricle,  and  the  semilunar 
valves  at  the  mouth  of  the  aorta,  preventing  any  regurgi- 
tation.  From  the  aorta  it  passes  to  every  part  of  the  sys- 
tem, returning  by  the  vena  cava  to  the  right  side  of  the 
heart,  and  thus  completing  another  circle  called  the  systemic 
or  greater  circulation. 

In  the  passage  of  the  blood  through  the  heart,  two  dis- 
tinct sounds  are  heard,  known  as  the  sounds  of  the  heart. 
The  first  sound  is  dull,  prolonged,  and  corresponds  with  the 
contraction  of  the  ventricles,  and  the  impulse  of  the  heart 
against  the  ribs.  The  second  sound,  compared  to  a  click,  is 
sharp,  clear,  and  quick,  and  corresponds  to  the  diastole  of 
the  heart.  The  two  sounds  embrace  one  arterial  pulsation. 
The  two  auricles  contract  synchronously,  so  likewise  the 
two  ventricles.  The  first  sound,  it  is  believed,  results  from 
the  contraction  of  the  muscular  fibres  of  the  ventricles,  the 
impulse  of  the  heart's  apex  against  the  ribs,  and  the  rush  of 
the  blood  through  the  aorta  and  pulmonary  artery.  The 
second  sound  is  thought  to  arise  from  the  sudden  filling  and 
quick  closure  of  the  semilunar  valves,  by  the  reflux  of  the 
blood  during  the  diastole  of  the  ventricles,  and  the  recoil  of 
the  elastic  coat  of  the  arteries ;  other  opinions  are  enter- 
40 


626  THE  AORTA. 

tained  in  reference  to  the  origin  of  these  sounds,  which  it  is 
not  thought  necessary  to  notice  further  in  a  work  like  the 
present. 

THE  AORTA,    (Fig.    8.) 

The  origin,  course,  and  termination  of  the  aorta,  together 
with  a  general  outline  of  its  primary  and  prominent  sec- 
ondary branches,  will  he  found  under  the  head  of  the  vas- 
cular tissue.  A  detail  of  the  several  branches,  supplying 
the  various  organs  contained  in  the  cranial,  abdominal, 
and  thoracic  cavities,  the  exceptions  hereafter  to  be  no- 
ticed, have  also  been  given  in  connection  with  the  exam- 
ination of  each  of  these  organs.  So  that  all  we  propose, 
in  the  present  place  is,  a  brief  recapitulation  of  the  primary 
branches  of  the  aorta,  in  the  order  in  which  they  suc- 
cessively arise  from  this  tube,  and  the  organs  and  vis- 
cera to  which  they  are  respectively  distributed,  so  as  to 
fix,  more  firmly  in  the  memory,  the  chain  of  connection 
between  these  two  great  classes  of  organs,  and  their  relative 
dependency. 

The  aorta,  it  is  known,  comprises  the  great  trunk  or 
arterial  half  of  the  general  or  systemic  circulation.  Com- 
mencing in  the  upper  portion  of  the  left  ventricle  of  the 
heart,  concealed  by  the  pulmonary  artery,  it  ascends  to  the 
right  side,  on  a  level  with  the  second  rib  and  its  cartilage; 
then  crosses  behind  the  sternum,  about  an  inch  below  its 
upper  edge,  to  the  left  side,  when  it  turns  downward  and 
inward  to  the  third  or  fourth  dorsal  vertebra.  To  this 
point  a  curvature  is  described,  constituting  the  arch  of  the 
aorta,  which  consists  of  an  ascending,  transverse,  and  de- 
scending portion.  From  the  arch,  the  aorta  continues 
descending  upon  the  left  side  of  the  vertebral  column, 
through  the  thoracic  cavity,  to  the  diaphragm,  to  which 
point  it  is  called  thoracic  aorta.  Passing  beneath  the  crura 
of  the  diaphragm,  it  enters  the  abdomen  and  traverses  this 
cavity  upon  the  median  line,  to  the  space  between  the 
fourth  and  fifth  lumbar  vertebras,  where  it  terminates  by 
dividing  into  the  common  or  primitive  iliac  arteries. 


THE  VENA  CAVA.  62f 

This  portion  is  styled  the  abdominal  aorta.  The  first 
branches  given  off  by  the  aorta,  are  those  supplying  the 
heart,  and  consist  of  the  right  and  left  coronary.  The  next 
branches  in  order  are  those  coming  off  from  the  arch,  and 
are  the  arteria  innominata,  the  left  carotid,  and  the  left  sub- 
clavian,  which  supply  the  neck,  head,  upper  extremities, 
and  part  of  the  wails  of  the  chest. 

The  branches  of  the  thoracic  aorta  (Figs.  8  and  214) 
come  next,  and  consist  of  the  bronchial  arteries,  which  go 
to  the  lungs ;  the  cesophageal,  five  or  six  in  number,  to  the 
oesophagus ;  the  posterior  mediastinal  to  the  mediastinum ; 
and  the  intercostal  to  the  intercostal  spaces  and  walls  of 
the  chest.  The  superior  intercostal  comes  from  the  sub- 
clavian.  All  these  arteries  are  in  pairs. 

The  abdominal  aorta,  (Figs.  8  and  214,)  the  last  portion 
of  this  tube,  gives  off  the  phrenic  to  the  diaphragm.  The 
cceliac,  a  single  trunk,  divides  into  three  branches — the 
gastric,  hepatic,  and  splenic,  which  go  to  the  stomach,  liver, 
and  spleen. 

The  superior  mesenteric  artery,  about  an  inch  below  the 
coeliac,  supplies  the  small  intestines,  the  right  ascending, 
and  transverse  portion  of  the  large  intestine. 

The  emulgent  or  renal  arteries,  two  in  number,  come  off 
at  right  angles,  and  go  to  the  kidneys. 

The  spermatic,  long  and  small,  descend  to  the  testicles. 
These  are  sometimes  branches  of  the  renal. 

The  inferior  mesenteric,  a  single  trunk,  supplies  the  left 
colon  and  rectum. 

The  lumbar  arteries  are  in  pairs,  from  three  to  five  in 
number,  and  supply  the  abdominal  walls. 

THE  SUPERIOR  AND  INFERIOR   VENA  CAVA,    (Fig.  9.) 

These  two  great  veins,  called  also  the  ascending  and  de- 
scending cava,  with  the  coronary,  return  all  the  blood  of 
the  body,  and  constitute  the  venous  portion  of  the  systemic 
or  general  circulation. 

The  descending  or  superior  cava  returns  to  the  right 
auricle  of  the  heart  all  the  blood  of  the  body  from  above 
the  diaphragm. 


628  THE  VENA  AZYGOS. 

The  sinuses  of  the  brain,  emerging  at  the  base  of  the 
cranium,  become  the  internal  jugular  veins,  which,  with 
the  external  jugulars,  descend  the  neck,  and  at  the  root  of 
the  latter  unite  with  the  subclavian  upon  either  side,  and 
form  the  right  and  left  vena-innominata,  the  junction  of 
which,  behind  the  cartilage  of  the  first  rib  upon  the  right 
aide,  constitutes  the  superior  cava. 

This  great  vein  is  about  three  inches  in  length,  and  de- 
scends within  the  pericardium  to  enter  the  upper  portion 
of  the  right  auricle.  It  has  in  front  of  it  the  remains  of 
the  thymus  gland  and  some  cellular  structure ;  behind  is 
the  right  pulmonary  artery  and  the  pulmonary  vein  ;  upon 
the  right  is  the  phrenic  nerve  and  right  lung ;  upon  the 
left  or  internally  is  the  ascending  aorta.  Just  as  it  enters 
the  pericardium  it  receives  at  its  posterior  part  the  vena 
azygos. 

The  vena  azygos  (Fig.  9)  returns  the  blood  chiefly  of  the 
parietes  of  the  chest.  It  commences  in  the  abdomen,  op- 
posite the  second  lumbar  vertebra,  by  branches  from  the 
superior  lumbar  veins,  and  sometimes  also  from  the  renal 
and  spermatic,  with  an  occasional  branch  from  the  inferior 
cava.  Thus  formed,  it  ascends  through  the  aortic  opening 
in  the  diaphragm  to  the  thorax,  and  continues  upward  in 
the  posterior  mediastinum  upon  the  right  side  of  the  verte- 
bral column,  having  the  thoracic  duct  and  aorta  upon  its 
left,  and  the  splanchnic  nerve  upon  its  right.  It  increases 
in  size  as  it  ascends,  and  about  the  fourth  dorsal  vertebra 
arches  over  the  root  of  the  right  lung  to  terminate  in  the 
superior  cava,  where  a  valve~Ms  found  to  prevent  regurgita- 
tion. 

This  vein  in  its  course  receives  the  intercostal  veins  of 
the  right  side,  the  azygos  minor  or  vena  Jiemiazygos  of  the 
left  side,  which  is  formed  from  the  superior  left  lumbar 
veins,  *nd  as  it  ascends  receives  the  six  or  seven  left  infe- 
rior intercostals.  It  crosses  the  spine  about  the  sixth  or 
seventh  dorsal  vertebra  behind  the  aorta  and  thoracic  duct, 
and  joins  the  right  or  great  vena  azygos.  The  five  or  six 
left  superior  intercostal  veins  constitute  what  has  been 


NERVES  OF  THORAX  AND  ABDOMEN.          629 

called  a  superior  vena  azygos,  which  empties  into  the  left 
vena  innominata,  and  connects  also  with  the  lesser  azygos. 
The  vena  azygos  also  receives  the  bronchial,  cesophageal, 
and  mediastinal  veins. 

The  inferior  or  ascending  cava  (Fig.  9)  returns  all  the 
blood  of  the  body  from  below  the  diaphragm.  The  two 
primitive  or  common  iliac  veins,  formed  by  the  junction  of 
the  external  and  internal  iliacs  at  the  sacro-iliac  articula- 
tion, converge  upon  the  right  side,  and  unite  upon  th& 
ligament  between  the  fourth  and  fifth  lumbar  vertebrae  to 
constitute  the  commencement  of  the  ascending  cava. 

This  great  vein  now  ascends  upon  the  right  side  and 
partly  in  front  of  the  spinal  column,  on  the  right  psoas 
muscle,  and  right  crus  of  the  diaphragm,  havinsj  the  aorta 
upon  the  left — enters  the  fissure  in  the  posterior  part  of  the 
liver,  and  ascends  through  the  tendinous  opening  in  the 
diaphragm,  to  which  it  strongly  adheres,  to  terminate  in 
the  inferior  and  back  part  of  the  right  auricle.  In  its 
course  it  receives  the  lumbar,  renal,  spermatic,  phrenic,  and 
hepatic  veins. 

The  veins  of  the  stomach,  pancreas,  spleen,  and  intes- 
tines, go  to  form  the  great  portal  vein,  which  is  described 
under  the  head  of  the  vascular  tissue. 

NERVES  OF  THE  THORAX  AND  ABDOMEN. 

These  nerves  comprise  the  sympathetic,  the  thoracic 
spinal,  the  lumbar  spinal,  pneumogastric,  and  phrenic. 

The  sympathetic  in  the  chest  (Fig.  155)  consists  of  twelve 
dorsal  ganglia  with  their  several  branches.  The  ganglia 
are  situated  upon  the  heads  of  the  ribs,  covered  by  the 
pleura  costalis  and  a  thin  fascia.  Their  form  is  triangular 
and  flat,  the  apex  external,  and  the  base,  looking  to  the 
spine.  They  are  small,  and  present  the  usual  gray  color 
and  pearl v  lustre  of  the  rest  of  the  ganglia  composing  *the 
sympathetic  system.  They  are  connected  above  and  below 
to  each  other  by  branches  called  superior  and  inferior.  The 
other  branches  are  external  and  internal. 

The  external  branches,  two  and  sometimes  more,  or  onlj 


630 


SYMPATHETIC  NERVE. 


one  in  number,  pass  obliquely  upward  and  outward  to  join 
the  corresponding  spinal  nerve,  though  a  twig  is  sometimes 
sent  to  the  intercostal  FIG.  202.  mediastinum,  following 
nerve  below.  The  in- 
ternal branches  consist 
of  the  mediastinal  and 


splanchnic.     The   for- 
mer enter  the  posterior 


the  course  of  the  inter- 
costal arteries  to  the  aor- 
ta on  both  of  which  they 
ramify  in  the  form  of 
plexuses.  Other  branch- 
es are  traced  upon  the 
oasophagus,  the  longus 
colli  muscle,  and  into  the 
cardiac  and  pulmonary 
plexuses.  The  splanchnic  nerves 
are  divided  into  the  great  and 
less.  The  great  splanchnic  comes 
from  the  sixth,  seventh,  eighth,  ninth 
and  tenth  ganglia,  by  several  distinct 
roots.  These  descend  obliquely  upon  the 
sides  and  front  of  the  dorsal  vertebrae,  to 
about  the  tenth  or  eleventh,  where  they 
unite  into  a  common  trunk,  which  is  large 
and  passes  through  the  diaphragm  either 
by  piercing  it,  or  along  with  the  aorta  to 
terminate  in  the  semilunar  ganglion.  The  lesser  splanchnic 
derives  its  roots  from  the  tenth  and  eleventh  ganglia. 
These  roots,  uniting,  enter  the  abdomen  through  the  crus 
of  the  diaphragm,  external  to  the  great  splanchnic,  and  go 
to  the  renal  plexus. 

The  sympathetic  nerve  in  the  abdomen  (Fig.  155)  com- 
prises the  semilunar  ganglion  and  its  various  plexuses,  with 
the  lumbar  ganglia. 

The  semilunar  ganglion  is  situated  upon  either  side  of 
the  coaliac  artery,  and  by  some  is  regarded  as  the  grand 

FIG.  202  represents  the  connection  of  the  Sympathetic  Nerve  with  the 
Spinal,  a  a  Anterior  fissure  of  the  spinal  marrow  6  Motor  or  anterior  root 
of  the  spinal  nerve,  c  Posterior  root,  d  Ganglion  on  the  posterior  root.  // 
Spinal  nerve,  e  Its  posterior  branch,  g  Its  anterior  hranch.  h  h  Two  tho- 
racic ganglia  of  the  sympathetic,  i  Sympathetic  trunk  connecting  the  ganglia. 
j  fc  Two  filaments  uniting  the  sympathetic  and  spinal  nerve. 


SYMPATHETIC  NERVE.  631 

centre  of  the  sympathetic  system.  It  consists  of  a  series  of 
ganglia,  more  numerous  on  the  right  than  the  left  side, 
about  an  inch  in  length  and  presenting  a  semicircular  form; 
several  of  these  are  sometimes  fused  into  one.  They  all 
communicate  and  send  off  an  immense  number  of  radiating 
filaments,  constituting  the  solar  plexus. 

This  plexus  (Fig.  203)  is  situated  behind  the  stomach, 
above  the  pancreas,  and  within  the  epigastric  region,  and 
receives  branches  from  the  lesser  splanchnic,  the  phrenic, 
and  the  right  vagus.  From  this  central  and  great  plexus, 
nervous  filaments  proceed  in  every  direction,  and  mostly 
follow  the  course  of  the  arteries,  around  each  of  which  they 
form  a  plexus,  receiving  its  name  from  the  artery  it  accom- 
panies. Thus  we  have  enumerated  the  following  different 
plexuses  : 

The  phrenic,  composed  of  branches  coming  from  the 
solar  plexus,  accompanies  the  phrenic  arteries  to  the  dia- 
phragm. 

The  gastric  plexus  goes  along  the  coronary  artery  to  the 
stomach,  where  it  communicates  with  the  vagi. 

The  hepatic  plexus  takes  the  course  of  the  hepatic  artery 
to  the  liver.  Branches  also  accompany  the  vena  portaa 
and  right  gastro-epiploic  artery  to  the  greater  curvature 
of  the  stomach. 

The  splenic  plexus  follows  the  splenic  artery  to  the 
spleen,  sending  off  branches  to  the  pancreas  and  head  of 
the  stomach,  and  along  the  left  gastro-epiploic  artery  to 
the  greater  curvature  of  the  stomach. 

The  superior  mesenteric  plexus  surrounds  the  superior 
mesenteric  artery,  and  its  branches  supply  the  small  in- 
testines, co3cum,  ascending,  and  transverse  colon. 

The  renal  plexus  attends  the  renal  arteries  to  the  kid- 
neys. This  plexus  gives  off  filaments  to  the  supra-renal 
capsules,  called  supra-renal  plexus ,  and  also  filaments  along 
the  spermatic  artery,  called  the  spermatic  plexus,  to  the 
testes  of  the  male,  and  ovary  of  the  female. 

The  inferior  mesenteric  plexus  follows  the  course  of  the 
inferior  mesenteric  artery,  and  supplies  the  descending 


632 


SYMPATHETIC  NERVE. 


FIG.  203. 


and  sigmoid  flexure  of  the  colon.     It  sends  off  filaments 

called  the  hcemorrhoidal  plexus,  which  follow  the  heemor- 

rhoidal  arteries  to  the  rectum. 

The  lumbar  ganglia  are  four  or  five  in  number,  situated 

upon  the  bodies  of  the  lumbar  vertebras,  and  connected 

with  the  thoracic  by  a 
cord  which  descends  be- 
hind the  diaphragm  close 
to  the  spine  to  join  the 
first  lumbar  ganglion. 
These  ganglia  also  send 
off  external  and  internal 
branches.  The  external 
communicate  by  two  or 
three  branches  with  the 
lumbar  nerves.  The  in- 
ternal surround  the  aorta, 
forming  the 

Aortic  Plexus. — This 
plexus  receives  filaments 
from  the  inferior  mesen- 
teric,  and  descends  into 
the  pelvis,  where,  in  front 
of  the  sacrum,  it  forms 
the  hypogastric  plexus. 
This  latter  plexus  com- 
municates with  the  sacral, 
and  sends  filaments  to 
the  pelvic  organs,  which 
will  be  noticed  in  another 
place. 
The  thoracic  spinal  nerves  (Fig.  14)  are  twelve  in  num- 

Fio.  203  represents  the  plexuses  of  the  Sympathetic  Nerve.  I  Dorsal  gan- 
glia of  the  sympathetic,  with  the  roots  of  the  great  splanchnic  nerve  arising 
from  them,  m  Lesser  splanchnic  nerve,  o  Solar  plexus.  «  Renal  plexus. 
p  Mesenteric  plexus,  q  Lumbar  ganglia,  r  Sacral  ganglia,  s  Vesical  plexus. 
t  Rectal  plexus,  u  Lumbar  plexus  (spinal.)  v  Rectum,  w  Bladder.  * 
Pubis.  y  Crest  of  ilium,  z  Kidney,  o  o  Aorta.  6  6  Diaphragm,  c  c  Heart 
and  cardiac  plexus,  d  d  Larynx. 


THORACIC  SPINAL  NERVES.  633 

ber  on  each  side.  They  arise  by  filaments  from  the  ante- 
rior and  posterior  root  of  the  spinal  marrow,  and  pass  out 
through  the  intervertebral  foramina ;  each  nerve  then 
divides  into  an  anterior  and  posterior  branch.  The  ante- 
rior branches  occupy  the  intercostal  spaces,  pursue  the  course 
of  the  intercostal  arteries,  and  are  called  the  intercostal 
nerves.  Each  receives  two  branches  from  the  thoracic 
ganglia  of  the  sympathetic,  and  then  runs  along  the  groove 
on  the  under  margin  of  each  rib,  between  the  two  laminae 
of  the  intercostal  muscles.  The  five  or  six  upper  intercos- 
tal nerves  pass  round  to  the  sternum,  and  when  near  the 
latter,  emerge  from  between  the  intercostal  muscles,  and 
are  distributed  upon  the  pectoral  muscles  and  integuments. 
The  five  or  six  lower  nerves  supply  the  abdominal  muscles 
and  their  integuments. 

The  first  anterior  thoracic  nerve  joins  the  last  cervical, 
and  sends  a  branch  on  the  inner  face  of  the  first  rib,  which 
goes  to  supply  the  intercostal  muscles.  The  second  ante- 
rior thoracic,  or  dorsal  nerve,  in  addition  to  the  ordinary 
distribution,  sends  a  branch  between  the  ribs,  which  passes 
outward  to  the  axilla,  there  joins  the  internal  cutane- 
ous of  the  upper  extremity,  and  then  descends  the  arm, 
distributing  filaments  upon  the  integuments  as  far  as  the 
elbow.  The  third  anterior  dorsal  also  sends  a  branch  to 
the  axilla,  which  supplies  the  integuments  on  the  inner  side 
of  the  arm.  These  nerves  are  called  intercosto-humeral,  or 
the  nerves  of  Wrisberg,  and  are  supposed  to  explain  the 
numbness  of  the  arm  in  angina  pectoris. 

The  lower  intercostal  nerves,  about  the  middle  of  the  ribs, 
send  off  branches,  called  external  pectoral,  which  are  spent 
upon  the  muscles  and  integuments  upon  the  side  of  the 
chest.  The  continued  nerve,  which  is  the  intercostal  proper, 
emerges,  as  already  stated,  near  the  sternum,  and  supplies 
the  pectoral  muscles,  mamma,  and  integuments  on  the 
front  of  the  chest. 

The  posterior  branches  of  the  dorsal  spinal  nerves  are 
smaller  than  the  anterior.  They  pass  backward  between 
the  corresponding  transverse  processes  of  the  vertebrae, 


634 


ABDOMINAL  SPINAL   NERVES. 


FIG.  204. 


and  divide  into  external  and  internal  branches.  The  for- 
mer supply  the  longissimus  dorsi,  sacro-lumbalis,  trape- 
zius,  rhomboid,  latissimus  dorsi,  and  adjacent  integu- 
ment. The  internal  supply  the  multifidus  spinae,  the  long 
muscles  of  the  back,  and  can  likewise  be  traced  to  the 
integuments. 

The  abdominal  spinal,  or  lumbar  nerves. — These  consist 

of  five  pairs,  and  are 
larger  than  the  dorsal. 
They  pass  through  the 
intervertebral  foramina, 
the  first  pair  between 
the  first  and  second 
lumbar  vertebras  —  the 
fifth  between  the  last 
vertebra  and  the  sa- 
crum. Like  the  dorsal, 
these  nerves  consist  of 
anterior  and  posterior 
branches.  The  anterior 
are  the  largest,  and  pass 
through  and  behind  the 
psoas  magnus,  uniting 
with  each  other  to  con- 
stitute the  lumbar  plexus. 
The  first  lumbar  unites 
with  the  last  dorsal. 

The  lumbar  plexus  is  concealed  by  the  psoas  magnus 
muscle,  and  is  situated  upon  the  sides  of  the  lumbar  verte- 
brae in  front  of  their  transverse  processes. 

The  branches  of  this  plexus  are  divided  into  the  super- 
ficial and  terminal.  The  superficial  are  again  divided  into 
the  abdomino-crural  and  genito-crural,  and  consist,  accord- 

FIG.  204  represents  the  Lumbar  and  Ischiatic  Plexuses,  a  Lumbar  plexus. 
.  6  Ischiatic  plexus,  c  c  Abdominal  crural  nerves,  d  External  cutaneous 
nerve,  e  f  g  Cutaneous  branches  from  h  Anterior  crural  nerve,  i  Genito- 
crural.  j  j  Termination  of  the  sympathetic,  k  Iliacus  internus  muscle.  I 
Broad  muscles  of  the  abdomen,  m  Psoas  magnus.  n  Bodies  of  lumbar  verte- 
bra, o  Quadratus  lumborum.  p  Diaphragm,  q  Sartorius  muscle. 


ABDOMINAL  SPINAL  NERVES.  635 

ing  to  Bichat,  of  the  superior,  middle,  and  inferior  musculo- 
cutaneous. 

The  superior  musculo-cutaneous  (called  also  external  ilio- 
inguinal,  ilio-liypogastric,  ilio-scrotal)  conies  from  the  supe- 
rior part  of  the  plexus,  passes  outwardly  through  the  psoas 
inagnus  to  the  quadratus  lumborum,  and  thence  to  the 
back  part  of  the  crest  of  the  ilium, — here  it  divides  into  an 
external  and  internal  branch.  The  former  supplies  the  ab- 
dominal muscles  and  integuments.  The  internal  can  be 
traced  forward  to  the  anterior  superior  spinous  process  of 
the  ilium,  and  thence  across  parallel  with  Poupart's  liga- 
ment to  near  the  rectus,  where  it  perforates  the  external 
oblique,  and  becomes  cutaneous  upon  the  pubic  and  ingui- 
nal regions. 

The  middle  musculo-cutaneous ,  or  inguino-cutaneous ,  has 
nearly  a  similar  origin  and  distribution  with  the  last. 

The  inferior  musculo-cutaneous,  or  external  cutaneous , 
comes  from  the  first  or  second  lumbar,  passes  along  the 
iliacus  muscle,  and  between  the  anterior  superior  and  an- 
terior inferior  spinous  processes,  divides  into  an  anterior  and 
posterior  branch.  The  former  perforating  the  fascia  lata 
about  three  or  four  inches  below  Poupart's  ligament,  be- 
comes cutaneous,  distributing  filaments  as  low  as  the  knee. 
The  posterior  is  spent  on  the  outer  and  back  part  of  the 
thigh,  either  passing  through  or  behind  the  tensor  vaginse 
femoris. 

The  genito  crural  comes  from  the  second  or  third  lumbar 
nerve.  The  genital  or  spermatic  branch  joins  the  cord  at  the 
internal  ring,  supplies  the  cremaster,  and  terminates  upon 
the  integuments  of  the  scrotum  and  pubis,  and  in  the  female 
upon  the  labium.  The  crural  goes  beneath  Poupart's  liga- 
ment, pierces  the  sheath  of  the  femoral  vessels,  sending 
some  filaments  in  company  with  the  artery,  passes  through 
the  fascia  lata,  and  supplies  the  integuments  upon  the  front 
of  the  thigh  as  far  as  its  middle. 

The  terminal  branches  of  the  lumbar  plexus  are  the  ante- 
rior crural,  obturator,  and  lumbo-sacral. 

The  anterior  crural  (or  femoral  nerve)  comes  from  the 


636  ABDOMINAL  SPINAL  NERVES. 

superior  lumbar  nerves,  and  is  the  largest  nerve  of  the  lum- 
bar plexus.  It  passes  behind,  and  sometimes  through  the 
psoas  muscle,  and  descends  to  Poupart's  ligament,  beneath 
which  it  passes  about  half  an  inch  to  the  outside  of  the 
femoral  artery,  where  it  divides  into  numerous  muscular 
and  cutaneous  branches.  In  the  pelvis  it  distributes  fila- 
ments to  the  psoas  and  iliac  muscles. 

The  obturator  nerve  comes  from  the  third  or  fourth  lum- 
bar, passes  through  the  psoas  muscle,  and  descends  along 
the  inner  edge  of  the  latter  to  the  obturator  foramen, 
through  which  it  passes  to  the  inner  side  of  the  thigh, 
where  it  divides  into  an  anterior  and  posterior  branch,  which 
supply  the  muscles  chiefly  on  the  inner  thigh,  the  adduc-. 
tors,  gracilis,  vastus  internus,  &c.,  as  well  as  the  integu- 
ments, and  anastomoses  with  the  vaginal  branches  of  the 
crural ;  one  long  branch  is  traced  as  low  down  as  the  po- 
piteal  space,  to  the  back  part  of  the  knee  joint. 

The  lumbo-sacral  nerve  comes  from  the  fourth  and  fifth 
lumbar,  and  descends  into  the  pelvis  to  join  the  sacral 
plexus. 

The  posterior  divisions  of  the  lumbar  nerves  pass  back- 
ward between  the  transverse  processes,  and  supply  the 
multifidus  spinae,  longissimus  dorsi,  and  sacro-lumbalis 
muscles,  and  the  integuments.  Varieties  will  be  seen  in 
the  number  and  distribution  of  the  branches  of  the  lumbar 
plexus. 

The  sacral  nerves  (Fig.  204)  consist  of  six  pair.  They 
divide  within  the  spinal  canal  into  anterior  and  posterior 
branches,  which  pass  out  at  the  anterior  and  posterior 
sacral  foramina.  The  posterior  are  quite  small,  and  supply 
the  muscles  and  integuments  on  the  back  of  the  sacrum. 

The  anterior  are  large,  the  four  superior  of  which,  with 
the  last  lumbar  uniting  together,  constitute  the  sacral 
plexus.  These  nerves  all  receive  branches  from  the  sacral 
ganglia  of  the  sympathetic.  The  fifth  and  sixth  are  very 
small,  sometimes  absent,  and  escape  between  the  sacrum 
and  coccyx 

The  sacral  or  sciatic  plexus  is  situated  upon  the  side  of 


THE  KIDNEYS.  637 

the  rectum,  in  front  of  the  pyriformis  muscle,  and  behind 
the  pelvic  fascia.  Its  branches  are  divided  into  internal  and 
external.  The  former  are  distributed  to  the  pelvic  viscera, 
the  latter,  consisting  of  the  greater  and  lesser  ischiatic,  glu- 
teal,  and  pudic,  go  principally  to  the  lower  extremity.  All 
of  these  will  be  noticed  in  connection  with  the  organs 
they  severally  supply. 


CHAPTEK  V. 

ACTIVE    ORGANS    OF    THE    TRUNK. 

FOURTH     DIVISION. 
THE   ORGANS  OP  URINATION. 

THESE  organs  consist  of  the  Kidneys,  the  Ureters,  and 
the  Bladder. 

SECTION    I. 
THE  KIDNEYS. 

The  kidneys  are  two  firm,  solid  bodies,  situated  in  the 
lumbar  regions,  at  their,  posterior  portion,  extending  be- 
tween the  crest  of  the  ilium  and  the  last  rib — lying  upon 
the  psoas  magnus,  quadratus  lumborum,  and  diaphragm, 
and  corresponding  to  the  two  last  dorsal,  and  two  upper 
lumbar  vertebrae. 

Their  form  is  that  of  the  kidney-bean.  Their  size  is 
about  four  inches  in  length,  and  two  in  width.  Their 
average  weight  is  estimated  at  from  three  to  four  ounces. 
Their  color  is  a  dark,  brownish  red. 

The  anterior  surface  of  each  kidney  is  convex,  the  right 
having  the  ascending  colon  and  duodenum  upon  it;  the 
left  the  descending  colon,  and  both  of  them  the  peritoneum 
upon  this  same  surface.  The  posterior  surface  is  flat.  In 
the  foetus  both  surfaces  present  the  lobulated  appearance. 
The  outer  margin  is  smooth  and  convex ;  the  inner  presents 
a  notch,  hilus  renalis,  where  the  vessels  and  nerves  enter 
and  pass  out.  The  upper  end  of  each  kidney  is  larger, 


638 


THE  KIDNEYS. 


rounder,  and  nearer  the  spine,  than  the  lower  end,  and  is 
also  surmounted  by  the  renal  capsule. 

The  kidneys  are  seen  to  vary  in  number,  sometimes  there 
FIG.  205.  being  only  one, 

which  is  quite 
large,  and  ex- 
tending across 
the  spine.  The 
two  kidneys  are 
sometimes  con- 
nected by  a 
transverse  band, 
and  Dr.  Homer 
cites  an  instance 
where  one  of  the 
kidneys  was  in 
the  pelvis  in 
front  of  the  rec- 
tum. 

The  kidneys 
are  essentially 
glandular  or- 

and  each  consists  of  membranes,,  two  distinct  sub- 
stances, the  cortical  and  tubular,  the  excretory  ducts,  blood- 
vessels and  nerves. 

Three  membranes  are  given  to  the  kidney,  a  serous,  cel- 
lulo-adipose,  and  fibrous.  The  first  comes  from  the  peri- 
toneum, and  is  partial,  covering  only  the  anterior  surface. 
Of  the  second,  or  celMo-adipose,  the  cellular  portion  prevails 
in  the  young,  while  the  adipose  is  most  abundant  in  the 
adult.  The  third  orfbrous  is  the  proper  coat  of  the  kidney. 
It  forms  a  capsule  which  completely  envelops  the  surfaces, 
and  enters  the  hilus  along  with  the  blood-vessels.  This 
membrane,  as  already  stated,  is  fibrous,  and  is  also  strong, 
elastic,  smooth,  and  semi-transparent.  It  adheres  to  the  sur- 

FIG.  205  represents  the  Urinary  Apparatus,  a  a  Kidneys.  6  6  Capsulae 
renalis.  c  c  Ureters,  d  Bladder,  t  Rectum.  /  Renal  arteries,  g  Aorta. 
h  Its  division  into  the  iliacs.  t  Point  where  ureters  cross  the  iliacs. 


THE  KIDNEYS.  639 

face  of  the  kidney  by  delicate  cellular  and  vascular  fila- 
ments, which  are  easily  torn  on  raising  it,  and  which  are 
traced  into  its  substance.  It  preserves  the  form  of  the 
kidney. 

On  making  a  section  of  the  kidney  from  its  convex  to  its 
concave  portion,  two  distinct  substances  are  noticed,  the 
external  or  cortical,  and  the  internal  or  tubular.  The  cortical 
forms  the  superficial  layer,  is  about  FIG.  206^ 

two  lines  in  thickness,  though  vary- 
ing at  different  points,  and  sends  pro- 
cesses towards  the  centre  of  the  gland 
between  the  tubular  portion,  thus 
dividing  the  latter  into  as  many 
separate  parts  assuming  the  form  of 
distinct  cones.  Its  color  is  a  reddish 
brown,  and  it  is  also  called  vascular 
from  the  quantity  of  blood-vessels  ^ 
with  which  it  is  supplied. 

On  being  torn,  a  number  of  gran- 
ules are  seen,  which  seem  to  compose 
the  great  body  of  the  cortical  portion,  and  are  called  the 
corpora,  or  acini  of  Halpiglii.  These  acini  exist  in  immense 
numbers,  and  are  seen  as  very  minute,  round,  red  points, 
their  diameter  being  about  the  tenth  of  a  line.  Their  con- 
nection with  arterial  branches  is  compared  to  that  of  ber- 
ries with  their  stems.  Some,  among  whom  is  the  distin- 
guished Euysch,  regard  the  acini  as  consisting  wholly  of 
blood-vessels,  while  others  view  them  as  little  glandular 
sacs  for  secreting  the  urine,  around  whose  walls  the  blood- 
vessels are  ramified,  and  from  which  arise  the  commencing 
uriniferous  or  excretory  ducts. 

According  to  Mr.  Bowman,  these  acini  are  composed  of 
capillary  arteries  coiled  up  in  loops  and  closely  compressed, 
so  as  to  form  vascular  balls,  which  are  enclosed  in  dilata- 
tions of  the  urinary  tubes,  forming  capsules  for  each. 

FIG.  206  represents  a  section  of  the  right  Kidney,  having  the  renal  capsule 
on  its  top.  1  Supra-renal  capsule.  2  Cortical  portion.  3  Medullary  or 
tubular  portion.  4  Calyces.  5  Infundibula.  6  Pelvis.  7  Ureter. 


640  THE  KIDNEYS. 

Each  capsule  is  perforated  by  an  artery  called  vas  inferens, 
which  goes  to  form  this  vascular  ball,  and  from  the  inte- 
rior of  each  there  passes  out  through  the  capsule  a  small 
vein  called  vas  ejferens,  which,  with  other  veins  of  like 
kind,  goes  to  the  venus  plexus  surrounding  the  convoluted 
urinary  tubes.  Two  systems  of  vessels  are  here  described, 
first  the  arterial  capillary,  composing  the  acini  of  Malpighi 
within  the  urinary  capsule,  and  second,  the  venous  capillary 
on  the  outside  of  the  capsule  surrounding  the  urinary 
tubes,  and  constituting  a  plexus  which  is  compared  to  the 
portal  plexus  of  the  liver.  This  plexus  is  believed  by  Mr. 
Bowman  to  secrete  the  urea,  lithic  acid,  and  other  solid 
portions,  while  he  assigns  to  the  arterial  plexus  or  acini, 
the  separation  of  the  water  and  soluble  elements  of  the 
urine. 

The  internal  or  tubular  portion,  (Fig.  206,)  called  also 
pyramides  Malpighi,  consists  of  fine  tubes  collected  in  fasci- 
culi, forming  cones,  of  which  there  are  about  fifteen.  These 
cones  are  of  a  dense  structure  and  pale  color,  with  their 
bases  at  the  circumference,  and  their  apices  at  the  central 
cavity  of  the  kidney.  They  are  separated  and  surrounded 
by  the  cortical  substance,  constituting  the  several  conoidal 
fasciculi  so  many  distinct  lobes,  or  miniature  kidneys, 
which  are  distinctly  marked  upon  the  surface  of  the  foetal 
kidney.  The  apex  of  each  cone  is  free,  and  forms  a  projec- 
tion into  the  central  cavity  termed  papilla  or  mammary 
process. 

The  papillae  are  not  so  numerous  as  the  cones,  as  two  or 
more  of  the  latter  converge  into  one  of  the  former.  The 
papillae  are  arranged  into  an  anterior,  middle,  and  poste- 
rior row ;  and  each  one  presents  several  foramina,  through 
which  the  urine  passes  from  the  tubuli  uriniferi.  Each 
cone  or  pyramid  consists  of  a  collection  of  these  tubuli, 
which  are  more  numerous  at  the  base  than  at  the  apex,  in 
consequence  of  their  coming  together  as  they  approach  the 
latter.  They  are  compared  to  fine  hairs,  and  are  proven 
to  be  conductors  of  the  urine,  by  making  a  section  of  them 
and  squeezing  the  cortical  portion,  when  drops  of  urine 


THE  KIDNEYS.  641 

are  seen  to  ooze  out.  They  are  convoluted  tubes,  in  the 
cortex,,  called  the  tubes  of  Ferrein,  intertwining  here  with 
the  venous  and  arterial  capillaries,  and  ending  either  in 
loops  or  co3ca ;  while  in  the  pyramids  or  cones  these  tubes 
pursue  a  straight  course. 

The  papillae  are  surrounded  by  funnel-like  formations  of 
a  fibre-mucous  character,  called  infundibula.  The  papillae 
are  sometimes  more  numerous  than  the  infundibula,  in 
which  case  two  or  more  of  the  former  are  found  to  one  of 
the  latter.  The  infundibula  come  together  or  run  into 
each  other  so  as  to  form  three  compartments — one  in  the 
middle,  and  one  at  each  end  of  the  kidney,  which,  from 
their  cup-like  form,  are  termed  calyces,  and  these  calyces, 
by  their  union,  expand  into  the  oval  cavity,  at  the  inner 
margin  of  the  hilus,  constituting  the  pelvis  of  the  kidney. 

The  arteries  of  the  kidneys  are  the  renal  or  emulgent, 
and  come  from  the  aorta,  at  right  angles.  Each  divides 
into  six  or  more  branches,  which  enter  the  fissure  of  the 
kidney,  and  then  sub-divide  into  numerous  minute  vessels 
which  go  between  the  tubuli  to  the  cortex,  and  form  nu- 
merous inosculations,  constituting  a  capillary  net-work. 
The  veins  correspond  to  the  arteries,  though  they  are 
larger.  They  pass  out  of  the  kidney  at  the  fissure,  and  go 
to  the  vena  cava  ascendens.  The  left  renal  vein  is  longer 
than  the  right,  and  passes  in  front  of  the  aorta. 

The  lymphatics  are  described  as  numerous,  and  go  to  the 
lumbar  glands. 

The  nerves  come  from  the  solar  plexus,  lesser  splanchnic, 
and  lumbar  ganglia  of  the  sympathetic,  and  are  traced 
along  with  the  arteries. 

Renal  Capsules,  (capsulce  renales.) — These  bodies  are  two 
in  number,  and  are  also  called  supra-renal  or  atra-biliary 
bodies.  They  are  situated  at  the  superior  extremity  of 
each  kidney,  being  attached  by  cellular  structure  and 
blood-vessels.  Their  form  is  triangular,  with  the  base  con- 
cave, and  resting  upon  the  kidneys.  Their  color  is  of  a 
yellowish  brown,  and  their  size  is  variable,  being  much 
larger  in  the  foetus  than  in  the  adult. 
41 


642  THE  KIDNEYS. 

The  structure  of  these  bodies  consists  of  a  thick  mem- 
brane of  cellular  tissue,  which  surrounds  and  forms  their 
proper  coat,  and  processes  which  are  traced  within,  sep- 
arating its  several  parts.  In  the  centre  a  small  trian- 
gular cavity  is  seen,  containing,  in  the  foetus,  a  viscid 
reddish  fluid ;  in  the  child,  a  yellow  fluid ;  in  the  adult, 
a  dark  brown  liquid ;  while,  in  old  age,  it  is  almost  en- 
tirely empty. 

This  cavity  is  not  always  found,  and  by  some  is  denied 
to  exist  at  all,  and  when  present  is  attributed  either  to  the 
enlargement  of  a  vein,  decomposition,  or  laceration. 

The  arteries  come  from  the  renal,  aorta,  and  phrenic. 

The  veins  of  the  right  go  to  the  vena  cava  ascendens ; 
those  of  the  left  enter  the  emulgent. 

The  nerves  are  from  the  renal  and  solar  plexus.  Each 
capsule  is  divided  into  lobes,  and  these  again  have  been 
divided  into  lobules,  having  granules,  which  are  found  to 
be  connected  with  the  veins. 

Function. — The  use  of  the  renal  capsules  is  as  yet  un- 
known. In  the  foetus,  like  the  thymus  and  thyroid  bodies, 
they  are  large,  and  are  supposed  to  be  connected  with 
foetal  sanguification. 

Function  of  the  Kidneys. — The  use  of  these  glands,  it  is 
well  known,  is  to  secrete  the  urine  ;  and  the  cortical  por- 
tion of  the  kidney,  which  is  exceedingly  vascular,  has 
been  assigned  as  the  especial  part  where  the  secretion 
occurs,  while  the  tubular  conveys  the  fluid  down  the  coni- 
cal fasciculi  to  the  papilla?,  through  which  it  passes  into 
the  pelvis.  The  uriniferous  tubes  are  lined  by  mucous 
membrane,  and  are  found  by  Henle  to  contain  epithelial 
cells,  which,  as  in  other  glands,  are  regarded  as  the  true 
secreting  agents.  When  filled,  they  break  and  discharge 
into  the  tubuli  uriniferi,  others  being  formed  from  the 
nuclei  of  the  extinct  cells. 

The  urine  is  composed  principally  of  water.  It  also 
contains  urea.,  a  substance  highly  charged  with  nitrogen, 
and  also  lithic  or  uric  acid.  In  children  hippuric  acid  is 
found  instead  of  the  lithic.  Lactic  acid,  an  animal  extractive 


THE  URETERS.  643 

substance,  and  various  salts,  as  the  phosphate"  and  sulphate 
of  lime,  muriate  of  ammonia  and  soda,  and  salts  of  magne- 
sia, are  also  found  as  constituents  of  the  urine. 

SECTION    II. 

THE  URETERS. 

The  ureters,  (Fig.  205,)  one  for  each  kidney,  are  the  ex- 
cretory ducts,  and  extend  from  the  kidney  to  the  bladder, 
conveying  the  urine  from  the  former  into  the  latter.  Thej 
are  about  the  size  of  a  goose  quill,  and  of  an  average  length, 
of  eighteen  inches.  They  commence  in  the  pelvis  of  the 
kidney,  and  emerging  at  the  fissure  behind  the  vessels, 
take  a  course  downward  through  the  lumbar  regions,  upon 
the  anterior  surface  of  the  psoas  magnus,  and  behind  the 
peritoneum,  crossing  the  primitive  iliac  arteries  to  the 
pelvis,  which  they  enter.  Here  they  cross  the  internal 
iliacs  and  vasa  deferentia,  and  proceed  to  the  back  part  of 
the  bladder,  which  they  enter  by  passing  very  obliquely 
through  its  coats,  and  terminating  about  ten  or  twelve 
lines  from  the  neck.  In  the  female,  the  ureter  is  in  relation 
with  the  Fallopian  tubes  and  broad  ligaments. 

The  ureters  consist  of  two  coats,  an  outer  or  fibrous,  and 
an  inner  or  mucous  coat.  The  fibrous  is  composed  of 
dense  cellular  tissue.  The  mucous  is  pale,  without  valves, 
and  traced  into  the  bladder. 

These  tubes  are  larger  at  their  commencement  and  ter- 
mination than  in  the  middle.  They  are  capable  of  great 
dilatation,  as  seen  in  cases  of  obstructed  urine,  and  in  the 
passage  of  large  calculi  to  the  bladder,  in  which  condition! 
they  exhibit  the  greatest  sensibility. 

SECTION   III. 
THE  BLADDER,    (VESICA  URINARIA.) 

The  bladder  is  a  musculo-membranous  sac,  situated  mostly 
within  the  pelvis,  behind  the  pubis,  and  in  front  of  the  rec- 
tum. It  is  the  largest  of  all  the  reservoirs  of  secretion,  and 
receives  the  urine  from  the  ureters. 


644  URINARY  BLADDER. 

Its  position  and  capacity  vary  according  as  it  is  full  or 
empty,  and  also  according  to  age,  sex,  habit  and  disease. 
When  empty,  in  the  adult,  it  is  contracted  and  found  below 
and  behind  the  pubes,  and  presents  a  flat,  triangular  shape. 
When  moderately  distended,  it  rises  above  the  pubis,  in  con- 
tact with  the  recti  muscles,  and  in  front  of  the  peritoneum, 
and  assumes  the  form  of  an  ovoid,  the  larger  end  being  be- 
low upon  the  rectum,  the  smaller  end  above ;  when  com- 
pletely full,  it  rises  still  higher,  enlarging  more  and  more, 
and  having  its  larger  end  above  and  the  smaller  below.  In 
the  foetus  it  is  relatively  larger  than  in  the  adult.  In  the 
female  it  is  larger  than  in  the  male,  and  the  habit  of  retain- 
ing the  urine  renders  it  larger  than  when  the  calls  of  nature 
are  promptly  attended  to.  In  disease  every  variety  of  size 
and  the  highest  and  lowest  positions  are  seen. 

The  form  of  the  bladder  has  been  stated  to  be  ovoid  or 
FIG.  207.  egg-shape,  but  presenting  differen- 

ces according  to  causes  above  men- 
tioned. Its  direction  or  long  axis 
is  oblique  from  above  downward 
and  backward,  and  this  obliquity, 
which  varies  with  its  distention, 
will  correspond  to  a  line  extending 
from  between  the  umbilicus  and 
pubis  to  the  coccyx.  Its  divisions 
are  into  a  body  or  central  portion, 
an  upper  or  superior  fundus  ^  a  lower 
or  inferior  fundus  or  base,  and  a 
cervix  or  neck.  It  is  retained  in  its  position  by  ligaments, 
which  are  divided  into  the  false  and  the  true.  The  false  are 
formed  by  reflections  of  the  peritoneum,  and  are  two  poste- 
rior and  two  lateral.  TJie  posterior  extend  one  on  either 
side,  in  a  semilunar  form,  from  the  front  of  the  rectum  to 
the  back  part  of  the  bladder,  and  contain  the  obliterated 

FIG.  207  represents  the  Urinary  Bladder  and  its  appendages,  a  Muscular 
structure  of  the  Bladder,  b  b  Ureters,  c  c  Vasa  deferentia.  d  Vesiculae 
setninales.  /Efferent  duct  of  vesiculae  seminales.  g  Ductus  ejaculatorius.  h 
Prostate  gland,  i  Membranous  portion  of  urethra. 


URINARY  BLADDER.  645 

umbilical  arteries  and  ureters.  The  two  lateral  ligaments 
extend  from  the  iliac  fossae  to  the  sides  of  the  bladder,  and 
contain  the  vasa-deferentia  of  the  male,  and  the  round  liga- 
ments of  the  uterus  in  the  female. 

This  portion  of  the  peritoneum,  it  is  important  to  observe, 
descends  upon  the  front  and  the  sides  of  the  rectum,  to  about 
four  inches  from  the  anus,  leaving  consequently  the  lower 
portion  of  the  rectum  uncovered  by  peritoneum.  From 
this  point  it  is  reflected  forward  upon  the  bladder,  at  its 
lower  and  posterior  part,  a  short  distance  above  the  base  of 
the  prostate  gland,  and  about  the  middle  of  the  vesiculae 
seminales,  whence  it  passes  upward  upon  the  back  and 
sides  of  this  organ  to  its  superior  fundus,  and  is  then  traced 
onward  to  the  abdominal  muscles,  as  explained  elsewhere. 
It  is  just  below  the  line  of  reflection,  and  on  the  inferior 
fundus  of  the  bladder,  that  the  latter  organ  can  be  entered 
from  the  rectum  without  injuring  the  peritoneum. 

The  true  ligaments  are  two  anterior  and  two  lateral,  to 
which  are  added  the  two  obliterated  umbilical  arteries,  and 
the  urachuSj  making  seven  in  all. 

The  two  anterior  come  from  the  pelvic  fascia,  which  lines 
the  parietes  of  the  pelvis,  and  is  a  continuation  of  the  fascia 
iliaca.  They  commence  at  the  lower  portion  of  the  inner 
surface  of  the  pubis,  on  each  side  of  the  symphysis,  and 
proceed  upward  to  the  front  of  the  bladder,  upon  which 
they  expand,  as  well  as  upon  the  upper  surface  of  the  pros- 
tate. The  two  lateral  ligaments  are  also  continuations  of 
the  pelvic  fascia  from  the  levatores  ani  muscles  upon  the 
sides  of  the  bladder  and  prostate  gland.  The  umbilical 
ligaments  constitute  the  solid  fibrous  cords,  which  in  the 
foetus  were  the  hypogastric  arteries,  and  are  found  upon 
each  side  of  the  fundus  of  the  bladder  going  to  the  umbili- 
cus. The  urachus  is  attached  to  the  superior  extremity  of 
the  bladder,  and  goes  as  a  small  fibrous  cord  to  the  umbili- 
cus. In  the  fcetus  it  is  seen  as  a  tubular  canal,  though,  ac- 
cording to  Cruveilhier,  it  is  always  solid  in  both  foetus  and 
adult. 

Upon  the  external  surface  of  the  bladder,  six  regions 


646  URINARY  BLADDER. 

have  been  designated  by  anatomists :  1.  The  superior,  in 
contact  with  the  recti  muscles,  and  with  the  small  intes- 
tines, when  the  bladder  is  distended,  and  attached  to  which 
are  the  urachus  and  obliterated  umbilical  arteries  ;  2  and  3. 
The  lateral  regions,  corresponding  to  the  sides  of  the  pelvis  ; 
4.  The  posterior  region,  in  relation  with  the  rectum  in  the 
male,  and  the  uterus  in  the  female ;  5.  The  anterior  re- 
gion behind  the  pubis  and  recti  muscles,  deprived  of  the 
peritoneum ;  and  6.  The  inferior  region,  resting  upon  the 
vesiculae  seminales  and  prostate,  and  in  relation  with  the 
rectum  in  the  male,  and,  in  the  female,  contiguous  to  the 
vagina. 

Structure. — The  bladder  is  composed  of  four  coats,  the 
peritoneal,  muscular,  cellular,  and  mucous.  The  peritoneal 
or  serous  coat  is  only  partial,  covering  simply  the  posterior 
part  and  sides  of  the  bladder,  extending  from  the  summit 
to  within  an  inch  of  the  base  of  the  prostate,  whence  it  is 
reflected  upon  the  rectum,  forming  the  pouch  which  is  seen 
between  these  organs.  The  muscular  coat  is  arranged  into 
fasciculi  of  pale  fibres  running  in  various  directions,  hav- 
ing spaces  between  them  through  which  the  mucous  mem- 
brane sometimes  protrudes  so  as  to  form  pouches  in  which 
calculi  occasionally  lodge,  and  are  not  detected. 

The  muscular  fibres  are  seen  to  run  longitudinally  and 
circularly,  and  some  again  present  a  reticular  arrangement. 
The  longitudinal  are  regarded  as  the  most  numerous  and 
strongest.  They  commence  about  the  cervix  and  are  traced 
upward,  expanding  over  the  anterior  surface  of  the  bladder 
to  its  summit,  and  thence  descending  upon  the  posterior 
surface  and  sides,  back  to  the  neck,  where,  according  to 
Wilson,  they  are  inserted  into  a  ring  of  elastic  tissue,  as 
pointed  out  by  Sir  A.  Cooper  surrounding  the  beginning 
of  the  urethra,  and  into  the  isthmus  of  the  prostate.  The 
anterior  fibres  are  traced  into  the  pubes  and  rami  of  the 
ischia,  to  which  they  are  attached  by  four  tendons,  two  on 
each  side,  a  superior  and  inferior.  This  muscular  coat  re- 
ceives the  name  of  the  detrusor  urince. 

The  longitudinal  fibres  in  the  female,  according  to  Mr. 


URINARY  BLADDER. 

Harrison,  are  "  inserted  anteriorly  and  laterally  into  the 
cellulo-vascular  and  glandular  tissue  around  the  cervix, 
and  posteriorly  into  a  more  dense  tissue  connecting  the 
urethra  to  the  vagina." 

The  circular  fibres  are  found  to  be  scattered,  pale,  and 
indistinct  on  the  upper  portions  of  the  bladder,  while  on 
the  lower  and  about  the  neck  they  become  more  distinct 
and  close,  and  form  what  is  considered  by  some  a  distinct 
muscle,  called  the  sphincter  vesicce.  There  are  a  variety  of 
opinions  in  reference  to  this  sphincter  muscle ;  some,  with 
Mr.  Guthrie,  asserting  that  there  are  no  fibres  around  the 
neck  of  the  bladder  capable  of  forming  a  sphincter,  while 
others,  as  Mr.  Bell,  Harrison,  and  Homer,  distinctly  de- 
scribe them. 

Sir  Charles  Bell  represents  a  plane  of  muscular  fibres, 
forming  a  semicircular  band,  about  an  inch  in  breadth,  sur- 
rounding the  lower  half  of  the  orifice  of  the  urethra,  and 
at  this  point  especially  strong,  and  dispersing  into  the 
substance  of  the  bladder ;  while  the  upper  half  of  the  orifice 
is  surrounded  by  a  weaker  set  of  fibres,  though  continuous 
with  the  lower,  thus  completing  the  sphincter. 

Homer  speaks  of  a  similar  muscular  band  on  the  lower 
semi-circumference  of  the  neck  of  the  bladder,  the  fibres  of 
which,  however,  he  finds  not  to  run  into  the  ordinary  mus- 
cular structure  of  the  bladder,  but  to  go  transversely  and 
be  connected  with  the  lateral  lobes  of  the  prostate ;  while 
the  superior  semi-circumference  presents  a  broad,  thin, 
muscular  layer,  which  is  lost  in  the  muscular  structure  of 
the  bladder. 

Beneath  the  mucous  membrane  of  the  vesical  triangle, 
this  same  anatomist  describes  a  muscular  structure  of  the 
same  extent  and  shape  as  the  triangle  itself.  The  anterior 
angle  he  traces  to  the  posterior  part  of  the  caput  gallina- 
ginis.  Between  the  two  ureters,  says  Mr.  Harrison,  the 
circular  or  transverse  fibres  are  very  distinct,  and  a  semi- 
lunar  band  forms  the  base  of  the  trigone.  Muscular  fibres 
are  also  traced  around  and  upon  the  ureters. 

The  third  set  of  muscular  fibres,  from  their  honey-comb 


648  URINARY  BLADDER. 

appearance  and  the  various  directions  they  run,  are  called 
the  reticular.  Some  of  these  fasciculi  are  found  to  he  quite 
large,  and  from  their  projections  and  resemblance  to  the 
columnas  carneas,  have  heen  called  the  columnar  bladder- 
This  arrangement  produces  pouches  or  depressions  for  the 
lodgment  of  calculi. 

The  cellular  or  fibrous  coat  is  between  the  muscular  and 
the  mucous,  and  consists  of  fibres  very  compact,  dense, 
strong,  elastic,  extensible,  difficult  to  tear,  forming  a 
strong  bond  of  union  between  the  muscular  and  mucous 
coats,  and  impervious  to  water. 

The  fourth  coat  of  the  bladder  is  the  inner  or  mucous, 
called  also  the  villous  coat.  Its  color  is  rather  pale,  or  of 
a  reddish  white,  and,  in  the  contracted  state,  presents 
many  folds  or  wrinkles,  which  are  effaced  when  distended. 
It  abounds  with  small  mucous  follicles,  and  is  smoother 
than  the  same  membrane  in  the  stomach. 

Several  points  are  noticed  on  the  inner  surface  of  this 
coat.  First,  is  a  small  triangular  space,  below  and  behind 
the  neck  of  the  bladder,  known  as  the  vesical  triangle,  (tri- 
gone  vesical.)  This  space  forms  an  equilateral  triangle, 
about  an  inch  in  length,  included  between  the  orifice  of 
the  urethra  and  those  of  the  ureters.  The  openings  for  the 
ureters  form  the  posterior  angles,  while  that  of  the  urethra 
forms  the  anterior.  Mr.  Bell  traces  a  muscular  bundle  of 
fibres,  forming  the  lateral  margins  of  the  triangle,  and 
proceeding  from  the  ureters  to  the  mouth  of  the  urethra, 
designed  he  thinks  to  open  the  ureters  and  allow  the  free 
entrance  of  the  urine.  This  triangular  space  is  smooth, 
destitute  of  the  wrinkles  common  to  other  parts  of  the 
bladder,  and  is  very  vascular  and  sensitive.  By  the  aid  of 
the  lens  numerous  villi  are  detected. 

At  the  mouth  of  the  urethra,  or  anterior  angle  of  the 
trigone,  an  eminence  is  observed,  called  the  uvula  vesicce. 
This  is  situated  about  opposite  the  third  lobe  of  the  pros- 
tate, and  is  formed  by  a  projection  of  the  mucous  mem- 
brane, which  occasionally  becomes  an  obstacle  to  the  intro- 
duction of  the  catheter. 


MALE  ORGANS  OF  GENERATION.  649 

The  arteries  of  the  bladder  vary  in  their  origin,  number, 
and  size.  They  come  from  the  internal  iliac,  pudic,  and 
obturator. 

The  veins  form  around  the  cervix  a  plexus,  which  dis- 
charges into  the  internal  iliac  vein  or  some  of  its  branches. 

The  nerves  come  from  the  hypogastric  plexus,  consisting 
both  of  ganglionic  and  spinal  filaments,  which  explains 
the  fact  of  the  bladder  being  both  a  voluntary  and  in- 
voluntary organ. 

Function. — The  use  of  the  bladder  is  essentially  that  of  a 
reservoir  for  the  urine  ;  and  by  its  muscular  apparatus  it  is 
the  chief  agent  of  expelling  the  urine,  as  in  paralysis  of 
the  bladder  no  action  of  the  abdominal  muscles  can  effect 
the  expulsion. 


CHAPTER  VI. 

THE  ORGANS  OF  THE  TRUNK. 

FIFTH     DIVISION. 

ORGANS    OF   THE   PELVIS. 

THIS  division  comprises  the  organs  of  the  pelvis,  including 
the  male  and.  female  organs  of  generation. 

SECTION    I. 
THE  MALE   ORGANS   OF   GENERATION. 

These  organs  comprise  the  testes,  and  their  appendages, 
the  vasa  deferentia,  the  vesiculce  seminales,  the  prostate 
gland,  and  the  penis. 

The  testes  are  two  oval  glands,  suspended  rather  obliquely 
and  having  the  sides  compressed.  The  right  is  higher  than 
the  left.  Each  is  surrounded  by  several  coats,  the  scrotum, 
tunica  vaginalis,  tunica  albuginea,  and  tunica  vasculosa. 

The  scrotum  is  a  double  membrane.  The  outer  consists  of 
the  common  integument,  and  is  distinguished  by  being  very 
thin,  of  a  dark  color,  and  so  transparent  that  the  subcu- 


650  THE  TESTES. 

taneous  veins  and  follicles  are  seen  through  it.    Hairs,  run- 
ning obliquely,  thinly  cover  it,  and  it  is  usually  wrinkled. 
FIG.  208.          This  coat  is  common  to  both  testes,  and  is 
divided  into  two  lateral  portions  by  a  me- 
dian line  common  to  the  perineum  and 
under  surface  of  the  penis,  called  the  raplie. 
The  next  coat,  or  proper  coat  of  the  scro- 
tum, is  the  dartos. 

The  dartos  is  a  peculiar  membrane,  be- 
ing regarded  as  a  structure  between  the 
cellular  and  muscular,  and  consisting  of 
a  contractile  fibrous  tissue.  It  is  attached 
to  the  rami  of  the  pubes  and  ischium,  and 
along  the  mesial  line,  where  it  is  found  most  dense  ;  it  is 
reflected  upward  between  the  testes,  constituting  the  sep- 
tum scroti.  It  presents  a  reddish  appearance,  from  the 
quantity  of  blood-vessels  present ;  is  always  destitute  of  fat, 
and  has  its  fibres  running  in  every  direction,  though  but 
loosely  connected  together.  Its  powers  of  contraction  are 
well  marked,  as  seen  in  the  corrugation  of  the  skin  from 
the  application  of  cold,  and  hence  by  some  it  is  considered 
muscular. 

The  dartos,  by  some  anatomists,  is  regarded  as  an  expan- 
sion of  the  gubernaculum  testis;  but  as  it  is  found  in  the 
integument  of  the  scrotum  before  the  descent  of  the  testes, 
it  is  justly  considered  by  others  as  entirely  independent  of 
this  structure.  Beneath  the  dartos  are  the  fibres  of  the 
cremaster  muscle,  which  gives  but  a  partial  covering  to  the 
testicle,  and  receives  the  name  of  tunica  erytliroides. 

Next  in  order  is  a  condensed  cellular  membrane,  which 
surrounds  each  testicle  and  its  chord,  connecting  the  cre- 
master and  dartos  with  the  tunica  vaginalis,  and  called  the 
tunica  vaginalis  communis. 

The  tunica  vaginalis  is  a  serous  membrane,  derived  from 

FIG.  208  represents  a  transverse  section  of  the  Testicle,  a  Cavity  of  the 
tunica  vaginalis  testis.  6  Tunica  albuginea.  c  Corpus  Highmorianum.  d  Tu- 
nica vasculosa.  e  One  of  the  lobules  with  its  seminal  tubes.  /  Section  of 
epididymus. 


THE    TESTES.  651 

the  peritoneum,  during  the  descent  of  the  testes  from  the  ab- 
domen into  the  scrotum.  After  the  descent  of  the  testes  into 
the  scrotum,  the  canal  for  its  passage  hecomes  closed,  and 
this,  like  all  serous  membranes,  presents  the  form  of  a  shut 
sac.  One  portion  of  it  lines  the  inner  surface  of  the  dartos, 
and  is  called  the  parietal ;  the  other  is  reflected  upon  the 
forepart  and  sides  of  the  testicle,  and  is  the  visceral  or 
tunica  vaginalis  testis.  Between  the  two  portions  is  the 
smooth  surface  and  cavity  in  which  the  secretion  occurs. 
This  membrane  is  loosely  attached  to  the  scrotum  and  epi- 
didymis,  but  firmly  to  the  testis,  or  rather  to  the  next 
membrane,  the  tunica  albuginea. 

The  tunica  albuginea  forms  the  proper  coat  of  the  testis, 
is  in  direct  contact  with  the  gland,  consists  of  a  dense 
fibrous  structure,  of  a  bluish  white  color,  and  serves  to 
preserve  the  organ  in  its  proper  shape.  From  its  union 
with  the  tunica  vaginalis,  it  is  called  a  fibro-serous  mem- 
brane, such  as  the  pericardium  and  dura  mater.  After 
investing  the  testis,  it  is  inflected  at  the  posterior  part, 
into  the  interior  of  the  gland,  by  a  vertical  partition  con- 
eisting  of  two  laminse,  called  the  mediastinum  testis,  or 
corpus  Higlimorianum,  between  which  are  found  the  vessels, 
nerves,  and  ducts.  Fibrous  cords  radiate,  in  great  num- 
bers, from  this  mediastinum  to  the  inner  surface  of  the 
tunic,  and  are  called  trabeculce  septulce. 

The  tunica  vasculosa,  so  named  by  Sir  Astley  Cooper, 
lines  the  interior  of  the  albuginea,  and  is  regarded  as  the 
nutrient  membrane  of  the  testis,  bearing  the  same  relation 
to  the  latter,  that  the  pia-mater  does  to  the  brain.  It  is  a 
very  delicate  membrane,  consisting  of  a  cellular  web,  con- 
taining the  minute  ramifications  of  the  spermatic  vessels, 
dipping  into  the  substance  of  the  gland,  and  sending  pro- 
cesses between  the  several  lobules. 

On  dividing  the  tunica  albuginea,  the  proper  substance 
of  the  gland  is  seen  presenting  a  soft,  grayish,  or  yellowish 
appearance,  consisting  of  numerous  delicate  threads,  loosely 
connected  together,  and  which  may  be  drawn  out,  for  two 
or  more  feet,  without  breaking.  These  are  the  tubuli  semini- 


652 


THE   TESTES. 


Fie.  209. 


feri,  and  are  in  coils  or  convolutions.  Being  collected  in 
bundles  or  fasciculi,  they  are  termed  lobules,  of  which  lat- 
ter there  are  estimated  between  three  and  four  hundred, 
having  a  length,  according  to  Dr.  Monroe,  of  about  5208 
feet.  The  diameter  of  each  tube  is  made  to  measure  from 
the  1-200  to  the  1-150  part  of  an  inch,  and  the  length  of 
each  about  1*7  feet.  Their  commencement  is  either  in  loops 
of  anastomosis  or  ccecal  terminations,  which  communicate, 
though  the  tubes  of  one  lobule  are  said  not  to  inosculate 
directly  with  those  of  another. 

The  lobules  present  a  conical  form,  having  their  bases 
towards  the  surface,  and  their  apices  towards  the  mediasti- 
num testis,  consisting  of  one  or  many  convoluted  tubuli 
seminiferi,  and  are  enclosed  and  separated  by  processes  from 
the  tunica  albuginea  and  vasculosa.  The  tubuli  seminiferi 
of  the  lobules  coalesce  in  about  twenty 
or  thirty  straight  tubes,  called  vasa 
recta,  which,  entering  the  mediastinum 
and  interlacing  here  with  each  other 
and  with  the  vessels  and  nerves  of  the 
gland,  receive  the  name  of  rete  testis. 
The  rete  testis  is  situated  at  the  poste- 
rior part  of  the  gland,  and,  at  its  upper 
part,  passes  through  the  tunica  albugi- 
nea, by  from  ten  to  thirty  tubes,  called 
vasa  efferentia,  each  of  which,  becoming 
convoluted,  receives  the  name  of  conus 
vasculosus.  From  the  bases  of  these 
coni  vasculosi,  larger  tubes  are  formed, 
constituting  the  epididymis. 

The  epididymis  is  situated  upon  the 
outside  of  the  tunica  albuginea,  upon  the  back  of  the  testis, 
being  connected  to  the  latter  by  the  reflected  tunica  vagin- 
alis,  and  taking  a  vertical  direction.  It  is  formed  of  the 

FIG.  209  represents  the  minute  structure  of  the  Testicle.  1  1  Tunica  albu- 
ginea. 2  2  Corpus  Highmorianum.  33  Tubuli  seminiferi.  44  Vasa  recta. 
5  Rete  testis.  6  Vasa-efFerentia.  7  Coni-vasculosi,  or  globus  major.  8  Epi- 
didymis. 9  Globus  minor.  10  Vas-deferens.  11  Vasculum  aberrans. 


THE  TESTES.  653 

convoluted  coni  vasculosi,  presenting  an  arched  form,  the 
larger  end  of  which  is  above,  and  called  the  globus  major; 
the  lower  end  is  the  globus  minor,  while  the  intermediate 
portion  constitutes  the  body. 

The  epididymis  can  be  unraveled  into  a  single  conro- 
luted  tube,  having  an  estimated  measure  of  twenty-one 
feet,  and  receiving  at  intervals  of  about  three  inches  the 
coni  vasculosi.  At  the  lower  part  of  the  epididymis  this 
tube  is  less  convoluted,  and  ends  in  the  vas  defer  ens,  the 
excretory  duct  of  the  testicle. 

The  vas  deferens  is  a  large  tube  of  cartilaginous  density, 
proceeding  from  the  globus  minor  to  the  vesiculae  semi- 
nales,  and  designed  to  conduct  the  semen  into  the  latter 
from  the  testis.  It  ascends  parallel  with  the  epididymis, 
and  above  the  head  of  the  latter  becomes  one  of  the  con- 
stituents of  the  spermatic  cord,  along  the  back  part  of 
which  it  ascends  to  the  internal  abdominal  ring ;  here  it 
leaves  the  vessels  of  the  cord,  and  dipping  into  the  pelvis, 
is  enclosed  in  the  lateral  fold  of  the  peritoneum,  along 
which  it  proceeds  to  the  side  and  inferior  fundus  of  the 
bladder,  where  it  converges  towards  its  fellow  on  the  in- 
side of  the  vesictilae  seminales,  at  the  angle  of  their  junc- 
tion, and  at  the  base  of  the  prostate  each  vas  deferens  joins 
the  corresponding  duct  of  the  vesiculas  seminalis,  forming 
the  ductus  ejaculatorius ,  which  passes  through  the  prostate, 
and  opens  into  the  urethra  near  the  neck  of  the  bladder 
on  the  side  of  the  caput  gallinaginis. 

The  vas  deferens  consists  of  two  coats,  an  external, 
which  is  thick,  hard,  and  firm,  and  regarded  as  fibrous ; 
the  internal  is  thin,  pale,  and  mucous. 

Just  before  the  commencement  of  the  vas  deferens,  a 
second  tube  is  seen  to  leave  the  epididymis  and  run  for  a 
short  distance  parallel  with  the  vas  deferens,  which  it 
either  joins  or  ends  in  a  cul-de-sac.  It  is  called  vasculum 
aberrans  (or  blind  duct)  of  Holler. 

The  spermatic  cord  consists  of  the  vas  deferens  just  de- 
scribed, the  spermatic  artery  and  veins,  nerves,  and  lymph- 
atics covered  by  cellular  membrane,  and  the  cremaster 


654  THE  TESTES. 

muscle.  It  extends  from  the  epididymis  to  the  internal 
abdominal  ring,  and  is  covered  by  the  remains  of  the  peri- 
toneum, which  accompanied  the  descent  of  the  testis,  called 
the  tunica-vaginalis  of  the  cord. 

The  spermatic  artery  comes  from  the  abdominal  aorta, 
Bometimes  from  the  renal  artery,  proceeds  along  the  psoas 
muscle  to  the  internal  abdominal  ring ;  here  it  joins  the 
spermatic  cord,  and  descends  along  with  it  to  the  back 
part  of  the  testicle,  where  it  enters  the  rete  testis  by  divid- 
ing into  several  branches,  which  again  subdivide  very 
minutely  around  the  tubuli  seminiferi.  A  branch  goes  to 
the  vas  deferens  from  the  superior  vesical  called  deferential, 
and  one  to  the  creinaster  muscle  from  the  epigastric,  the 
cremasteric  artery. 

The  veins,  on  leaving  the  rete  testis,  become  very  tortu- 
ous, twine  round  the  arteries  and  form  a  plexus  called  the 
corpus  pampiniforme,  constituting  the  principal  bulk  of  the 
cord.  The  right  spermatic  vein  ends  in  the  inferior  cava 
near  the  renal.  The  left  ends  in  the  left  renal  vein. 

The  nerves  come  from  the  spermatic  plexus.  Branches 
also  from  the  lumbar  plexus  go  to  the  cremaster. 

The  lymphatics  go  to  the  lumbar  glands. 

The  testes  are  not  seen  first  in  the  scrotum,  but  are  situ- 
ated in  the  abdominal  cavity,  immediately  beneath  the 
kidneys  and  behind  the  peritoneum.  They  are  represented 
as  being  about  two  lines  long  in  the  middle  of  the  third 
month  of  uterine  life.  About  the  fifth  or  sixth  month  they 
have  descended  as  low  as  the  inferior  portion  of  the  psoas 
muscles.  In  the  seventh  month  they  are  seen  in  the  iliac 
fossa ;  in  the  eighth  in  the  abdominal  canal ;  and  a  few 
weeks  before  birth  they  are  found  to  reach  the  scrotum. 
The  gubernaculum  testis  is  a  cord  composed  of  cellular  and 
ligamentous  fibres,  extending  from  the  inferior  portion  of 
the  testicle  to  the  scrotum,  and  is  regarded  as  the  agent 
by  the  contractile  power  of  which  the  testis  descends  or  is 
drawn  into  the  scrotum. 

function  of  the  Testes. — The  office  of  these  glands  has 
been  already  stated  to  be  to  secrete  the  semen,  a  fluid 


VESICUL.E  SEMINALES.  655 

which,  according  to  the  microscope,  contains  numerous 
little  filamentary  bodies  termed  spermatozoa  or  seminal 
animalcules ,  and  granules,  which  constitute  the  elements 
of  the  reproductive  cells,  by  which  the  germs  for  the  con- 
tinuance of  the  human  species  are  provided. 

The  Vesiculw  Seminales}  (Fig.  207.)  These  bodies  are 
two  in  number,  and  situated  on  the  under  surface  of  the 
bladder  behind  and  above  the  prostate,  and  in  front  of  the 
rectum.  They  diverge  behind,  and  converge  in  front,  where 
they  are  separated  only  by  the  vasa  deferentia.  They  are 
attached  to  the  bladder  by  cellular  tissue,  and  are  sur- 
rounded by  a  venous  plexus.  The  form  of  each  is  oval, 
having  a  length  of  about  two  inches,  and  a  breadth  of  half 
an  inch.  They  present  the  appearance  of  cells,  but  are 
found  to  consist  of  one  continuous  convoluted  tube,  the  sev- 
eral coils  communicating,  and  being  connected  by  cellular 
tissue.  Each  vesicula  has  two  coats,  an  external  of  fibro- 
cellular  substance,  and  an  internal  or  mucous.  Each  vesicle 
has  an  excretory  duct  about  a  line  and  a  half  long,  which, 
uniting  in  the  substance  of  the  prostate  with  the  vas 
deferens,  forms  a  common  duct,  the  ductus  ejaculatorius , 
which  is  about  three  quarters  of  an  inch  long,  passing  for- 
ward through  the  prostate,  and  opening  into  the  urethra 
on  the  anterior  edge  of  the  caput  gallinaginis.  These 
bodies  communicate  freely  with  the  vas  deferens,  and  are 
considered  as  reservoirs  for  the  semen,  but  they  are  found 
also  to  contain  a  fluid  of  their  own  secretion,  consisting  of 
mucus  of  a  yellowish  brown  color  and  viscid  consistence. 

Prostate  Gland,  (Fig.  207.) — This  body  is  situated  upon 
the  neck  of  the  bladder,  and  about  an  inch  on  the  urethra. 
In  shape  and  size  it  resembles  a  horse-chestnut.  It 
is  behind  the  triangular  ligament,  and  in  front  of  the 
rectum,  to  which  it  is  attached  by  cellular  structure. 
Its  base  looks  backward,  and  its  apex  forward  towards 
the  urethra.  It  is  about  an  inch  in  length,  and  half 
an  inch  in  thickness.  It  is  fixed  by  the  anterior  liga- 
ments of  the  bladder  to  the  symphysis  of  the  pubis,  and 
by  the  posterior  layer  of  the  triangular  ligament,  consti- 


656  THE  PENIS. 

tuting  a  strong  fascia,  which  invests  the  sides  and  infe- 
rior surface  of  this  gland,  thus  forming  for  it  a  capsule. 
Its  density  is  firm  and  resisting.  Its  color  is  of  a  grayish 
hue.  The  posterior  surface  is  flat  and  notched,  which 
divides  it  into  two  lateral  lohes,  and  on  raising  the  vesicu- 
las  seminales,  a  transverse  process  is  ohserved  connecting 
the  lateral  lobes,  called  hy  Sir  Everard  Home  the  third 
or  middle  lobe  of  the  prostate.  The  sides  of  the  prostate 
are  round,  smooth,  and  covered  by  the  levatores  ani  mus- 
cles, veins,  and  a  strong  fascia.  The  structure  of  this  gland 
consists  of  mucous  follicles,  which  discharge  by  ten  or 
more  excretory  ducts  into  the  urethra  on  either  side  of  the 
caput  gallinaginis,  and  these  follicles  are  surrounded  by  a 
condensed  fibrous  or  cellular  tissue.  The  fluid  of  this 
gland  is  white  or  brownish,  and  viscid. 

THE  PENIS. 

The  penis  is  connected  to  the  symphysis  pubis,  and  in 
front  of  it.  It  is  divided  into  a  root,  body,  and  extremity. 
The  root  is  attached  by  two  crura  to  the  rami  of  the  is- 
chium  and  pubis.  The  body  forms  the  intermediate  or  cen- 
tral portion,  while  the  extremity  consists  of  the  glans  penis. 

Structure. — The  penis  consists  of  integument,  cellular 
tissue,  the  corpora  cavernosa,  corpus  spongiosum,  and  ure- 
thra. 

The  integument  is  delicate,  thin,  loose,  and  free  from 
fat.  It  projects  beyond  the  extremity  of  the  glans,  so  as  to 
form  a  loose  sheath  termed  the  prepuce.  It  is  then  re- 
flected back  to  the  root  of  the  glans,  thence  over  the  glans 
itself,  where  it  is  very  delicate,  and  is  traced  to  the  open- 
ing of  the  urethra  continuous  with  the  lining  membrane 
of  this  canal.  The  prepuce  is  connected  to  the  glans  by  a 
longitudinal  fold  or  process  called  frenum  preputii.  Its  in- 
ner layer  is  mucous  and  is  connected  to  the  outer  by  loose 
cellular  tissue,  which  readily  allows  the  infiltration  of  se- 
rum. Around  the  corona  of  the  glans,  and  beneath  the 
skin,  numerous  sebaceous  glands  are  seen,  called  glandulce 
odoriferce  or  glands  of  Tyson. 


THE   PENIS. 


65T 


The  cellular  coat  is  occasionally  found  much  condensed, 
and  lost  in  the  fascia  of  the  thighs.  It  is  described  as  being 
reflected  from  the  linea  alba,  upon  FIG.  210. 

the  penis,  as  far  as  its  extremity, 
being  particularly  strong  where 
the  penis  is  connected  with  the 
pubis,  and  constituting  its  sus~[ 
pensory  ligament.     This  ligament1 
consists  of  dense,  fibrous  tissue,  in 
which  elastic  fibres  have  been  de- 
tected, and  it  is  supposed  some  mus- 
cular fibres  have  also  been  seen. 

The  corpora  cavernosa  form  the 
largest  portion  of  the  penis,  and 
consist  of  two  semi-cylindrical 
bodies  of  considerable  length, 
placed  side  by  side,  and  having  a 
partition  between  them,  though 
rather  imperfect,  termed  septum 
pectiniforme.  The  corpora  caver- 
nosa arise  by  two  conical  crura 
from  the  rami  of  the  ischia  and 
pubis,  beginning  in  front  of  the 
tuber  ischii,  and  proceeding  to 
the  lower  part  of  the  symphysis, 
where  they  unite  to  form  the 
body ;  upon  the  extremity  of 
which  is  situated  the  glans  penis.  The  two  corpora,  rep- 
resenting two  cylinders  placed  side  by  side,  present  be- 

FIG.  210  represents  the  Penis  and  Bladder  laid  open.  1  1  Bladder.  2  2 
Ureters.  3  3  Vesical  orifices.  4  Uvula  vesicae.  5  Superior  (Vndus  of  blad- 
der. 6  Bas-fond  of  bladder.  7  Centre  of  vesicle  triangle  8  Caput  gallina- 
ginis  or  verumontanum.  9  Opening  of  the  ductus  ejaculatorius  10  Depressiom 
near  the  caput.  11  Ducts  from  prostate  gland.  12  13  Lateral  lobes  of  th« 
prostate.  14  Urethra,  its  prostatic  portion.  15  Membranous  portion.  10 
Cowper's  glands.  17  Point  of  entrance  of  their  excretory  ducts.  18  Bulb  of 
urethra  laid  open  19  Section  of  corpora  cavernosa.  20  Glans  penis  divided. 
21  Prepuce  taken  off.  22  Internal  portion  of  urethra  laid  open.  23  Exterior 
portion  of  corpora  cavernosa.  2425  Accelerator-urinae  muscle.  2627ErecU*. 
penis. 

42 


658  THE  PENIS. 

tween  them  two  grooves,  the  one  superior,  occupied  "by 
the  dorsal  vessels  and  nerves ;  the  other,  inferior,  contain- 
ing the  urethra.  Each  corpus  consists  of  a  white,  very 
strong,  fibrous,  and  elastic  membrane,  consisting  mostly  of 
longitudinal  fasciculi  closely  interlacing  each  other,  though 
an  internal  layer  of  circular  fibres,  as  continuous  with  the 
septum,  is  also  seen.  From  the  inferior  groove,  a  number 
of  radiating  fibrous  bands  are  seen  crossing  the  cavities  of 
the  corpora  to  be  inserted  in  the  inner  walls  of  this  fibrous 
tunic ;  these  cords  are  called  trabeculce,  and  are  believed  to 
strengthen  the  organ  as  well  as  to  limit  its  distension.  The 
interior  of  each  corpus  is  occupied  by  a  soft,  cellulo-vascu- 
lar,  or  erectile  tissue,  presenting  a  spongy  appearance,  or  a 
multitude  of  cells,  all  of  which  communicate  freely  with 
each  other  and  with  the  veins,  and  consist,  says  Dr.  Morton, 
of  an  intertexture  of  veins  closely  woven  together,  so  as  to 
present  the  appearance  of  cells,  which  veins  or  venous  plex- 
uses are  supported  and  separated  by  the  trabeculse. 

The  corpus  spongiosum  surrounds  the  urethra,  and  ex- 
extends  from  between  the  crura  about  an  inch  behind 
their  junction  to  the  extremity  of  the  penis.  Its  poste- 
rior extremity  is  called  the  bulb — its  anterior  the  glans 
penis.  The  base  of  the  glans  presents  a  projection  or 
shoulder,  termed  the  corona  glandis,  and  behind  this  is 
noticed  a  contraction  called  the  neck. 

The  structure  of  the  corpus  spongiosum  resembles  the 
cavernosum,  except  that  its  external  aponeurotic  coat  is 
much  thinner,  and  its  interior  spongy  erectile  tissue  much 
finer  and  more  delicate.  There  is  no  direct  communication 
between  the  corpora  cavernosa  and  spongiosum,  though  a 
fine  injection  from  the  pudic  artery  will  occasionally  suc- 
ceed in  injecting  both  at  the  same  time. 

The  urethra  (Fig.  210)  is  a  membranous  canal  situated 
along  the  inferior  groove  of  the  corpora  cavernosa,  and  ex- 
tending from  the  neck  of  the  bladder  to  the  extremity  of 
the  penis.  The  course  of  this  canal  from  the  neck  of  the 
"bladder  is  first  forward  and  downward,  covered  by  the 
prostate  gland,  and  called  the  prostatic  portion.  It  then 


THE  PENIS.  659 

proceeds  to  the  symphysis  pubis,  beneath  which  it  makei 
a  slight  curve,  having  the  concavity  upward. 

This  portion  is  called  the  membranous,  while  the  balance, 
commencing  at  the  bulb  and  going  to  the  extremity  of  the 
glans,  receives  the  name  of  the  spongy  portion. 

The  length  of  the  urethra  varies  according  to  the  erection 
of  the  penis,  averaging  from  seven  to  nine  inches.  To  the 
prostatic  portion  is  given  about  an  inch  and  a  half,  and  to 
the  membranous  about  an  inch.  The  urethra  is  composed 
of  two  coats,  an  outer  fibrous  and  elastic,  and  varying  in 
strength  and  density  at  different  points,  being  stronger  in 
the  prostatic  and  membranous  portions  than  in  the  spongy; 
and  the  inner  or  mucous  coat  which  is  smooth  and  thin, 
and  continuous  with  the  mucous  coat  of  the  bladder  poste- 
tiorly,  and  the  integument  of  the  glans  anteriorly,  also 
with  the  lining  membrane  of  the  excretory  ducts  of  Cow- 
per's  glands,  the  prostate,  the  ejaculatory  ducts,  and  the 
several  lacunae. 

The  prostatic  portion  is  considered  the  widest  part  of  the 
canal ;  on  its  lower  surface  the  mucous  coat  presents  a  lon- 
gitudinal fold  along  the  mesial  line,  called  caput  gallinagi- 
nis  or  verumontanum.  On  each  side  of  the  caput  gallinaginis 
a  fossa  is  seen,  called  prostatic  sinus,  in  which  the  ducts  of 
the  prostate  open.  At  the  anterior  extremity  of  the  caput 
the  common  ejaculatory  ducts  are  found  to  terminate,  and 
between  the  latter,  an  opening  looking  backward  into  a 
small  dilated  sac,  is  noticed,  called  sinus  pocularis.  The 
caput  gallinaginis  is  regarded  in  the  light  of  a  valve  to 
prevent  the  escape  of  urine  in  the  contracted  state  of  the 
urethra ;  but  during  the  action  of  the  detrusor  urinse,  the 
caput  is  drawn  down  and  the  elastic  ring  expanded  so  as 
to  permit  the  escape  of  the  urine.  The  membranous  portion, 
is  the  narrowest  part  of  the  canal,  and  is  surrounded  by  an 
elastic  and  erectile  reddish  tissue,  and  the  deep  layer  of  the 
triangular  ligament,with  the  compressores  urethrae  muscles 
It  lies  between  the  prostate  and  bulb.  In  the  latter  the 
urethra  again  enlarges,  and  then  again  in  the  spongy  por- 
tion, which  is  the  longest  of  the  three,  becomes  smaller  till 


660  THE  PENIS. 

it  approaches  the  glans,  where  it  becomes  so  large  as  to 
receive  the  name  of  fossa  navicularis.  The  mucous  coat  is 
very  sensitive,  and  so  numerous  and  superficial  are  its  veins, 
as  to  bleed  freely,  often,  on  introducing  the  catheter.  The 
urethra  abounds  with  mucous  lacunae,  especially  upon  its 
upper  wall,  which  discharge  their  secretions  into  this  canal ; 
their  orifices  present  forward,  and  are  believed  sometimes 
to  interrupt  the  course  of  the  catheter.  One  of  these,  about  an 
inch  and  a  half,  from  the  meatus  is  named  the  lacuna  magna. 

Cowper's  Glands. — These  are  two  bodies  about  the  size  of 
peas  situated  behind  the  bulb,  and  covered  by  the  accelera- 
tores  urinae  muscles.  They  are  of  a  yellowish  color,  hard, 
and  sometimes  not  found.  They  each  discharge  into  the 
urethra  in  front  of  the  bulb  by  an  excretory  duct  which 
runs  forward  for  about  an  inch. 

The  arteries  of  the* penis  come  from  the  terminal  branches 
of  the  internal  pudic.  The  internal  pudic  arises  from  the 
internal  iliac,  forming  one  of  its  terminating  branches  ; 
sometimes  it  comes  from  the  ischiatic,  along  with  which  it 
leaves  the  pelvis  below  the  pyriform  muscle,  returns  again 
between  the  sacro-sciatic  ligaments,  and  then  ascends  along 
the  inner  side  of  the  tuber  and  ramus  of  the  ischium  and 
pubis,  to  a  short  distance  below  the  symphysis,  wheie  it  ends 
in  two  branches.  In  this  course,  besides  supplying  branches 
to  the  bladder,  rectum,  vesiculse  seminales,  prostate,  and  to 
the  vagina  in  the  female,  it  sends  off  opposite  the  ramua 
of  the  ischium  the  artery  of  the  bulb,  which  passes  between 
the  triangular  ligament,  and  is  distributed  through  the 
corpus  spongiosum  as  far  as  the  glans. 

The  terminating  branches  of  the  internal  pudic  are  the 
arteria  dorsalis  penis  and  arteria  corporis  cavernosi.  The 
former  goes  between  the  crura  upon  the  dorsum  of  the 
penis  as  far  as  the  prepuce,  which  it  supplies,  also  forming 
a  circle  around  the  corona  glandis,  and  anastomosing  with 
branches  in  the  glans  of  the  corpus  spongiosum.  The 
artery  of  the  corpus  cavernosum  enters  the  crus,  and  runs 
along  the  septum,  giving  oif  branches  as  it  proceeds. 

Muller  speaks  of  arteries  which  he  calls  arterice  helecince, 


FEMALE  ORGANS  OF  GENERATION.          661 

coming  off  from  the  pudic,  and  going  to  the  venous  cells 
in  tufts.  The  existence  of  these,  however,  is  denied  b7 
other  anatomists. 

The  veins  are  numerous  and  large,  and  supplied  with 
valves.  They  are  divided  into  the  superficial  and  deep. 
The  former  begin  in  the  prepuce,  form  the  two  dorsal  veins 
of  the  penis,  which  go  to  the  root  of  the  penis,  receiving 
branches  in  their  course,  and  then  pass  beneath  the  arch 
of  the  pubis  to  join  the  plexuses  of  the  bladder  and  pros- 
tate gland.  The  deep  veins  accompany  the  pudic  artery 
and  its  branches,  and  join  the  internal  iliac. 

The  nerves  of  the  penis  come  from  the  internal  pudic, 
which  has  its  origin  from  the  lower  part  of  the  sacral 
plexus.  The  internal  pudic  nerve  takes  a  similar  course 
with  the  internal  pudic  artery,  along  the  inner  surface  of 
the  tuber  and  ramus  of  the  ischium,  covered  by  the  obtu- 
rator fascia,  and  towards  the  pubis  it  divides  into  a  supe- 
rior and  inferior  branch.  The  superior  nerve  accompanies 
the  arteria  dorsalis  to  the  glans  of  the  penis,  which  it  sup- 
plies. It  sends  off  at  the  root  of  the  penis  a  branch  which 
enters  the  corpus  cavernosum,  also  a  cutaneous  branch, 
supplying  the  integument  and  prepuce.  The  dorsal  nerve 
in  the  glands  of  the  penis  is  observed  to  expand,  and  as- 
sume a  reddish,  ganglionic  appearance,  sending  off  delicate 
filaments,  which  are  traced  to  the  very  sensitive  membrane 
covering  the  glans. 

The  inferior  branch  of  the  pudic  supplies  the  bulb  and 
corpus  spongiosum,  the  scrotum,  muscles  and  integuments 
of  the  perineum,  and  the  anus.  Branches  of  the  sympa- 
thetic are  also  traced  to  the  penis. 

SECTION    II. 

THE  FEMALE  ORGANS  OF  GENERATION. 

These  comprise  the  external  and  the  internal  organs  of 
generation. 

The  external  organs  of  generation  include  the 
Mons  veneris,    Labia  majora,  Labia  minora, 

Clitoris,  Meatus  urinarius,     Orifice  of  the  vagina. 


662  THE  VULVA. 

The  term  vulva  is  applied,  by  some  anatomists,  to  all 
these  parts;  while  others  restrict  this  term  simply  to 
the  fissure  or  urino-sexual  opening  between  the  labia 
major  a. 

The  mons  veneris  is  the  prominence  situated  on  the  front 
and  upper  part  of  the  pubis.  It  is  composed  chiefly  of  cel- 
lular tissue,  abounding  with  adipose  matter,  and,  in  the 
adult,  is  covered  with  hair. 

The  labia  majora,  or  externa,  are  two  longitudinal  folds 
of  integument,  situated  upon  either  side,  and  extending 
from  the  rnons  veneris  in  front,  to  their  common  junction 
behind,  in  a  crescentic  edge  or  commissure  called  the  four- 
chette.  Between  this  latter  and  the  vagina  a  depression  is 
observed,  termed  the  fossa  navicularis. 

Between  the  fourchette  and  the  anus,  a  distance  of  about 
an  inch,  is  the  perineum.  The  labia,  like  the  mons  veneris, 
consist  of  loose  cellular  tissue  and  fatty  matter,  and  consti- 
tute the  anterior  boundary  of  the  sexual  organs.  The 
external  surface  is  covered  with  hair,  the  internal  is  a 
mucous  membrane,  covered  with  a  smooth,  delicate  epi- 
thelium, and  containing  numerous  sebaceous  follicles.  The 
use  of  these  labia  seems  to  be,  to  favor  the  expulsion  of  the 
child,  as  during  parturition  they  are  found  completely 
unfolded. 

The  labia  minora,  or  interna,  called  also  nymplice,  are 
situated  within  the  greater  labia,  and  consist  of  two  smaller 
folds  of  mucous  membrane,  which  descend  and  are  lost 
upon  each  side  of  the  vaginal  orifice.  They  are  also  cov- 
ered by  a  fine  epithelium,  have  many  sebaceous  follicles, 
and  enclose  an  erectile  tissue.  They  are  broad  before, 
narrow  behind,  proportionally  more  developed  than  the 
greater  labia  in  the  infant,  and  sometimes  found  very 
much  enlarged  and  elongated  from  hypertrophy.  In  par- 
turition they  are  also  unfolded,  and  disappear. 

The  clitoris  is  situated  directly  below  the  symphysis  pubis, 
and  is  compared  to  the  male  penis.  It  presents  a  small  red 
prominence,  constituting  a  body,  which  is  formed  by  the 
union  of  the  crura,  arising  from  the  rarni  of  the  pubis  and 


THE  URETHRA. 

ischium,  and  joining  opposite  the  symphysis ;  to  which  they 
are  connected  by  a  suspensory  ligament.  The  body  is  from 
half  an  inch  to  an  inch  long,  rather  curved,  looks  down- 
ward from  between  the  anterior  commissure  of  the  labia, 
and  from  having  some  resemblance  in  its  extremity  to  the 
glans  penis,  is  called  the  glans  ditoridis.  The  clitoris  is 
covered  by  a  fold  of  the  mucous  membrane,  derived  from 
the  upper  part  of  the  nympha?,  and  called  prceputium  dito- 
ridis. In  structure  the  clitoris  resembles  the  corpora  caver- 
nosa  penis,  in  having  an  exterior  fibrous  sheath,  and  an 
interior  spongy,  erectile  tissue.  It  is  also  supplied  in  pretty 
much  the  same  manner  with  blood-vessels  and  nerves,  as 
the  penis,  but,  unlike  the  latter,  is  imperforate,  and  not 
concerned  in  conducting  the  urine  from  the  bladder.  There 
is  also  an  erector  muscle  to  this  body,  like  the  erector  penis, 
which  will  be  described  under  the  head  of  perineum.  The 
clitoris,  like  the  nymplise,  is  large  in  the  infant,  and  has 
been  seen  elongated  to  the  extent  of  one  or  two  inches. 

The  meatus  urinarius  is  situated  about  an  inch  below  the 
clitoris,  immediately  above  the  vagina,  and  is  always  readily 
detected  by  the  presence  of  a  small  tubercle  surrounding  it. 
This  orifice  is  found  in  the  small  triangular  depression  be- 
tween the  clitoris  and  vagina,  called  vestibulum,  and  is  the 
external  opening  of  the  urethra. 

The  female  urethra  is  about  an  inch  and  a  half  long,  pro- 
ceeds backward  and  upward  upon  the  upper  surface  of  the 
vagina,  with  which  it  is  very  strongly  connected,  passes 
beneath  the  symphysis  pubis,  to  which  it  is  also  attached 
by  the  anterior  ligaments  of  the  bladder,  and  after  forming 
a  slight  curve,  goes  to  terminate  in  the  neck.  This  canal 
is  larger  and  more  dilatable  than  the  male  urethra.  It 
consists  of  a  mucous  coat,  continuous  with  that  of  the  blad- 
der, of  a  red  color,  having  longitudinal  folds,  with  numer- 
ous mucous  follicles,  and  of  an  external  coat  of  condensed 
cellular  tissue,  which  is  also  elastic,  erectile,  and  muscular 
in  its  nature. 

The  orifice  of  the  vagina  is  directly  below  the  meatus  uri- 
narius, and  is  bounded  laterally  by  the  nymphse.  Its  form 


664  THE   VAGINA. 

is  oval,  and  presents  a  projecting,  and  somewhat  thickened 
and  corrugated  margin.  It  is  generally  closed  by  a  fold  of 
the  mucous  membrane,  called  hymen.  This  hymen  forms  a 
septum  which  presents  a  variety  of  forms ;  sometimes  it  is 
circular,  with  an  opening  in  the  centre  and  a  fringed  edge, 
sometimes  semilunar  witb  an  opening  in  front,  sometimes 
a  transverse  septum  with  two  openings,  then  again  a  com- 
plete septum  without  any  opening,  in  which  case  the  men- 
strual secretion  is  confined,  a  condition  whicb  is  attended 
with  some  danger ;  and  then  again  the  hymen  may  be 
entirely  wanting.  When  ruptured,  its  margin  presents 
from  two  to  six  or  more  fringe-like  processes  or  tubercles, 
termed  carunculce  myrti-formes . 

The  internal  organs  of  generation  include  the  vagina,  the 
uterus,  the  ovaries,  and  the  Fallopian  tubes. 

The  vagina  is  a  membranous  canal   leading  from   the 

FIG.  211. 


Yulvato  the  uterus,  and  is  situated  between  the  bladder  and 
rectum.  Its  direction  is  upward  and  backward.  It  is  about 
six  or  seven  inches  in  length,  and  in  the  axis  of  the  outlet 
of  the  lower  pelvis,  forming  an  angle  with  the  uterus,  and 
being  somewhat  concave  in  front  and  convex  behind.  Its 
anterior  and  posterior  surfaces  are  flattened  and  in  contact, 
the  anterior  being  the  shorter  of  the  two.  Its  anterior 
extremity  is  smaller,  and  presents  its  greatest  diameter 

Fie.  211  represents  the  female  internal  Organs  of  Generation,  a  Upper 
portion  of  vagina.  6  Os-uteri.  c  Cervix  uteri,  d  Body  of  the  uterus,  e  Fun- 
dus.  /Broad  ligament,  g  i  Fallopian  tube,  h  Round  ligament,  j  Fimbriated 
extremity  of  Fallopian  tube,  fc  Its  connection  with  the  ovary.  /  Ovary,  m 
Round  ligament. 


THE   VAGINA.  665 

vertically  ;  while  the  posterior  or  uterine  is  the  larger,  and 
has  its  greatest  diameter  transversely. 

The  vagina  surrounds  and  is  prolonged  for  a  short  dis- 
tance upon  the  uterus,  presenting  a  circular  depression. 
It  is  connected  in  front  to  the  bladder  very  closely,  by  means 
of  a  reddish  structure  resembling  the  dartos ;  and  has,  at 
this  point,  an  inseparable  attachment  to  the  urethra.  Be- 
hind, the  peritoneum  is  attached  to  its  upper  third,  while 
the  lower  is  connected  to  the  rectum  by  a  loose  dartoid  tis- 
sue ;  upon  its  sides  are  seen  the  levatores  ani,  the  pelvic 
fascia,  and  the  broad  folds  of  the  peritoneum. 

The  structure  of  the  vagina  consists  of  three  membranes, 
a  mucous,  erectile,  and  fibrous. 

The  mucous,  or  internal  coat,  is  continuous  with  that 
upon  the  labia,  and  presents  about  the  vulva  a  vermillion 
tinge,  while,  at  its  uterine  portion,  it  is  seen  of  a  marbled 
or  grayish  hue.  It  presents  numerous  transverse  rugae, 
which  are  not  unfolded,  but  form  a  roughened  surface  most 
distinct  on  the  upper  part.  Along  the  median  line  of  each 
surface  a  prominent  ridge  is  observed,  called  the  columns 
of  the  vagina. 

This  coat  abounds  with  mucous  follicles  and  papillae,  and 
is  covered  by  a  distinct  squamous  epithelium. 

The  erectile  or  middle  coat,  called  also  plexus  retiformis 
from  the  abundance  of  its  veins,  consists  of  a  spongy  tissue, 
and  is  compared  to  the  corpus  spongiosum  urethrse.  It  is 
enclosed  between  two  fibrous  laminae,  and  is  found  in  the 
greatest  quantity  about  the  anterior  extremity  of  the 
vagina.  The  sphincter  vagince  muscle  covers  this  middle 
coat. 

The  external  coat  is  fibrous,  consisting  of  condensed  cel- 
lular structure,  is  very  elastic,  and  resembles  the  dartos. 

On  each  side,  near  the  middle  of  the  orifice  of  the 
vagina,  and  beneath  the  sphincter  muscle,  is  seen  a  mucous 
gland  about  the  size  of  a  pea,  which  is  compared  to  Cow- 
per's  glands.  Their  excretory  ducts  open  in  front  of  the 
carunculae  myrtiformes. 

The  uterus  is  situated  between  the  bladder  and  the  rec- 


666  THE  UTERUS. 

turn,  in  the  cavity  of  the  pelvis.  Its  form  is  triangular  or 
pyriform.  Its  size  varies  ;  the  average  dimensions  being 
about  three  inches  in  length,  two  in  breadth  at  the  supe- 
rior portion,  and  one  inch  in  thickness,  in  the  uniinpregna- 
ted  state.  Its  divisions  are  into  ihefundus,  body,  and  neck. 

Thefundus  is  the  superior  portion  between  the  Fallopian 
tubes  ;  the  neck  is  the  inferior,  cylindrical,  and  constricted 
part ;  while  the  intermediate  portion  constitutes  the  body. 

The  direction  of  the  uterus  is  downward  and  backward, 
corresponding  to  the  axis  of  the  superior  strait,  and  forms 
an  angle  with  the  vagina  which  runs  forward  and  down- 
ward, in  the  axis  of  the  lower  strait. 

The  uterus  has  its  anterior  surface  flattened  and  covered 
in  its  upper  half  by  peritoneum,  which  is  reflected  upon 
the  bladder,  forming  the  anterior  or  vesico-uterine  liga- 
ment. The  posterior  surface  is  convex,  being  entirely 
covered  by  peritoneum,  which  is  reflected  upon  the  rectum, 
forming  the  posterior  or  recto-uterine  ligaments.  The  sides 
have  the  broad,  round,  ovarian  ligaments,  and  the  Fallo- 
pian tubes  attached  to  them. 

The  broad  ligaments  are  two  folds  of  the  peritoneum,  ex- 
tending from  the  uterus  to  the  sides  of  the  pelvis,  and  thus 
dividing  the  cavity  of  the  latter  by  a  transverse  septum, 
separating  the  bladder  from  the  rectum.  The  round  liga- 
ments are  situated  in  front  and  below  the  Fallopian  tubes, 
in  the  anterior  fold  of  the  broad  ligaments.  They  ascend 
to  the  internal  ring,  through  which  they  pass,  being  sur- 
rounded at  this  point  by  a  sheath  from  the  peritoneum, 
called  the  canal  of  Nuck  ;  thence  they  descend  the  inguinal 
canal,  and  pass  out  the  external  ring  to  be  lost  in  the  mons 
veneris.  These  ligaments  consist  of  condensed  cellular  or 
fibrous  tissue,  with  numerous  blood-vessels  and  nerves  from 
the  spermatic  plexus  ;  muscular  fibres  have  also  been  seen 
entering  into  their  composition.  Their  function  is  to  retain 
the  uterus  in  its  natural  position. 

The  ovarian  ligaments,  about  two  inches  in  length,  extend 
from  the  superior  and  lateral  angles  of  the  uterus,  below 
and  behind  the  Fallopian  tubes,  within  the  posterior  fold 


THE  UTERUS.  66? 

of  the  broad  ligaments,  to  the  ovaries.  They  are  regarded 
as  fibro-muscular,  and  serve  to  fix  the  ovaries.  The  supe- 
rior extremity  or  fundus  of  the  uterus  is  convex,  and  presents 
upward  and  forward  behind  the  bladder,  and,  in  the  undis- 
tended  state,  below  the  brim  of  the  pelvis.  The  inferior  ex- 
tremity or  cervix  looks  downward  and  backward,  and  is 
surrounded  by  the  vagina,  into  which  it  projects.  It  pre- 
sents the  os-tincce  or  uteri,  which  in  the  virgin  is  a  circu- 
lar opening,  with  smooth  borders,  but  in  the  female  who 
has  borne  children,  it  is  more  projecting,  larger,  slightly 
wrinkled,  and  more  transverse,  being  divided  into  an  an- 
terior and  posterior  lip.  The  anterior  or  superior  is  thicker 
than  the  posterior  or  inferior,  which  is  longer. 

The  uterus,  when  opened,  presents  a  triangular  cavity, 
the  base  of  the  triangle  being  above,  and  having  at  each 
angle  the  small  funnel-shaped  orifice  of  the  Fallopian  tube. 
The  sides  of  the  triangle  are  curvilinear,  and  the  inferior 
angle  forms  the  os-uteri,  which  is  seen  in  the  vagina.  This 
cavity  has  been  found  deficient.  The  cavity  of  the  neck  is 
cylindrical  and  flattened,  arid  smaller  at  either  end  than 
in  the  middle. 

Structure. — The  uterus  is  composed  of  an  external  or  se- 
rous coat,  an  internal  or  mucous,  and  an  intermediate  tis- 
sue, called  the  proper  fibrous  or  fibro-muscular,  with  blood- 
vessels and  nerves. 

The  serous  coat  and  its  ligaments  have  been  already 
described.  The  mucous  coat  is  a  thin,  smooth,  delicate 
membrane,  lining  the  internal  cavity,  of  a  pale  color,  be- 
coming brighter  during  menstruation,  and  covered  by  an 
epithelium,  columnar  and  ciliated.  In  the  neck  it  pre- 
sents, along  the  middle,  longitudinal  lines  or  columns, 
from  which  transverse  rugfe  or  folds  are  observed  to  pass, 
and  which,  from  their  arborescent  appearance,  receive  the 
name  of  arbor-vita;.  Between  these  folds  are  found  many 
mucous  follicles,  whose  mouths,  from  irritation  or  any 
other  cause,  becoming  obliterated,  present  the  form  of 
small  spherical  sacs,  from  the  accumulation  of  their  secre- 
tions, which  Naboth  mistook  for  eggs  or  rudiments  of  the 


668  THE  UTERUS. 

foetus,  and  were  called  ovula  Nabothi.  This  coat  is  more 
vascular  in  the  body  than  in  the  neck,  and  is  so  delicate  and 
difficult  of  demonstration  that  some  have  even  denied  its 
existence.  The  middle  coat  or  proper  tissue  is  composed  of 
strong,  grajish  fibres,  closely  interwoven,  and,  in  the  unini- 
pregnated  state,  presenting  the  density  of  cartilage  under 
the  knife.  The  true  character  of  these  fibres  is  yet  unset- 
tled, some  contending  that  they  are  muscular,  others  that 
they  are  fibrous,  while  others  regard  them  as  fibrous 
in  the  unimpregnated,  and  muscular  in  the  pregnant  or- 
gan. This  latter  opinion  seems  to  correspond  with  the 
changes  observed  in  the  uterus  before  and  after  pregnancy. 

In  the  former  or  quiescent  state,  the  uterus,  as  stated,  is 
condensed  and  compacted  in  its  fibres — hard,  without  con- 
tractility, and  presenting  very  little  the  appearance  of 
muscular  tissue ;  while  during  gestation  the  blood-vessels 
become  greatly  enlarged,  the  sensibility  much  exalted, 
and  the  fibres  softened,  loose,  immensely  contractile,  as 
proven  by  the  state  of  labor,  and  exhibiting,  in  an  eminent 
degree,  all  the  characteristics  of  muscles  of  organic  life. 

In  this  state  of  gestation  the  fibres  are  seen  to  be  ar- 
ranged into  two  layers,  a  superficial  and  deep — the  former 
longitudinal  upon  the  anterior  and  posterior  surface  of  the 
body,  oblique  upon  the  sides  and  fundus,  and  continued 
upon  the  Fallopian  tubes,  round,  and  ovarian  ligaments. 
The  deep  layer  is  seen  to  consist  of  two  series  of  conical 
fibres,  the  base  being  in  the  body  of  the  uterus,  and  the 
apex  at  the  Fallopian  tubes.  Around  the  neck  the  fibres 
are  circular,  intersecting  each  other  at  different  angles. 

Of  the  arteries  of  the  uterus,  two,  the  uterine,  come  from 
the  internal  iliac,  and  two,  the  spermatic,  from  the  aorta. 
The  uterine  veins  are  very  large,  and  during  pregnancy 
are  called  sinuses  ;  they  discharge  into  the  internal  iliac 
and  renal  veins,  and  the  vena  cava. 

The  nerves,  during  pregnancy,  are  also  large  and  well 
developed;  they  come  from  the  hypogastric  and  renal 
plexuses,  with  some  of  the  anterior  branches  of  the  sacral 
nerves.  The  lymphatics  of  the  uterus,  in  gestation,  are, 
like  the  veins,  very  large. 


THE   OVARIES.  669 

Function. — The  uterus  receives  and  retains  the  ovum 
during  the  whole  period  of  gestation,  from  a  short  time 
after  conception,  to  birth ;  and  is  also  the  prime  agent  in 
the  expulsion  of  the  child. 

THE   OVARIES. 

The  ovaries  (testes  muliebres,  Fig.  211,)  are  two  small, 
flattened,  oval  bodies,  one  on  each  side  of  the  pelvis, 
situated  in  the  posterior  fold  of  the  broad  ligament,  and 
connected  to  the  uterus  by  means  of  the  broad  and  round 
ligaments.  These  bodies  are  of  a  pale  color,  about  an 
inch  in  length,  and  about  an  inch  and  a  half  distant  from 
the  uterus.  Both  the  situation  and  size,  however,  depend- 
upon  age  and  pregnancy.  In  the  foetus,  like  the  testes, 
they  occupy  the  lumbar  regions,  whence  they  gradually 
descend  into  the  pelvis.  During  pregnancy  they  ascend 
into  the  abdomen  along  with  the  uterus,  and  after  partu- 
rition, for  a  short  time,  they  are  found  in  the  iliac  fossa. 
They  are  proportionally  larger  in  the  foetus  than  in  the. 
adult,  are  found  to  lessen  in  size  after  birth,  to  enlarge 
again  at  puberty,  and  then  to  diminish  and  become  wasted 
in  old  age. 

Structure. — Each  ovary  is  composed  of  an  outer  coat, 
which  is  serous  and  derived  from  the  peritoneum — a  middle, 
which  resembles  the  tunica  albuginea  of  the  testes,  and 
is  a  white,  strong,  fibrous  capsule,  sending  prolongations 
into  the  interior  of  the  gland,  which  divide  it  into  irregu- 
lar partitions,  like  the  interlacing  of  areolar  tissue.  Lining 
this  fibrous  coat  is  seen  a  vascular  one,  which  also  goes 
into  the  interior,  and  assists  in  forming  the  areolar  or  cel- 
lular tissue. 

This  latter  tissue  is  the  stroma  or  spongy  bed  of  authors, 
in  which  are  deposited  a  number  of  small  vesicles  called 
the  Graafan  vesicles.  Their  average  number  is  from  ten 
to  fifteen  in  the  mature  state,  though  the  microscope  re- 
veals numerous  others  not  yet  arrived  at  maturity.  Each 
of  the  Graafian  vesicles  is  represented  as  a  small,  trans- 
parent cyst,  varying  in  size  from  a  pin's  head  to  that  of  a 


670  THE  OVARIES. 

small  pea,  having  thin,  transparent  walls,  and  enclosing  a 
fluid,  either  colorless  or  yellow.  This  fluid  is  said  to  be 
albuminous,  and  to  contain  microscopic  granules,  and,  at 
the  least,  one  ovum.  The  walls  of  the  vesicle  are  observed 
to  consist  of  two  coats,  an  external  or  vascular,  regarded 
as  simply  the  thickening  of  the  surrounding  stroma,  and 
an  internal  coat,  transparent,  structureless,  and  lined  with 
an  epithelium,  constituting  the  true  ovisac. 

The  ovum,)  according  to  the  microscope,  is  about  the 
1-120  of  an  inch  in  diameter,  and  is  siirrounded  by  a 
transparent  membrane,  containing  the  yolk,  which  seems 
to  consist  of  granules  or  cells,  and  fat  globules.  In  the 
yolk  is  also  seen  the  germinal  vesicle  of  PurJcinje.  This 
vesicle  contains  a  transparent  fluid,  and  has  also  within  it 
the  germinal  spot  of  Wagner,  called  macula  germinativa, 
about  the  1-200  or  1-300  of  a  line  in  diameter.  The 
granules  of  the  ovum  are  arranged  into  a  membraniform 
structure  called  membrana  granulosa. 

The  corpus  luteum  is  a  yellowish  or  brownish  spongy 
tissue,  containing  a  small  cavity,  and  is  regarded  as  the 
remains  of  the  ruptured  Graafiari  vesicle  after  the  escape 
of  the  ovum  at  impregnation.  This  cavity  presents  a 
puckered  membrane  lining  it,  the  remains  of  the  ovisac. 
In  the  recent  state,  the  opening  into  this  sac  is  distinct, 
but  after  parturition  it  becomes  closed,  leaving  nothing  but 
a  cicatrix  to  indicate  its  position.  But  in  time  the  cicatrix 
is  known  to  be  effaced,  and  even  in  a  girl  of  only  five  years 
a  corpus  luteum  has  been  seen,  so  that  the  absence  of  the 
cicatrices  cannot  be  regarded  as  positive  proof  of  virginity, 
nor  the  presence  of  corpora  lutea  as  always  indicating  the 
state  of  impregnation. 

The  blood-vessels  of  the  ovaries  are  the  same  as  those 
iupplying  the  testes — the  spermatic. 

Function. — The  use  of  the  ovaries  seems  to  be  to  prepare 
the  germ  to  be  fecundated  by  the  male  semen.  They  are 
regarded  as  essential  in  the  function  of  reproduction,  since 
their  extirpation  is  always  followed  by  sterility. 


FALLOPIAN  TUBES.  671 

The  Fallopian  Tubes,  (Fig.  211.) — These  tubes,  named 
after  their  discoverer,  are  situated  within  the  fold  of  the 
broad  ligament,  along  its  superior  border.  They  are  two 
in  number,  one  on  each  side  of  the  pelvis,  and  extend 
from  the  superior  angles  of  the  uterus,  transversely  to 
the  distance  of  from  four  to  five  inches,  where  each  ter- 
minates in  a  free  and  fringe-like  extremity,  called  corpus 
fimbriatwn,  consisting  of  several  irregular  processes.  In 
this  course  the  tubes  have  the  round  ligaments  in  front, 
and  the  ovaria,  with  their  ligaments,  behind.  The  uter- 
ine extremity  has  a  very  small  orifice,  scarcely  admit- 
ting a  bristle,  while  the  outer  or  ovarian  end  presents  a 
trumpet-mouth  as  large  as  a  quill,  and,  with  its  processes, 
receives  the  name  of  morsus  didboli.  These  processes  or 
fimbrias  are  in  one  or  more  rows,  one  of  which  attaches 
them  to  the  ovary.  The  Fallopian  tubes  are  straight 
*at  the  inner  end,  but  pursue  a  tortuous  course  in  their 
outer  portion. 

Structure. — These  tubes  have  three  coats — an  outer,  loose, 
and  serous,  and  derived  from  the  broad  ligaments  ;  a  mid- 
dle, fibrous,  or  fibro-muscular  coat,  having  longitudinal 
fibres  externally,  and  circular  internally,  continuous  with 
those  of  the  uterus  ;  and  an  internal  or  mucous  coat,  which 
is  continuous  internally  with  that  of  the  uterus,  and  exter- 
nally with  the  peritoneum,  the  only  instance  of  direct 
continuity  between  a  mucous  and  serous  membrane.  This 
mucous  coat  is  thrown  into  longitudinal  folds,  admitting 
of  dilatation,  and  is  covered  by  an  epithelium,  both  ciliated 
and  columnar.  Neither  orifice  of  the  Fallopian  tube,  nor 
any  part  of  its  course  has  any  valve. 

Function. — The  use  of  these  tubes  is  to  transmit  the 
fecundating  principle  of  the  male  to  the  ovary,  and  to  con- 
duct to  the  uterus  the  ovum  when  fecundated.  Their  use 
is  the  same  as  the  oviduct,  and  it  is  found  that  the  ovum, 
in  its  passage  along  the  Fallopian  tube,  receives  a  double 
envelope — an  internal  layer,  of  an  albuminous  or  gelatinoui 
nature,  called  the  amnion,  and  an  external  fibrous  layer, 
called  the  chorion.  The  time  it  takes  the  ovum  to  traverse 


672  MUSCLES  OF  THE  PELVIS. 

one  of  these  tubes  is  estimated  at  from  eight  to  fourteen 
days.  The  uterus  has  been  preparing  a  membrane,  the 
decidua,  which  lines  its  internal  surface  by  the  time  the 
ovum  arrives.  That  which  covers  the  uterus  is  the  decidua 
vera;  that  which  covers  the  ovum,  the  decidua  reftexa. 
The  placenta  is  next  seen,  which  is  regarded  as  a  joint  pro- 
duction of  both  the  ovum  and  the  mother. 

SECTION  III. 

MUSCLES   OF   THE   PELVIS. 

Glutens  maximus. — Dissection. — Make  an  incision  round 
the  crest  of  the  ilium  to  the  coccyx,  extending  downward 
upon  the  outer  side  FIG.  212. 

of  the  thigh,  about 
three  or  four  inches  ; 
make  another  incision 
from  the  middle  of  the 
crest  of  the  ilium  to 
the  trochanter  ma- 

JOT.  Dissect  off  the  ^^•BPHMRiil  * 
integuments,  adipose 
structure,  and  fascia, 
in  the  direction  of 
the  last  incision, 
which  is  the  course 
of  the  fibres  of  the 
muscle,  and  which 
will  expose  its  whole  extent. 

It  arises  from  the  posterior  part  of  the  crest  of  the  ilium 
from  the  contiguous  dorsum  of  this  bone,  from  the  side  of 

FIG.  212  represents  the  Muscles  of  the  Pelvis  on  its  exterior,  a  Posterior 
•urface  of  the  sacrum.  6  Os-coccygis.  c  Crest  of  ilium,  d  Trochanter  ma- 
jor, e  Linea  aspera.  /  Gluteus  maximus.  g  h  Gluteus  medius.  i  Vastui 
externus.  j  Greater  sacro-sciatic  ligament,  k  Tuberosity  of  the  ischium.  i 
Pyriformis.  m  Gemellus  superior,  o  Gemellus  inferior.  «  Obturator  inter- 
nus.  p  Obturator  externus.  q  Quadratus  femoris.  r  Insertion  of  gluleuf 
maximus.  s  Biceps  femoris.  t  Semi-tendinosus.  u  Semi-membranosus.  9 
Gracilis. 


MUSCLES   OF   THE  PELVIS.  673 

the  sacrum  and  coccyx,  and  from  the  great  sacro-sciatic 
ligament,  by  fleshy  and  aponeurotic  fibres.  Its  fibres  are 
collected  into  distinct  fasciculi,  presenting  a  thick,  strong, 
and  large  quadrangular  fleshy  mass  of  muscle,  of  a  rough 
and  coarse  appearance,  descending  obliquely  downward 
and  forward  to  terminate  in  a  broad,  thick  tendon,  which 
is  inserted  into  the  upper  third  of  the  linea  aspera,  also  into 
a  rough  ridge,  leading  from  this  line  to  the  trochanter,  and 
into  the  fascia  lata  over  the  vastus  externus.  The  fasci- 
culi of  this  muscle  are  separated  by  processes  of  the  fascia 
fernoris,  and  it  almost  entirely  covers  all  the  muscles  on 
the  back  of  the  pelvis  together  with  the  origin  of  the  ham- 
string muscles.  A  large  bursa  is  observed  between  the 
tendon  and  vastus  externus,  and  a  third  where  this  muscle 
glides  over  the  tuberosity  of  the  ischium. 

Function. — To  extend  the  thigh  and  rotate  it  outward ; 
also  to  support  the  trunk  in  the  erect  position. 

Turn  down  the  gluteus  maximus  upon  the  thigh,  and 
we  expose  the  gluteus  medius,  gluteus  minimus,  pyriformis, 
gemelli,  obturator,  and  quadratus  femoris. 

The  gluteus  medius  (Fig.  212)  is  a  triangular,  flat  mus- 
cle, having  its  anterior  portion  uncovered  by  the  gluteus 
maximus.  It  arises  from  the  outer  edge  of  the  whole  of 
crest  of  the  ilium,  except  its  posterior  part,  by  fleshy  and 
aponeurotic  fibres ;  also  from  the  dorsum  of  the  ilium,  be- 
tween its  crest  and  semicircular  ridge,  and  from  the  strong 
fascia  which  covers  it.  It  is  inserted  by  a  broad,  thick  ten- 
don, into  the  upper  and  outer  part  of  the  trochanter  major, 
and  into  a  portion  of  the  shaft  of  the  bone. 

Function. — To  extend  the  thigh  and  turn  it  outward.  A 
bursa  is  seen  between  the  tendon  of  this  muscle  and  the 
tendinous  insertion  of  the  rotators. 

The  gluten  minimus,  (Fig.  212,)  so  named  from  being 
the  smallest  of  the  three  glutei,  is  seen  by  raising  the  last. 
It  arises  from  the  dorsum  of  the  ilium,  between  the  semi- 
circular ridge  and  the  margin  of  the  acetabulum,  and  ending 
in  a  round,  strong  tendon,  is  inserted  into  the  upper,  ante- 
rior portion  of  the  trochanter  major,  having  a  bursa  between 
43 


674  MUSCLES  OF  THE  PELVIS. 

it  and  the  insertion  of  the  glutens  medius.  Function. — The 
same  as  the  last,  and  also  to  strengthen  the  ilio-femoral 
articulation. 

The  pyriformis  (Fig.  212)  is  a  triangular  muscle,  which 
arises  by  its  base  within  the  pelvis,  fleshy  and  tendinous, 
from  the  second,  third,  and  fourth  divisions  of  the  sacrum, 
and  forms  a  thick,  conical  belly,  which  passes  out  at  the  upper 
part  of  the  great  sciatic  notch,  receiving  fibres  in  its  course, 
from  the  sciatic  ligament  and  posterior  inferior  part  of 
the  ilium.  It  is  inserted  by  a  round  tendon  into  the  su- 
perior portion  of  the  fossa  at  the  root  of  the  trochanter 
major.  Function. — To  rotate  the  thigh  outward. 

The  gemelli  (Fig.  212)  are  two  small  muscles.  The  supe- 
rior arises  from  the  spine  of  the  ischium,  the  inferior  from 
the  tuber  of  the  ischium  and  the  great  sciatic  ligament- 
They  run  parallel  to  each  other,  and  both  are  inserted  into 
the  root  of  the  trochanter  major. 

Function. — To  rotate  the  thigh  outward,  and  strengthen 
the  capsular  ligament. 

The  obturator  internus  (Fig.  212)  arises  from  the  pelvic 
surface  of  the  obturator  ligament,  except  at  the  superior 
part  where  the  obturator  vessels  and  nerve  pass  out ;  also 
from  the  obturator  margin  and  plane  of  the  ischium.  Its 
fibres  converge  to  a  flat  tendon,  which  passes  through  the 
lesser  sciatic  foramen,  and  thence  goes  between  the  gemelli 
muscles  to  be  inserted  into  the  fossa  at  the  root  of  the 
great  trochanter.  As  this  muscle  passes  over  the  ischium, 
there  is  found  interposed  a  bursa,  and  another  between  the 
tendon  and  the  gemelli. 

Function. — To  rotate  the  thigh  outward. 

Obturator  Externus. — Dissection. — Most  of  the  muscles  on 
the  anterior  and  internal  thigh  at  the  superior  part  must 
be  removed,  when  this  muscle  will  be  seen  to  arise  fleshy 
from  the  anterior  surface  of  the  obturator  ligament,  except 
where  the  obturator  vessels  pass  out,  and  also  from  the 
surrounding  margin  of  the  thyroid  foramen.  The  fibres 
converging,  end  in  a  tendon  which  passes  outward  and 
ackward  in  a  groove  behind  the  neck  of  the  femur,  to  be 


FASCIA  OF   THE   PELVIS.  675 

inserted  into  the  lower  part  of  the  fossa,  at  the  root  of  the 
great  trochanter. 

Function. — To  rotate  the  thigh  outward. 

The  Quadratics  Femoris  (Fig.  212)  is  situated  lower 
down  than  the  other  rotators,  and  arises  from  the  external 
surface  of  the  tuber  ischii  fleshy  and  tendinous. 

Its  fibres  run  transversely,  and  are  inserted  fleshy  and 
tendinous  into  the  back  part  of  the  great  trochanter  and 
intertrochanteric  line.  A  bursa  is  found  between  this 
muscle  and  the  little  trochanter. 

Function. — To  rotate  the  thigh  outward. 

The  psoas  muscles  and  iliacus  internus  are  noticed  in 
another  place. 

SECTION    IV. 
FASCIA   OF  THE  PELVIS. 

The  pelvic  fascia  is  regarded  as  a  continuation  of  the 
iliac,  which  descends  into  the  pelvis  from  the  brim,  to 
which  it  is  attached,  to  about  midway  its  depth,  where 
it  divides  into  two  laminae,  the  superior  pelvic  aponeurosis 
or  vesical  fascia,  and  the  lateral  pelvic  aponeurosis  or  obtu- 
rator fascia. 

The  superior  or  vesical  fascia  is  seen  by  removing  the 
peritoneum,  when  it  will  be  found  to  line  the  inner  surface 
of  the  levator  ani  muscle,  and  to  assist  in  closing  the  pelvis, 
fixing  its  several  viscera,  and  resisting  pressure  from  the 
abdominal  muscles.  It  is  reflected  from  the  inferior  edge 
of  the  symphysis  pubis  upon  the  neck  of  the  bladder  and 
prostate  gland,  constituting  the  anterior  true  ligaments  of 
the  bladder.  Upon  this  organ  it  is  reflected  laterally, 
forming  its  lateral  ligaments.  Posteriorly  it  becomes  thin 
and  cellular,  and  is  lost  upon  the  sacrum.  Mr.  Tyrrell 
notices  a  reflection  of  this  fascia  between  the  bladder  and 
rectum,  which  he  terms  recto-vesical.  Another  process,  the 
rectal  fascia^  descends,  and  covers  the  lower  part  of  the 
rectum  behind  and  laterally.  This  latter  fascia,  with  the 
recto-vesical  in  front,  forms  a  complete  aponeurotic  invest- 
ment for  the  lower  portion  of  the  rectum. 


676  PERINEUM   OF  THE  MALE. 

The  obturator  fascia  covers  the  obturator  interims  muscle, 
and  is  upon  the  outside  of  the  levator  ani.  This  fascia  is 
connected  with  the  great  sciatic  ligament,  and  the  rami  of 
the  pubis  and  ischium,  and  is  continuous  with  the  triangu- 
lar ligament.  It  forms  a  sheath  for  the  pudic  vessels  and 
nerves,  and  sends  off  a  process  which  covers  the  lower  or 
perineal  surface  of  the  levator  ani,  called  the  ischio  rectal 
or  anal  fascia. 

Triangular  Ligament,  or  Ligament  of  Camper,  or  Deep 
Perineal  Fascia. — This  ligament  consists  of  a  strong  apon- 
eurosis,  forming  a  septum  between  the  pelvis  and  perineum. 
It  is  situated  below  the  symphysis  pubis,  attached  to  and 
filling  up  the  space  between  the  rami  of  the  pubis  and 
ischium.  Its  shape  is  triangular,  the  base  being  below 
and  the  apex  above.  It  consists  of  two  larninge,  one  ante- 
rior, upon  which  the  bulb  rests,  the  other  posterior,  sur- 
rounding the  membranous  part  of  the  urethra,  and  enclos- 
ing the  prostate  gland. 

This  ligament  is  penetrated  by  the  urethra  about  an 
inch  below  the  pubic  arch.  Between  its  two  laminee,  at 
the  inferior  margin,  and  posterior  to  the  bulb  of  the  ure- 
thra, are  seen  Cowper's  glands,  already  described.  At  the 
upper  part  of  this  ligament,  between  its  layers,  and  imme- 
diately below  the  symphysis,  about  half  an  inch  broad, 
thick  and  strong,  and  stretching  from  side  to  side  of  the 
rami  of  the  pubis,  is  another  called  the  sub  or  inter-pubic 
ligament.  These  ligaments  help  to  form  the  anterior 
boundary  of  the  pelvis,  besides  giving  passage  to  the  ure- 
thra, and  supporting  and  fixing  its  bulb. 

SECTION  V. 
THE   PERINEUM   OF   THE   MALE. 

The  different  elements  composing  the  perineum  consist 
of  fascia,  muscles,  blood-vessels,  and  nerves. 

Dissection. — The  subject  is  placed  as  in  the  operation  for 
lithotomy,  that  is,  upon  the  back,  with  the  thighs  and 
knees  bent  upon  the  trunk,  and  the  feet  and  hands  bound 
together.  The  knees  being  thrown  apart,  and  the  scrotum 


PERINEUM  OF   THE  MALE. 


secured  upward  by  means  of  the  double  tenaculum,  an  in- 
cision is  made  transversely  along  the  base  of  the  scrotum  ; 

FIG.  213. 

1716 


"7/7 


then  two  vertical  incisions  running  from  the  extremities 
of  the  first,  along  the  rami  of  the  pubis  and  ischium,  to  a 
point  corresponding  to  the  apex  of  the  coccyx.  These  two 
latter  incisions,  being  united  at  their  coccygeal  end,  will 
thus  complete  and  describe  the  perineal  space.  This  space 
has  along  its  median  line  a  prominent  ridge  termed  the 
raphe  of  the  perineum,  which  is  found  to  extend  along  the 
scrotum  and  penis  as  far  as  the  prepuce.  The  integument 
should  first  be  dissected  off. 

The  fascice  of  the  perineum  consist  of  the  superficial, 
middle,  and  deep.  The  superficial  is  seen  immediately  on 
removing  the  integuments,  and  consists  of  condensed  cel- 
lular tissue,  continuous  with  that  upon  the  inner  side  of 
the  thigh,  attached  to  the  rami  of  the  pubis  and  ischium, 
and  about  the  anus  containing  a  quantity  of  soft,  granular, 
adipose  matter.  This  fascia  gives  a  covering  to  the  mus- 
cles of  the  perineum  ;  or  more  properly  speaking,  on  being 
removed,  is  found  to  cover  another  fascia,  which  has  been 
called  the  middle,  and  consists  of  a  semi-transparent  and 

FIG.  213  represents  the  Muscles  of  the  Male  Perineum.  1  Accelerator 
urinae.  2  Erector  penis.  3  Transversus  perinei.  4  Sphincter  ani.  5  Leva- 
tor  ani.  6  Coccygeus.  7  Gluteus  maximus.  8  Adductor  tertius  or  magnus. 
9  Adductor  brevis.  10  Adductor  primus  or  longus.  17  17  Corpora  cavernosa. 
16  Urethra.  14  Spermatic  cord. 


678  MUSCLES  OF  THE  PERINEUM. 

fine  but  dense  aponeurosis,  forming  the  immediate  cov- 
ering to  the  muscles.  This,  however,  is  sometimes  called 
the  deep  fascia,  though  this  latter  term,  to  avoid  confusion, 
has  been  restricted  to  another  fascia  still  deeper,  the  tri- 
angular ligament ,  which  has  been  already  described. 

The  muscles  of  the  perineum  are  seen  on  removing  the 
fascia,  and  are  ten  in  number,  the — 

Sphincter  externus,  Transversus  perinei, 

Sphincter  internus,  Coccygeus, 

Erectores  penis,  Levatores-ani. 
Acceleratores  urinae, 

The  sphincter  externus,  or  ani,  (Fig.  213,)  is  a  cutane- 
ous muscle,  surrounding  the  anus,  and  presenting  a  flat, 
thin,  pale,  and  elliptical  plane  of  fibres.  It  has  two  fixed 
points  of  attachment — one  to  the  os-coccygis  and  recto-coc- 
cygeal  ligament  behind,  which  is  called  its  origin ;  the 
other  to  the  central  point  of  union  of  the  perineal  muscles 
in  front,  and  also  to  the  superficial  fascia  and  raphe,  which 
is  the  insertion.  On  surrounding  the  anus,  it  expands 
outward  nearly  to  the  tuberosities  of  the  ischia. 

Function. — To  .-close  the  anus,  and  draw  the  bulb  of  the 
urethra  back,  or  the  coccyx  forward. 

Sphincter  internus,  or  orbicularis. — This  muscle  surrounds 
the  lower  portion  of  the  rectum,  is  in  close  contact  with 
the  mucous  membrane,  and  is  regarded  simply  as  a  contin- 
uation and  thickening  of  the  circular  muscular  coat  of  this 
intestine.  Function. — To  assist  in  closing  the  anus. 

The  erector  or  compressor  penis  (Fig.  213)  arises,  fleshy 
and  tendinous,  from  the  inner  and  anterior  surface  of  the 
tuber  ischii.  Its  fibres  adhere  to  the  rami  of  the  ischium 
and  pubis,  and  end  in  a  tendinous  expansion  which  is  lost 
or  inserted  into  the  fibrous  membrane  of  the  corpus  caver- 
nosum  or  crura  penis.  This  muscle  is  long  and  narrow. 

Function. — To  draw  down  and  compress  the  penis,  and 
thus  aid  in  its  erection  by  preventing  the  return  of  the 
blood,  though  its  use,  by  some,  is  not  considered  as  fully 
understood. 


MUSCLES  OF  THE  PERINEUM. 

The  accelerator  urince,  or  ejaculator  seminis,  (Fig.  213,)  is 
situated  upon  the  back  part  of  the  corpus  spongiosum 
urethras  and  its  bulb.  It  arises,  along  with  its  fellow,  from 
the  central  line  or  raphe,  forming  a  thin  muscle  upon  the 
middle  of  the  perineum,  the  fibres  of  which  diverge  Jike 
the  feathers  of  a  quill,  the  posterior  covering  the  bulb, 
being  inserted  into  the  triangular  ligament,  and  sometimes 
attached  to  the  rami  of  the  ischium  and  pubis.  The  mid- 
dle fibres  are  short  and  surround  the  urethra ;  while  the 
anterior  are  the  longest  and  ascend  upon  the  crura  of  the 
penis.  Function. — To  expel  the  semen  and  the  last  drops 
of  urine. 

The  transversalis  perinei  (Fig.  213)  arises  from  the 
tuberosity  of  the  ischium  at  its  inner  side ;  the  fibres  run 
transversely  and  are  inserted  into  the  central  point  of  the 
perineum,  behind  the  acceleratores.  This  muscle  is  fre- 
quently indistinct  and  sometimes  absent.  Function. — To 
fix  the  bulb  and  dilate  it. 

A  fasciculus  of  fibres,  called  transversus  perinei  alter,  is 
sometimes  seen  in  front  of  the  transversalis,  and  is  regarded 
as  a  portion  of  the  accelerator  urinaa,  being  inserted  into  the 
common  central  point  and  side  of  the  bulb.  Its  function  is 
the  same  as  that  of  the  transversalis. 

The  coccygeus  (Fig.  213)  is  a  small,  triangular  muscle, 
seen  within  the  pelvis.  It  arises  tendinous  and  fleshy  from 
the  spine  of  the  ischium,  and  is  inserted  into  the  side  of  the 
coccyx  and  extremity  of  the  sacrum. 

Function.— To  bring  the  coccyx  forward,  and  to  assist  in 
closing  the  lower  and  posterior  part  of  the  pelvis. 

The  levator  ani  (Fig.  213)  is  a  broad,  thin  muscle,  form- 
ing a  great  part  of  the  floor  of  the  pelvis.  It  arises  fleshy 
from  the  back  part  of  the  symphysis  pubis,  from  the  supe- 
rior margin  of  the  thyroid  foramen ;  from  the  obturator 
fascia  as  it  stretches  in  the  form  of  a  semilunar  chord  from 
the  upper  margin  of  the  thyroid  foramen  towards  the 
spine  of  the  ischium ;  fleshy  and  tendinous  from  the  spine 
and  inner  surface  of  the  ischium.  The  fibres  of  this  muscle 
converge  and  descend  backward.  Its  anterior  fibres,  which 


680  MUSCLES  OP  THE  PERINEUM. 

descend  along  the  side  of  the  lower  fundus  of  the  bladder, 
the  membranous  part  of  the  urethra,  and  the  prostate 
gland,  are  inserted  into  the  central  point  of  the  perineum. 
The  middle  fibres  are  inserted,  according  to  Dr.  Horner, 
into  the  semicircumference  of  the  rectum,  between  the  lon- 
gitudinal fibres  of  the  latter  and  the  circular  fibres  of  the 
sphincter  ani,  while  the  posterior  fibres  are  inserted  into 
the  os-coccygis  and  back  part  of  the  rectum. 

Function. — To  draw  the  rectum  forward  and  assist  in  ex- 
pelling the  fasces,  urine,  and  semen. 

The  compress  ores  or  levatores  urethra,  described  by  Mr. 
Wilson,  and  the  transverse  compressors  of  Mr.  Guthrie,  are 
regarded  as  nothing  more  than  the  anterior  portions  of  the 
levator  ani. 

In  the  female  perineum,  the  erector  ditoridis  muscle  cor- 
responds with  the  erector  penis,  and  the  sphincter  vaginae, 
with  the  accelerator  urince. 

Blood-vessels  of  the  perineum. — The  arteries  come  from 
the  internal  pudic,  and  consist  of,  1.  Inferior  hcemorrlioidal, 
going  to  the  side  of  rectum  and  anus.  2.  Superficial  peri- 
neal.  3.  Transverse  perineal.  These  two  latter  supply  the 
perineal  space  and  go  to  the  scrotum.  4.  Artery  of  the  bulb, 
which  passes  between  the  layers  of  the  triangular  ligament 
and  goes  to  the  bulb  and  corpus  spongiosum.  The  veins 
corresponding  to  the  arteries  terminate  in  the  internal 
iliac  vein. 

Nerves  of  the  Perineum.^-These  come  from  the  pudic 
nerve,  which  arises  from  the  lower  part  of  the  sacral  plexus 
and  takes  the  course  of  the  internal  pudic  artery.  The  in- 
ferior branch  of  the  pudic  is  the  proper  perineal  nerve,  and 
gives  off  the  external  perineal,  superficial  perineal,  and  nerve 
of  the  bulb. 


SUMMARY   OP  MUSCLES   OF  THE  TRUNK. 


681 


SUMMARY  OF  MUSCLES,  BLOOD-VESSELS,  AND  NERVES  OF  THE  TRUNK. 

Under  the  arrangement  which  we  have  adopted  the  mus- 
cles of  the  neck  form  a  part  of  those  belonging  to  the  trunk. 
The  order  will  be,  1.  The  neck,  2.  The  back,  3.  Abdomen, 
4.  Chest,  5.  Pelvis. 

MUSCLES    OF    THE    NECK. 

To  the  neck  proper  are  assigned  18  pais  of  muscles,  ar- 
ranged, agreeably  to  Mr.  Harrison,  into  four  groups,  besides 
which  there  are  five  other  groups,  including  twenty-one 
pairs  and  two  single  muscles;  making  in  all  thirty-nine 
pairs  and  two  single  muscles. 

FIRST  GROUP— Two  pairs  of  Muscles. 


Platysma-myoides. 
Sterno-cleido  mastoideus. 

SECOND  GROUP — Four  pairs. 
Sterno-hyoideus. 
Sterno-thyroideus. 
Thyro-hyoideus. 
Omo-hyoideus. 

THIRD  G ROUP— Five  pairs. 
Digastricus. 
Mylo-hyoideus. 
Genio-hyoideus. 
Hyo-glossus. 
Genio-hyo-glossus. 

FOURTH  GROUP — Seven  pairs. 
Longus  colli. 

Rectus  capitis  anticus  major. 
Ilectus  capitis  anticus  minor. 
Rectus  capitis  lateralis. 
Scalenus  anticus. 
Scalenus  medius. 
Scalenus  posticus. 

FIFTH  GROUP — Three  pairs. 
Stylo-hyoideus. 
Stylo-glossus. 
Stylo-pharyngeus. 

SIXTH  GROUP-— four  pairs. 
Lingualis. 
Superficial  lingual. 


Transverse  lingual. 
Vertical  lingual. 

These  are  the  muscles  proper  of  the 
tongue'. 

SEVENTH  GROUP — Three  pairs. 
Constrictor  pharyingis  inferior. 
Constrictor  pharingis  medius. 
Constrictor  pharyngis  superior. 
Muscles  proper  to  the  pharynx. 

EIGHTH  GROUP — Four  pairs  and  a  single 

muscle. 

Levator  palati. 

Circumflexus,  or  tensor  palati. 
Constrictor  isthmi-faucium,  or  palato- 

glossus. 

Falato-pharyngeus. 
Azygos-uvul®,  a  single  muscle. 
Muscles  proper  of  the  Dalate. 

NINTH  GROUP — Set-en  pairs  and  a  single 

muscle. 

Crico-thyroideus. 
Crico-arytenoideus  posticus. 
Crico-arytenoideus  lateralis. 
Thyro-arytenoideus. 
Arytenoideus  obliquus. 
Arytenoideus  transversus,  a  single  mus- 
cle. 

Aryteno-epiglottideus. 
Thyro-epiglottideus. 

Muscles  proper  of  the  larynx. 


682 


SUMMARY  OF  MUSCLES   OF   THE  TRUNK. 


MUSCLES    OP    THE    BACK,    ARRANGED    INTO    SIX    LAYERS. 


FIRST  LAYER — Two  pairs  of  Muscles. 

Trapezius. 

Latissimus  dorsi. 

SECOND  LAYER — Three  pairs- 
Levator  anguli  scapula. 
Rhomboideus  minor. 
Rhomboideus  major. 

THIRD  LAYER — Four  pairs. 
Serratus  posticus  superior. 
Serratus  posticus  inferior. 
Splenius  capitis. 
Splenius  colli. 

FOURTH  LAYER — Seven  pairs. 
Sacro-lumbalis. 
Longissimus  dorsi. 
Spinalis  dorsi. 
Cervicalis  ascendens. 


Transversalis  colli. 

Trachelo-mastoideus. 

Complexus. 

FIFTH  LAYER — Seven  pairs. 
Rectus  capitis  posticus  major. 
Rectus  capitis  posticus  minor. 
Rectus  capitis  lateralis. 
Obliquus  capitis  superior. 
Obliquus  capitis  inferior. 
Semi-spinalis  dorsi. 
Semi-spinalis  colli. 

SIXTH  LAYER — Five  pairs. 
Multifidus  spinae. 
Levatores  costarum. 
Supra-spinales. 
Inter-spinales. 
Inter-transversales. 


MUSCLES    OP    THE    ABDOMEN SEVEN    PAIRS. 


Obliquus  externus  abdominis    descen- 

dens. 

Obliquus  internus  abdominis  ascendens. 
Transversalis. 


Cremaster. 
Rectus  abdominis. 
Pyramidalis. 
Quadratus  lumborum. 


MUSCLES    OF    THE    CHEST — FOUR   PAIRS,    PROPERLY    SPEAKING. 


Pectoralis  major. 
Pectoralis  minor. 
Subclavius. 

Serratus  major  anticus. 
Intercostales  externi. 


Intercostales  interni. 
Levatores  costarum. 
Triangularis  sterni. 
Diaphragm. 


MUSCLES    OF    THE    PELVIS. 


THOSE    OF    THE   INTERIOR   ARE, 

Psoas  magnus. 
Psoas  parvus. 
Iliacus  internus. 

THOSE    OF    THE   EXTERIOR   ARE, 

Gluteus  maximus. 
Gluteus  medius. 
Gluteus  minimus. 
Pyriformis. 
Gemellus  superior. 
Gemellus  inferior. 
Quadratus  femoris. 


Obturator  externus. 
Obturator  internus. 

THOSE    OF    THE   INFERIOR    PELVIS    ARE, 

Sphincter  ani. 
Transversus  perinei. 
Accelerator  urina3. 
Erector  penis. 
Levator  ani. 
Coccygeus. 
Compressor  urethrae. 
Erector  clitoridis. 
Constrictor  vaginae. 


BLOOD  VESSELS  AND  NERVES  OF  THE  TRUNK. 


683 


BLOOD-VESSELS   OF  THE  TRUNK. 


For  a  brief  summary  of  the  blood-vessels  of  the  trunk, 
we  refer  to  the  following  figure,  214,  and  its  explanation  ; 
and  for  further  detail  to  figures  8,  9,  and  120. 


FIG.  214. 


a  Aorta,  its  commence- 
ment, b  Thoracic  aorta. 
c  Abdominal  aorta,  d  Ar- 
teria  innominata.  e  Com- 
mon carotid,  f  Superior 
thyroid  artery,  g  Right 
subclavian.  h  Vertebral. 
1  i  Inferior  thyroid,  j  An- 
terior cervical,  k  Trans- 
verse cervical.  I  Superior 
scapular,  m  Superior  in- 
tercostal, n  Internal  mam- 
mary, o  Left  carotid,  p 
Left  subclavian.  q  Medi- 
astinal.  r  Upper  intercos- 
tal arteries,  s  (Esophageal. 
t  Phrenic,  u  Lower  in- 
tercostal artery,  v  Ccel- 
iac,  its  division  into  the 
gastric,  hepatic,  and  sple- 
nic arteries,  to  Superior 
mesenteric.  x  Emulgent. 
y  Inferior  mesenteric.  z 
Aorta,  its  division  into  the 
primitive  iliacs.  a  a  Mid- 
dle sacral,  b  b  Common 
iliacs.  c  c  External  iliacs.  d  d  Epigastric,  e  e  Circumflexa  ilii.  // 
Internal  iliac,  g  g  Ilio-lumbar.  h  h  Lateral  sacral,  ii  Gluteal.  jj 
Vesical.  k  k  Obturator.  I  I  Ischiatic.  m  m  Internal  pudic. 


NERVES  OF  THE  TRUNK. 


See  figures  14,  152,  155,  203,  204,  and  153,  with  their 
explanations. 


684  RELATIONS   OP  THE  MOUTH. 


SECTION    VI. 

ANATOMICAL  AND  PHYSIOLOGICAL  RELATIONS   OF   THE  MOUTH  WITH 
THE   DIFFERENT   ORGANS   OF   THE   TRUNK. 

The  several  organs  of  the  trunk  comprise  the  digestive, 
pulmonary,  urinary,  and  generative. 

The  mouth  has  a  relation  more  or  less  intimate,  both  by 
structure  and  function,  with  all  these  various  organs. 
With  the  digestive  and  pulmonary  the  relation  is  direct 
and  inseparable.  The  same  mucous  membrane,  for  in- 
stance, which  lines  the  mouth,  is  traced  down  the  oesopha- 
gus  into  the  stomach,  and  through  the  whole  alimentary 
canal.  It  is  continued  also  into  the  various  excretory 
ducts  of  the  salivary  glands,  liver,  pancreas,  and  mucous 
follicles,  all  of  which  organs  pour  their  several  fluids  into 
the  mouth  and  digestive  tube.  This  same  mucous  mem- 
brane is  traced  from  the  mouth,  in  another  direction,  into 
the  larynx,  trachea,  bronchi,  and  lungs.  The  mucous 
membrane  is  also  found  in  the  kidneys,  ureters,  and  blad- 
der, the  genital  organs  of  the  male  and  female,  receiving 
here  the  name  of  the  genito-urinary  mucous  membrane, 
which,  however,  is  not  directly  traceable  to  the  mouth. 

The  cellular  tissue  forms  another  element  of  anatomical 
continuity  between  the  mouth  and  the  various  organs. 

The  par-vagum,  one  of  the  divisions  of  the  eighth  pair  of 
nerves,  forms  a  great  chain  of  nervous  connection  between 
the  posterior  mouth,  and  the  oesophagus,  stomach,  larynx, 
lungs,  and  brain.  The  fifth  pair  of  nerves,  which  are  mostly 
nerves  of  sensibility,  bountifully  supply  all  the  organs  of 
the  mouth,  and  connect  directly  with  the  brain,  spinal 
marrow,  and  the  several  organs  of  sense.  The  portio  dura 
of  the  seventh  pair,  also  forms  an  element  of  nervous  com- 
munication between  the  mouth  and  other  parts.  The  blood- 
vessels, supplying  the  mouth,  come  from  the  same  great 
arterial  tube  which  supplies  all  the  organs  of  the  body. 

The  physiological  relation  of  the  mouth  with  the  various 
organs  is  as  close  as  the  anatomical. 


RELATIONS  OF  THE  MOUTH.  C85 

The  digestive  function,  for  instance,  comprises  a  series 
of  sub-divisions  or  functions,  constituting  so  many  links  or 
stages,  each  one  of  which  is  essentially  related  with,  and 
dependent  upon  every  other  and  the  whole;  and  the  whole 
upon  each,  for  the  completion  and  perfection  of  this  won- 
derful and  complicated  process,  styled  digestion. 

The  function  of  digestion  begins  in  the  mouth  by  sub- 
jecting the  crude  material  of  nutrition  to  the  several  opera- 
tions of  mastication,  insalivation,  and  deglutition,  and  the 
aliment  having  arrived  in  the  stomach,  the  function  is 
there  continued,  by  converting  this  aliment  into  chyme, 
whence  it  is  conducted  into  the  small  intestine,  and  there 
undergoes  its  final  change,  by  being  formed  into  chyle,  and 
thus  completing  the  whole  process  of  digestion. 

But  the  relation  of  the  mouth,  in  this  series  of  physio- 
logical actions,  does  not  stop  here ;  for  we  follow  the  chyle 
through  the  great  trunk  of  the  absorbent  system,  into  the 
left  subclavian  vein,  thence  through  the  heart  to  the  lungs, 
where,  with  the  venous  blood,  and  by  atmospherical  agency, 
it  undergoes  its  final  and  most  perfect  change  ;  in  other 
words,  is  formed  into  arterial  Wood,  the  only  and  proper 
pabulum  by  which  the  mouth,  as  well  as  the  whole  body 
with  all  its  organs,  is  built  up  and  sustained. 

To  accomplish  this  result,  we  now  trace  this  fluid  blood 
from  the  lungs  into  the  heart  and  arteries,  by  which  latter 
it  is  distributed  over  the  whole  body,  and  consequently 
brought  back  to  supply  the  mouth,  the  point  where  began 
the  first  change  in  this  most  beautiful  series  of  operations 
so  essential  to  the  formation  of  this  vital  fluid. 

These  several  relations,  anatomical  and  physiological, 
thus  briefly  sketched,  which  the  mouth  has  with  the  vari- 
ous organs,  shows  an  intimacy  of  connection,  not  only  close, 
but  inseparable.  Hence  the  dental  student  will  perceive 
the  absolute  necessity  of  not  confining  his  anatomical 
studies  solely  to  the  mouth,  but  of  examining  studiously 
every  organ  and  portion  of  the  body  with  which  the  mouth 
has  any  relation,  as  necessary  steps  to  becoming  completely 
master  of  his  profession. 


PART  FOUKTH. 


THE  LANGUAGE  OF  ANATOMY. 

III.  THE  EXTREMITIES. 


PART  FOUKTH. 


SUPERIOR    EXTREMITY. 

THE   SUPERIOR  EXTREMITY  COMPRISES  BONES,  LIGAMENTS,  MUSCLES, 

FASCIJE,  BLOOD-VESSELS,  AND  NERVES,  AND  WILL  BE  EXAMINED 

UNDER  THESE   SEVERAL  HEADS  RESPECTIVELY. 


CHAPTER  I. 

THE    BONES. 

THE  Bones  are  arranged  into  those  of  the  .Shoulder, 
Arm,  Forearm,  and  Hand. 

SECTION    I. 
BONES  OF  THE  SHOULDER. 

The  bones  of  the  shoulder  are  two  in  number :  1.  The 
Scapula ;  2.  The  Clavicle. 

THE  SCAPULA  OR  SHOULDER  BLADE,    (Fig.   215.) 

The  Scapula  is  situated  upon  the  posterior  and  superior 
part  of  the  chest.  Its  form  is  triangular,  and  it  presents 
two  surfaces,  three  edges,  and  three  angles.  The  anterior 
surface  looks  toward  the  ribs,  and  is  also  the  internal  sur- 
face or  subscapular  fossa.  It  is  concave,  divided  by  several 
irregular  lines,  and  occupied  by  the  subscapular  muscle. 
The  posterior  or  external  surface  is  the  dorsum,  and  is  cut 
transversely  into  two  unequal  parts  by  a  very  prominent 
process  called  the  spine  of  the  scapula. 

This  spine  proceeds  forward,  and  terminates  in  the  aero- 
mlon  process,  which  is  flattened  superiorly  and  inferiorly, 
and  overhangs  the  shoulder  joint.  This  spine  also  divides 
the  dorsum  into  the  sityra  and  infra  spinal  fossce^  which 
contain  the  supra  and  infra  spinal  muscles.  The  upper 
edge  of  the  spine  has  the  trapezius  attached  to  it,  the 
lower  edge  the  deltoid  muscle. 
44 


690 


THE  SCAPULA. 


The  superior  edge  or  costa  is  situated  between  the  ante- 
rior and  superior  angles,  is  thin  and  short;  and  has  at  its 
fore-part  a  notch,  which  is  formed  into  a  foramen  by  a 
ligament,  and  transmits  the  supra-scapular  nerve.     The 
F[G.  215.  oino-hyoid,     supra-spinatus,     and 

sub-scapular  muscles  are  also  at- 
tached to  this  edge. 

At  its  anterior  portion  the  cora- 
coid  process  arises.  This  is  long 
and  narrow,  runs  upward  and 
forward,  and  bounds  the  glenoid 
cavity  internally.  Its  superior 
surface  is  rough  for  the  attach- 
ment of  ligaments,  the  inferior  is 
smooth  for  the  sub-scapular  mus- 
cle. The  extremity  of  this  process 
frequently  presents  three  distinct 
surfaces,  the  inner  of  which  has 
the  pectoralis  minor  inserted  into 
it;  the  middle  gives  origin  to  the  coraco-brachialis,  and 
the  outer  to  the  short  head  of  the  biceps. 

The  anterior  or  axillary  edge  looks  downward  and  back- 
ward, and  extends  from  the  anterior  to  the  inferior  angle. 
It  is  the  thickest  of  the  three  edges,  and  gives  attachment 
to  the  teres  major,  teres  minor,  and  long  head  of  the 
triceps.  The  posterior  or  vertebral  edge,  called  also  the 
base,  extends  from  the  superior  to  the  inferior  angle,  and 
is  the  longest  of  the  three  margins.  Below  the  spine  are 
attached  to  it  the  rhomboideus  major,  opposite  the  origin 
of  the  spine  the  rhomboideus  minor,  above  the  spine  the 
levator  scapulae,  and  along  its  whole  extent  the  inser- 
tion of  the  serratus  major  anticus.  At  the  junction  of  the 
superior  costa  and  the  base  is  the  superior  angle.  At  the 

FIG.  215  represents  the  Scapula,  a  Supra-spinal  fossa,  b  Infra-spinal 
fossa,  c  Superior  edge  or  costa.  d  Coracoid  notch,  e  Anterior  or  inferior 
edge.  /  Glenoid  cavity,  g  Inferior  angle,  h  Neck,  i  Posterior  edge  or 
base,  j  Spine  of  scapula,  fc  Point  of  attachment  of  rhomboideus  minor.  I 
Acromion  process,  m  Nutritious  foramen,  n  Coracoid  process,  o  Point 
where  the  deltoid  is  attached. 


THE   CLAVICLE.  691 

union  of  the  superior  and  anterior  costa  is  the  anterior 
angle,  which  contains  the  glenoid  cavity.  This  cavity  is 
ovoidal,  deepened  hy  the  glenoid  ligament,  and  is  hroader 
below  than  above.  It  is  covered  with  cartilage,  and  has 
the  long  head  of  the  biceps  arising  from  its  superior  mar- 
gin. It  articulates  with  the  head  of  the  humerus.  Behind 
this  cavity  the  bone  contracts,  and  is  called  the  neck  or 
cervix.  The  inferior  angle  is  formed  by  the  junction  of  the 
base  and  anterior  costa ;  it  presents  a  flat  surface  for  the 
origin  of  the  teres  major. 

Structure. — The  scapula  is  composed  of  two  compact 
layers  with  cellular  substance  between  them.  The  latter  is 
most  abundant  in  the  processes,  while  in  the  centre  of  the 
dorsum  the  bone  is  diaphanous.  Its  development  takes 
place  from  several  points,  one  for  each  of  the  processes,  one 
for  the  centre  of  the  body,  one  for  the  base,  and  one  for 
the  inferior  angle. 

An  ossific  centre  is  noticed  in  the  infra  spinal  fossa 
about  the  seventh  or  eighth  week,  during  the  first  year  in 
the  coracoid  process,  at  puberty  in  the  acromion  process, 
in  the  fifteenth  year  at  the  inferior  angle,  during  the 
seventeenth  or  eighteenth  year  at  the  base,  and  about  the 
twentieth  or  twenty-fifth  year  the  bone  is  found  complete. 

THE  CLAVICLE  OR  COLLAR  BONE. 

The  clavicle  is  situated  transversely,  between  the  upper 
extremity  of  the  ster-  FIG.  216. 

num  and  the  acro- 
mion process  of  the 
scapula.  Its  shape 
is  that  of  the  italic  s. 

It  is  longer  in  the  female  than  the  male,  and  consists  of 
a  body  and  two  extremities.  The  body  is  rather  cylindri- 
cal at  the  sternal,  and  flattened  at  the  acromial  end.  Its 

FIG.  216  represents  the  Clavicle,  a  Anterior  surface,  b  Point  of  attach- 
ment of  sterno-cleido  mastoid  muscle,  c  Sternal  end  of  Clavicle,  d  Acro- 
mial end.  e  Articular  surface.  /  Where  the  conoid  ligament  is  attached. 
g  Where  the  rhomboid  ligament  is  attached. 


692  HUMERUS. 

upper  surface  is  smooth.  Its  lower  presents  a  ridge  for 
the  attachment  of  the  rhomboid  or  costo-clavicular  liga- 
ment,, and  a  groove  for  the  subclavian  muscle.  The  sternal 
portion  is  convex  in  front,  and  concave  behind.  The  hu- 
meral end  is  just  the  reverse.  Two-thirds  of  the  anterior 
margin  give  origin  to  the  pectoralis  major,  the  rest  to  the 
deltoid  muscle.  The  posterior  margin  has  one  or  more 
foramina  for  nutritious  vessels.  The  sternal  superior  sur- 
face gives  origin  to  the  sterno-cleido-mastoideus.  The 
sternal  extremity  is  triangular,  thick,  and  forms  the  ar- 
ticulating surface.  Its  margin  has  ligaments  attached  to 
it.  The  acromiol  end  is  flat,  presents  an  articular  surface, 
and  covers  the  coracoid  process. 

Its  Structure  is  compact  and  cellular.  The  former  is  very 
condensed  and  strong  in  the  centre  of  the  bone  ;  the  latter 
abounds  mostly  at  the  extremities. 

Function. — To  support  the  scapula  and  prevent  its  fall- 
ing forward  or  inward,  and  also  to  protect  the  vessels  and 
nerves  as  they  pass  to  the  extremity.  Its  development  is 
from  two  points  of  ossification,  (one  for  the  body  and  the 
other  for  the  sternal  end)  and  is  found  to  be  very  perfect  in 
the  foetus.  Ossification  begins  in  the  clavicle  sooner  than 
in  any  other  bone,  as  early  even  as  the  fifth  week  of  intra- 
uterine  life.  The  sternal  epiphysis  is  ossified  during  the 
fifteenth  and  twentieth  years.  It  is  articulated  to  the  ster- 
num and  scapula. 

SECTION    II. 

THE   HUMERUS   OR   ARM-BONE. 

The  humerus  is  the  largest  bone  in  the  upper  extremity, 
and  is  situated  between  the  scapula  above,  and  the  radius 
and  ulna  below.  It  consists  of  a  body  and  two  extremities. 

The  body  or  shaft  is  cylindrical ;  its  upper  anterior  fourth 
is  divided  by  the  bicipital  groove  which  lodges  the  long  head 
of  the  biceps  muscle.  The  anterior  edge  of  this  groove  has 
the  pectoralis  major  inserted  into  it ;  its  posterior  edge 
receives  the  insertions  of  the  latissimus  dorsi  and  teres  major 
muscles.  About  the  centre  of  this  bone  is  seen  a  rough  tri- 


IIUMERUS. 


693 


*•* 


angular  surface  for  tlie  insertion  of  the  deltoid  muscle,  and 
about  the  same  point  an  oblique  vascular  foramen.  The  pos- 
terior surface  is  smooth,  and  covered  by  the  triceps  muscle. 

The  upper  or  scapular  extremity  presents  a  smooth,  hemi- 
spherical surface,  covered  with  cartilage,  and  called  the 
head.  It  articulates  with  the  glenoid  cavity  FIG.  217. 
of  the  scapula.  Just  below  and  around  the 
head  there  is  a  furrow  or  contraction  of  the 
bone  called  its  neck.  It  is  rough  and  gives 
attachment  to  the  capsular  ligament.  Below 
the  neck  the  humerus  swells  into  two  pro- 
cesses called  tuberosities.  They  are  two  in 
number,  external  and  internal,  or  the  greater 
and  lesser.  The  external  presents  three  de- 
pressions ;  the  anterior p,  middle,  and  posterior^ 
To  the  anterior  the  supra  spinatus,  to  the 
middle  the  infra  spinatus,  and  to  the  posterior 
the  teres  minor  muscles  are  attached.  The  in- 
ternal tuberosity  gives  insertion  to  the  tendon 
of  the  subscapularis. 

The  inferior  extremity  of  the  humerus  is, 
flattened,  and  is  bounded  externally  and  inter- 
nally by  two  ridges  for  the  attachment  of  •* 
muscles  and  the  intermuscular  ligaments.  These  ridges 
lead  to  the  two  projections  called  condyles.  The  internal 
condyle  is  most  prominent  and  has  attached  to  it  the  inter- 
nal lateral  ligament,  and  the  pronator  and  flexor  muscles. 
The  external  condyle,  less  prominent,  gives  attachment 
to  the  external  lateral  ligament  and  to  the  supinator  and 
extensor  muscles.  Between  these  two  condyles  a  smooth 
articulating  surface  is  observed,  separated  by  a  ridge.  The 

FIG.  217  represents  the  anterior  surface  of  the  Humerus.  a  Shaft  or  body 
of  the  Humerus.  6  Head,  c  Anatomical  neck,  d  Greater  tuberosity.  e  Lesser 
tuberosity.  /  Bicipttal  groove,  g-  Point  of  insertion  for  the  pectoralis  major. 
h  Internal  bicipital  ridge,  i  Point  where  the  deltoid  is  inserted,  j  Nutritious 
foramen,  k  Articular  surface  for  the  radius.  I  Articular  surface  for  the  ulna, 
m  External  condyle.  n  Internal  condyle.  o  p  Condyloid  ridges,  q  Lesser 
sigmoid  cavity. 


694 


RADIUS. 


inner  portion,  called  the  trochlea,  is  the  larger,  and  articu- 
lates with  the  ulna.  The  outer  receives  the  head  of  the 
radius.  Ahove  the  trochlea,  and  in  front  of  the  humerus, 
is  the  anterior  or  lesser  cavity  for  receiving  the  coronoid 
process  of  the  ulna.  Behind  the  humerus,  and  above  the 
trochlea,  is  the  posterior  or  greater  cavity  for  receiving  the 
olecranon  process  of  the  ulna.  Between  these  two  cavities 
the  hone  is  transparent,  and  sometimes  wanting. 

Structure. — The  humerus  consists  of  compact  structure 
in  its  body,  and  is  cellular  at  its  extremities.  It  contains 
a  large  medullary  canal.  It  is  articulated  to  the  scapula, 
radius  and  ulna.  Its  development  is  from  eight  points,  viz  : 
one  for  the  body,  one  for  the  head,  one  for  each  tuberosity, 
one  for  the  trochlea,  one  for  each  condyle,  and  one  for  the 
small  head.  Ossification  is  noticed  to  begin  shortly  after 
that  of  the  clavicle.  At  birth  the  extremities  are  found 
cartilaginous,,  while  the  bony  shaft  is  nearly  complete. 
From  the  close  of  the  first  and  during  the  second  and  third 
years,  ossific  centres  are  observed  in  the  head  and  tuberosi- 
ties — during  the  third  and  sixth  years  the  trochlea  and 
small  head  of  the  humerus — during  the  fifth  to  the  seven- 
teenth year  ossification  appears  in  the  condyles,  and  the 
bone  is  found  complete  about  the  twentieth  year. 

SECTION    III. 
BONES   OF   THE   FOREARM — THE  RADIUS,  (Fig.  218.) 

The  radius  is  situated  upon  the  outer  side  of  the  ulna, 
the  palm  of  the  hand  looking  upward,  and  is  the  shorter 
bone  of  the  two  occupying  the  forearm. 

It  consists  of  a  body  and  two  extremities.  The  body  or 
shaft  of  the  radius  presents  three  surfaces,  and  is  rather 
triangular  in  shape.  The  anterior  surface  is  covered  below 
by  the  pronator  quadratus,  and  is  there  broad ;  a  little 
Above  its  centre  is  seen  the  orifice  of  an  oblique  vascular 
•canal.  The  posterior  surface  is  convex  above  and  gives 
attachment  to  the  supinator  brevis,  and  is  concave  in  the 
middle  for  the  extensors  of  the  thumb.  The  external 
surface  is  round,  and  in  its  centre  is  rough  for  the  insertion 
of  the  pronator  teres. 


RADIUS. 


695 


The  upper  extremity,  styled  the  head,  presents  two 
smooth  articulating  surfaces;  the  one,  a  superficial  cavity, 
and  superior,  articulates  with  the  small  head  FIG.  218. 
of  the  huinerus;  the  other  forms  the  circum- 
ference and  articulates  with  the  lesser  sig- 
moid cavity  of  the  ulna.  Below  the  head  the 
bone  contracts,  and  is  called  the  cervix  or 
neck.  Below  the  neck,  or  where  the  latter 
and  the  body  unite,  is  the  tubercle  which 
gives  insertion  to  the  tendon  of  the  biceps. 
It  is  also  covered  by  a  bursa.  The  lower  or 
carpal  extremity  is  the  larger  of  the  two, 
and  is  widest  transversely.  It  is  bounded 
externally  by  the  styloid  process,  which  gives 
attachment  to  the  external  lateral  ligament 
of  the  wrist.  Internally  is  a  smooth  concave 
surface  for  articulating  with  the  lower  end 
of  the  ulna.  The  carpal  surface  is  smooth 
and  divided  by  a  ridge  into  two  unequal  articulating 
portions ;  the  outer  and  larger  is  for  the  scaphoid  bone, 
the  inner  receives  the  lunar.  The  margin  of  the  carpal 
surface  presents  a  prominent  ridge  to  which  the  capsular 
ligament  is  attached.  On  the  posterior  surface  of  this  car- 
pal extremity  several  grooves  are  noticed.  At  the  side  and 
base  of  the  styloid  process  is  a  groove  for  the  tendons  of  the 
extensor  ossis  metacarpi,  and  minor  pollicis  muscles.  Next 
to  this  is  a  larger  groove  for  the  tendons  of  the  exten- 
sor carpi  radialis  longior  and  brevior.  On  the  middle,  and 
next  in  order,  is  a  groove  for  the  extensor  major  pollicis, 
and  on  the  ulnar  side  of  this  is  another  and  larger  for  the 
extensor  communis  and  indicator.  Structure. — Cellular  in 
the  extremities  and  compact  in  the  centre. 

FIG.  218  represents  the  Radius'and  Ulna,  a  Shaft  of  the  ulna.  6  The  greater 
sigmoid  cavity,  c  Lesser  sigmoid  cavity.  dOlecranon  process-  « Coronoii 
process.  /Nutritious  foramen,  g  Sharp  edge  for  attachment  of  interosseous 
membrane,  h  Lower  extremity  of  ulna,  t  Styloid  process,  j  Shaft  of  radius, 
fc Its  head.  /Neck,  m Its  tuberosity.  n Oblique  line,  o Lower  extremity  of 
radius,  pits  styloid  process. 


696  ULNA. 

Its  development  is  from  three  points,  one  for  the  body  and 
one  for  each  extremity.  Ossification  begins  in  the  radius 
during  the  sixth  week,  shortly  after  that  of  the  humerus. 
At  birth  both  extremities  are  cartilaginous.  In  the  lower 
end  an  ossific  point  is  seen  about  the  close  of  the  second 
year,  and  in  the  upper  end  from  the  fifth  to  the  seventh, 
the  bone  being  completed  about  the  twentieth  year.  It 
is  articulated  to  the  humerus,  ulna,  scaphoid  and  lunar 
bones. 

THE  ULNA,  (Fig.  218.) 

The  ulna  is  situated  at  the  inner  side  of  the  radius,  the 
palm  of  the  hand  being  uppermost.  It  is  triangular  in 
shape,  and  consists  also  in  a  body  and  two  extremities.  The 
body  presents  three  ridges  and  three  surfaces.  The  external 
or  radial  ridge  is  most  prominent,  runs  the  greater  part  of 
the  length  of  the  bone  and  gives  attachment  to  the  inter- 
osseous  ligament ;  the  anterior  ridge  is  round,  and  has  the 
flexor  profundus  and  pronator  quadratus  attached  to  it; 
the  posterior  ridge  is  distinct  above  and  gives  attachment 
to  the  anconeus.  Between  these  ridges  are  so  many  sur- 
faces all  covered  by  muscles.  The  anterior  surface  has  a 
foramen  a  little  above  its  centre,  looking  obliquely  upward, 
and  conducts  the  nutritious  vessel.  The  superior  extremity 
is  much  larger  than  the  lower  and  forms  the  greater  por- 
tion of  the  elbow-joint.  It  presents  two  processes ;  the  one 
anterior  and  smaller,  called  coronoid;  the  other  posterior 
and  much  larger,  termed  olecranon.  The  coronoid  process 
is  triangular  and  sharp,  and  is  received  into  the  anterior 
cavity  of  the  lower  end  of  the  humerus.  Its  anterior  sur- 
face gives  insertion  to  the  brachialis  anticus  muscle.  Its 
outer  surface  is  hollowed  into  the  lesser  sigmoid  cavity, 
which  articulates  with  the  side  of  the  head  of  the  radius. 

The  olecranon  process  has  its  posterior  surface  covered 
by  a  bursa,  and  is  rough  for  the  insertion  of  the  tendon  of 
the  triceps,  and  its  extremity  presents  a  point  which  is 
received  into  the  posterior  or  greater  cavity  of  the  humerus. 
Between  these  two  processes  is  a  large  concave  surface, 


CARPUS.  69  T 

smooth,  and  covered  with  cartilage,  called  the  greater  sig- 
moid  cavity,  which  receives  the  trochlea  of  the  humerus. 
This  cavity  is  divided  by  a  vertical  ridge,  and  about  its 
centre  by  a  transverse  ridge,  which  terminates  internally 
in  a  notch,  in  which  fatty  matter  is  found. 

The  inferior  or  carpal  extremity  is  small,  and  presents  a 
projecting  process,  called  the  styloid,  to  which  the  internal 
lateral  ligament  of  the  wrist  is  attached.  External  to 
this  process  is  a  round  smooth  head  for  articulating  with 
the  small  cavity  on  the  inner  side  of  the  radius;  and 
between  these  two  processes,  on  the  back  of  the  ulna,  is  a 
groove  for  the  passage  of  the  tendon  of  the  extensor  carpi 
ulnaris. 

Structure. — Same  as  the  radius.  Like  that  bone,  it  is 
developed  from  three  points  of  ossification.  Ossification 
begins  in  the  ulna  during  the  sixth  week,  shortly  after  it 
takes  place  in  the  radius  and  humerus.  At  birth  both 
extremities  are  cartilaginous.  The  lower  end  has  in  its 
centre  an  ossific  point  about  the  fourth  or  fifth  year.  The 
olecranon  is  ossified  from  the  seventh  to  the  tenth,  and 
the  bone  is  completed  about  the  twentieth  year.  It  is 
articulated  to  the  humerus  and  radius. 

SECTION   IV. 
THE   HAND. 

The  Hand  is  composed  of  the  carpus,  metacarpus,  and 
phalanges. 

THE   CARPUS   OR   WRIST,  (Fig.  219.) 

The  carpus  consists  of  two  rows  of  bones,  eight  in 
number.  The  first  row  contains  the  os  scaphoides,  lunare, 
cuneiforme,  and  pisiforme,  which  are  adjacent  to  the  bones 
of  the  forearm.  The  second  row  is  next  to  the  metacarpus, 
and  contains  the  trapezium,  trapezoides,  magnum  and 
unciforme. 

The  05  scai^lioides,  (os  naviculare,)  so  called  from  its  fan- 
cied resemblance  to  a  boat,  is  situated  upon  the  radial  side, 
and  is  the  largest  bone  in  the  upper  row.  Its  upper  sur- 


698 


CARPUS. 


face  is  convex  and  articulates  with  the  radius.     Its  lower 
surface  is  concavo-convex  and  articulates  with  the  trape- 
zium and  trapezoid.     Its  ulnar  or  inner  surface  articulates 
FIG.  219.  with   the   os-lunare   and   os  mag- 

num, while  its  external  or  radial 
face  gives  attachment  to  the  ex- 
ternal lateral  ligament. 

The  os-lunare,  so  called  from 
its  semi-lunar  shape,  is  convex 
ahove  to  receive  the  radius,  and 
concave  helow  to  articulate  with 
the  magnum  and  unciforme.  Its 
ulnar  surface  joins  the  cuneiform, 
its  radial  the  scaphoid. 

The  os-cuneiforme,  so  named 
from  its  wedge-like  shape,  is  on 
the  ulnar  side  of  the  lunar,  and  articulates  with  it.  The 
lower  surface  is  concave,  and  articulates  with  the  unci- 
forme, and  its  anterior  surface  is  flat  and  smooth  where  it 
joins  the  pisiforme. 

The  os  pisiforme,  so  called  from  its  resemblance  in  size 
and  form  to  a  pea,  is  the  smallest  bone  in  the  wrist,  and  is 
situated  upon  the  palmar  surface  of  the  last,  with  which  it 
is  articulated.  It  gives  insertion  to  the  flexor  carpi  ulnaris 
above,  and  origin  to  the  abductor  minimi  digiti  below. 

The  trapezium  is  the  first  bone  on  the  radial  side  of  the 
second  row;  it  is  concave  above  to  receive  the  scaphoid, 
and  below  it  joins  the  metacarpal  bone  of  the  thumb. 
Internally  it  articulates  with  the  trapezoides  and  second 
metacarpal  bone ;  on  its  anterior  surface  is  observed  a 
groove  for  the  tendon  of  the  flexor  carpi  radialis. 

The  trapezoides  is  smaller  than  the  last,  with  which  it 
articulates,  and  of  very  irregular  shape.  Above  it  is  con- 

FIG.  219  represents  the  Carpus,  a  Ulna,  b  Radius,  clnter-articular-fibro 
cartilage,  d  Metacarpal  bone  of  the  thumb,  e  Metacarpal  bone  of  the  first 
finger.  /Metacarpal  bone  of  the  second  finger,  g  Metacarpal  bone  of  the 
third  finger,  h  Melacarpal  bone  of  the  fourth  finger.  S  Scaphoides.  L  Lu- 
nare.  C  Cuneiforme.  P  Pisiforme.  T  T  Trapezium  and  trapezoides.  M 
Os  magnum.  U  Unciforme.j  ^ 


METACARPUS.  699 

cave  to  join  the  scaphoid ;  below  it  unites  with  the  second 
metacarpal  bone,  and  internally  with  the  os  magnum. 

The  os  magnum,  so  named  from  fts  size,  is  situated  upon 
the  ulnar  side  of  the  last,  and  is  the  largest  of  the  bones  of 
the  carpus.  Its  superior  surface  articulates  with  the  sca- 
phoid and  lunar  bones ;  its  inferior,  with  the  second,  third, 
and  fourth  metacarpal.  Internally  it  meets  the  unciform, 
externally  the  trapezoides.  The  dorsal  surface  is  broad, 
the  palmar  narrow. 

The  os  unciforme,  so  named  from  its  hook-like  process,  is 
the  next  in  size  to  the  os  magnum.  Its  superior  surface 
joins  the  os-lunare,  its  external  the  magnum,  its  internal 
the  cuneiform,  and  its  base  the  fourth  and  fifth  metacarpal. 
Its  dorsal  surface  is  rough ;  and  its  palmar  presents  the 
hook-like  process  for  the  attachment  of  "'the  annular  liga- 
ment. 

Structure. — The  bones  of  the  carpus  consist  of  cellular 
structure,  covered  by  a  delicate  lamina  of  compact  bone. 
They  are  developed  from  a  single  point  of  ossification, 
except  thounciform,  which  has  two. 

Ossification  is  observed  to  begin  in  the  os  magnum  and 
unciforme,  at  the  close  of  the  first  year ;  in  the  cuneiform, 
at  the  close  of  the  third;  in  the  trapezium  and  semilunare, 
in  the  fifth ;  in  the  scaphoid^  from  the  sixth  to  the  eighth; 
in  the  trapezoides,  from  the  eighth  to  the  ninth,  and  in  the 
pisiforme  in  the  twelfth  year. 

THE  METACARPUS,  (Fig.  220.) 

The  metacarpus  is  situated  between  the  carpus  and 
the  phalanges,  and  consists  of  five  bones.  Those  corre- 
sponding to  the  fingers  are  parallel  to  each  other ;  the 
one  for  the  thumb'  stands  out  from  the  rest  at  an  angle. 
Each  metacarpus  is  composed  of  a  head,  shaft  and  base. 
The  head  is  at  the  digital  extremity,  and  articulates  with 
the  first  phalanx  of  the  fingers ;  the  shaft  is  triangular, 
and  marked  laterally  for  the  attachment  of  the  interossei 
muscles ;  the  base  is  superior,  and  articulates  with  its  fel- 
lows and  with  the  carpal  bones. 


"700 


METACARPUS. 


All  the  bones  of  the  raetacarpal  series  have  a  convexity 
on  their  dorsal  surface  and  a  concavity  on  their  palmar. 

FJG.  220.  The  metacarpal  bone  of  the  thumh 

is  the  strongest  and  shortest  of  the 
whole;  its  slightly  concave  carpal 
end  articulates  with  the  trapezium  ; 
its  slightly  concave  phalangeal  end 
with  the  first  hone  of  the  thumh. 
On  either  side  of  the  phalangeal 
extremity  a  tubercle  is  seen  on 
which  is  placed  a  sesamoid  bone. 

The  second  metacarpal  bone,  or 
that  of  the  forefinger,  is  distin- 
guished from  the  rest  by  its  greater 
length ;  it  articulates  at  its  carpal 
end  by  a  deep  concavity  in  the 
middle  with  the  trapezoides.  There 
is  a  smooth  articular  face  for  the  trapezium  on  the  one  side 
and  the  magnum  on  the  other.  The  base,,  on  its  palmar 
surface,  presents  a  rough  portion  for  the  insertion  of  the 
flexor  carpi  radialis,  and  a  like  roughness  on  the  dorsal 
base  for  the  insertion  of  the  extensor  carpi  radialis  lon- 
gior.  The  palmar  portion  of  the  shaft  is  divided  by  a 
longitudinal  ridge  into  two  surfaces  for  the  interosseous 
muscles. 

The  third  metacarpal  bone  is  the  next  in  size,  but  rather 
shorter  than  the  last.  Its  carpal  extremity  is  triangular, 
and  articulates  with  the  os  magnum ;  it  has  on  its  radial 
side  a  tubercle  for  the  insertion  of  the  extensor  carpi 
radialis  brevior.  On  either  side  of  the  base  are  seen  articu- 
lar faces  for  the  second  and  fourth  metacarpal  bones. 

The  fourth  metacarpal  bone  is  smaller  and  shorter  than 
the  third.  Its  carpal  extremity  articulates  with  the  unci- 

FIG.  220  represents  the  Metacarpus  and  Phalanges,  a  Scaphoides.  b  Lunare. 
c  Cuneiforme.  cJPisiforme.  e  Trapezium.  /Groove  for  tendon  of  flexor  carpi 
radialis  g  Trapezoides.  /iOs-magnum.  i  Unciforme.  jj  Metacarpal  bones. 
k  k  Phalanges— first  row.  1 1  Phalanges— second  row.  m  m  Phalanges— third 
row.  n  First  phalanx  of  the  thumb,  o  Last  phalanx  of  the  thumb. 


PHALANGES.  7  01 

forme  and  the  magnum,  and  by  its  lateral  portions  with 
the  third  and  fifth  metacarpal  bones. 

The  fifth  metacarpal  bone  is  smaller  and  shorter  than  the 
fourth.  Its  carpal  extremity  presents  a  double  articulating 
surface,  the  larger  for  the  unciforme,  the  smaller  for  the 
fourth  metacarpal  bone.  The  base  presents  a  tubercle  for 
the  insertion  of  the  extensor  carpi  ulnaris. 

Development. — Ossification  of  the  metacarpal  bones  com- 
mences by  two  centres — one  for  the  digital  extremity,  and 
one  for  the  shaft.  About  the  tenth  or  twelfth  week  the 
metacarpal  bone  of  the  thumb  presents  an  exception  to  this 
rule,  by  having  its  ossific  centre  in  the  carpal  extremity. 
The  epiphyses  show  themselves  about  the  second  or  third 
year ;  and  about  the  twentieth  the  metacarpal  row  is  com- 
pleted. 

THE  PHALANGES,    (Fig.    220.) 

The  phalanges  compose  the  bones  of  the  thumb  and  fin- 
gers, and  have  each  a  shaft  and  two  extremities. 

The  thumb  has  two  bones;  each  of  the  fingers  three,  placed 
in  rows.  The  first  row  or  phalanx  is  next  to  the  metacar- 
pal bones.  The  bones  of  this  row  have  their  base  concave 
for  receiving  the  head  of  the  corresponding  metacarpal 
bone,  and,  on  either  side,  a  small  tubercle  for  the  lateral 
ligament.  The  lower  extremity  presents  two  small  heads, 
or  a  pulley-like  formation,  for  articulating  with  the  second 
phalanx ;  the  sides  form  ridges  for  the  thecal  attachments. 
The  dorsal  surface  is  convex  and  smooth,  the  palmar 
concave. 

The  second  phalanx  is  smaller  than  the  first;  its  superior 
extremity  presents  two  small  cavities  for  the  two  heads  of 
the  first  phalanx ;  the  lower  extremity  is  slightly  concave 
for  articulation  with  the  third  phalanx. 

The  third  or  last  phalanx  is  the  smallest  of  the  three, 
and  is  remarkable  for  having  its  lower  extremity  flat,  thin, 
and  semicircular,  and  its  palmar  surface  rough.  The  first 
phalanx  of  the  thumb  is  stronger  and  shorter  than  those 
of  the  fingers,  while  its  second  or  last  phalanx  is  broader. 


T02  LIGAMENTS  OF  THE  SHOULDER. 

Development. — The  phalanges  are  developed  from  two 
centres — one  for  the  base  and  one  for  the  shaft.  Ossifica- 
tion begins  about  the  same  time  as  in  the  metacarpal  bones, 
and  is  observed  first  in  the  third  phalanx,  then  in  the  first, 
and  last  of  all  in  the  second  phalanx.  During  the  third 
and  fourth  years  the  epiphyses  of  the  first  row  are  seen ; 
during  the  fourth  and  fifth  those  of  the  second  row ;  and 
during  the  sixth  and  seventh  year  those  of  the  last  row. 
All  the  phalanges  are  completed  by  the  twentieth  year. 

SECTION    V. 
LIGAMENTS   OF   THE   SUPERIOR   EXTREMITY. 

The  ligaments  to  be  considered  are  those  of  the  shoulder, 
arm,  forearm,  and  hand. 

LIGAMENTS  OF  THE  SHOULDER. 

The  bones  of  the  shoulder  being  composed  of  the  clavicle 
and  scapula,  we  have  clavicular  and  scapular  ligaments ; 
and  the  clavicle  being  connected  with  the  sternum,  ribs, 
and  scapulae,  we  have  hence  a  division  of  the  ligaments 
into  sterno-clavicular,  costo-clavicular,  and  scapulo-cla- 
vicular. 

Sterno-clavicular  articulation,  (Fig.  141.) — This  articula- 
tion has  a  capsular  ligament,  an  inter-articular  cartilage, 
an  inter-clavicular  ligament,  and  two  synovial  membranes. 

The  capsular  ligament  is  a  strong,  fibrous,  membrane 
surrounding  the  joint,  and  covered  by  the  origin  of  the 
sterno-cleido-mastoideus  at  its  anterior  portion.  This  cap- 
sule has  its  fibres  thickened  in  front  and  behind — -hence 
the  names  of  the  anterior  and  posterior  sterno-clavicular 
ligaments. 

The  anterior,  called  also  the  radiated  ligament,  proceeds 
from  the  anterior  extremity  of  the  clavicle  downward 
and  inward  to  the  articular  margin  of  the  cavity  of  the 
sternum.  The  posterior  is  not  so  distinct,  but  pursues  a 
course  behind  the  joint  similar  to  the  anterior. 

The  inter-articular  cartilage  is  seen  on  opening  the  joint. 
It  is  circular  in  shape,  and  completely  separates  the  ster- 


LIGAMENTS  OF  THE  SHOULDER. 

num  and  clavicle.  Below  it  is  thin,  where  it  is  attached  to 
the  sternum  ;  above  it  is  thick,  where  it  is  connected  to  the 
clavicle.  Its  centre  is  thin  and  sometimes  perforated.  Its 
structure  is  fibro-cartilaginous,  and  its  use  seems  to  be  to 
adapt  the  bony  surfaces  to  one  another  as  well  as  to  bind 
them  together. 

The  synovial  membranes  are  two  in  number,  one  on  each 
side  of  the  inter-articular  cartilage.  They  are  found  to 
contain  but  little  synovia,  and  are  strongly  attached  to  the 
adjacent  surfaces. 

Cos  to-clavicular  articulation,  (Fig.  141.) — This  articula- 
tion has  a  short  bundle  of  parallel  ligamentous  fibres, 
called  the  rhomboid  or  inferior  ligament,  running  obliquely 
downward  and  forward  from  the  inferior  surface  of  the 
sternal  end  of  the  clavicle,  to  be  inserted  into  the  upper 
surface  of  the  cartilage  of  the  first  rib.  Posteriorly  it  is 
in  contact  with  the  subclavian  vein,  and  anteriorly  with 
the  subclavian  muscle. 

The  inter-clavicular  ligament  is  placed  at  the  superior  end 
of  the  sternum,  and  extends  from  the  posterior  sternal 
extremity  of  one  clavicle  to  that  of  the  other. 

Scapulo-clavicular  articulation,  (Fig.  221.) — This  articu- 
lation has  a  capsular  ligament  at  the  junction  of  the 
acromion  process  and  clavicle,  whose  fibres  being  thick- 
ened above  and  below,  and  passing  from  one  bone  to  the 
other,  receive  the  name  of  superior  and  inferior  ligaments. 
A  synovial  membrane,  somewhat  indistinct,  is  seen  upon 
the  articular  surface  of  this  joint,  and  occasionaly  an 
inter-articular  cartilage  is  found. 

The  coraco-clavicular  ligament  is  double,  and  consists  of 
the  conoid  and  the  trapezoid. 

The  conoid  is  the  smaller  and  posterior  of  the  two ;  its 
base  is  above  and  attached  to  the  tubercle  on  the  inferior 
surface  of  the  acromial  end  of  the  clavicle.  The  trapezoid 
is  more  anterior  and  external;  it  is  broader,  longer  and 
thinner  than  the  conoid,  and  is  attached  above  to  an 
oblique  line  on  the  under  surface  of  the  clavicle  at  the 
tubercle,  and  below. to  the  root  of  the  coracoid  process. 


704  LIGAMENTS  OF  THE  ARM. 

Between  these  two  ligaments  fatty  and  cellular  structures 
are  seen,  and  occasionally  a  small  bursa. 

FlG  221  The  ligamentumbicorne,  called  also 

the  clavicular  fascia,  springs  from 
the  root  of  the  coracoid  process  and 
divides,  whence  it  receives  the  name 
of  the  bifid  ligament.  One  of  the 
divisions  goes  to  the  first  rib,  the 
other  spreads  over  the  suhclavius 
I  ^  muscle  as  a  fascia,  and  extends  as  far 
forward  as  the  rhomboid  ligament. 
The  ligaments  of  the  scapula  are 
the  coracoid  and  the  triangular. 
(Fig.  221.) 

The  coracoid  is  posterior,  and  is 
stretched  across  the  notch  in  the 
superior  costa  of  the  scapula,  converting  it  into  a  foramen. 
The  triangular  is  anterior,  and  is  also  called  deltoid  or 
coraco-acromial.  It  has  a  broad  origin  from  the  superior 
margin  of  the  coracoid  process.  Its  fibres,  which  are  thin 
and  partially  separated,  converge,  become  thicker,  and  are 
inserted  into  the  acromion  process  where  it  joins  the  clavi- 
cle. This  ligament  forms  an  arch  over  the  shoulder  joint, 
and  is  covered  by  the  deltoid  muscle. 

LIGAMENTS   OF  THE  ARM. 

The  Jiumero-scapular  articulation  contains  the  following 
ligaments  : — 1st,  The  capsular  ligament  (Fig.  221)  ;  2d; 
The  coraco-humeral ;  3d,  The  glenoid. 

The  capsular  ligament  completely  surrounds  this  joint, 
being  attached  above  to  the  margin  of  the  glenoid  cavity, 
and  below  to  the  neck  of  the  humerus.  Above  and  below 
it  is  dense  internally,  and  externally  it  is  thin.  It  is  loose 
and  has  connected  with  it  the  tendons  of  the  four  capsular 

FIG.  221  represents  the  Ligaments  of  the  Shoulder  Joint.  1  Superior  acro- 
mio  clavicular  ligament.  2  Coraco-clavicular  ligament.  3  Coraco-acromial 
ligament.  4  Coracoid  ligament.  5  Capsular  ligament.  6  Coraco-humeral, 
or  ligamentum  adscititium.  7  Tendon  of  the  long  head  of  the  biceps  muscle. 


LIGAMENTS  OF  THE  FOREARM.  705 

muscles,  which  almost  completely  surround  it,  except  a 
small  portion  below  and  internally,  where  it  is  conse- 
quently weaker,  and  where  dislocations  of  this  joint  are 
found  most  commonly  to  occur. 

The  coraco-liumeral,  accessory  ligament,  or  ligamentum 
adscititium  extends  beneath  the  triangular  ligament  down- 
ward and  outward  to  the  greater  tuberosity,  where  it  is 
lost  in  the  capsular.  This  ligament  serves  to  keep  the 
head  of  the  humerus  in  the  glenoid  cavity. 

The  glenoid  ligament  surrounds  the  margin,  and  deepens 
the  glenoid  cavity ;  its  free  edge  is  thin,  but  where  it  con- 
nects with  the  bone  it  is  thick.  The  tendon  of  the  biceps 
partly  contributes  to  this  ligament. 

The  synovial  membrane  lines  the  capsular  ligament  and 
glenoid  surface,  is  reflected  over  the  head  of  the  humerus, 
lines  the  bicipital  groove,  and  forms  a  sheath  around  the 
tendon  of  the  biceps. 

LIGAMENTS  OF  THE    FOREARM. 

The  ligaments  of  the  forearm  are  found  in  the  humero- 
cubital  articulation,  or  the  elbow  joint,  and  are,  1st,  The 
capsular  ligament ;  2d,  External  lateral  or  brachio-radial ; 
3d,  Internal  lateral  or  brachio-ulnar ;  4th,  Coronary  liga- 
ment ;  5th,  Ligamentum  teres. 

The  capsular  ligament  surrounds  the  elbow  joint,  and  is 
connected  above  to  the  lower  end  of  the  humerus,  above 
the  articular  surface,  and  below  to  the  articular  margin  of 
the  ulna  and  neck  of  the  radius. 

The  external  lateral  ligament  extends  from  the  external 
condyle  above  to  the  annular  ligament  surrounding  the 
neck  of  the  radius  below. 

The  internal  lateral  ligament  extends  from  the  internal 
condyle,  expands  and  divides  as  it  descends,  one  portion 
going  to  the  coronoid  process,  the  other  to  the  olecranon. 

Between  the  lateral  ligaments  in  front  and  behind  the 
joint,  the  capsular  ligament  is  thin,  its  fibres  insulated, 
some  taking  an  oblique,  others  a  straight  course,  and  re- 
ceiving the  name  of  accessory  ligaments. 
45 


706 


LIGAMENTS  OF  THE  HAND. 


The  coronary  or  annular  ligament  surrounds  about  two- 
thirds  of  the  neck  of  the  radius,,  and  is  seen  by  opening 
A         FIG.  222.        B       the  joint.     It   extends   from  the 
lesser  sigmoid  cavity  of  the  ulna 
at  its  anterior  margin,  round  the 
radius  to  the  posterior  margin  of 
the  same  cavity. 

The  lig  amentum  teres  or  oblique 
ligament  is  a  round,  short,  fibrous 
cord,  extending  from  the  root  of 
the  coronoid  process  to  the  radius 
below  its  tubercle. 

The  synovial  membrane  is  com- 
mon to  the  three  bones  composing 
the  humero-cubital  articulation, 
as  well  as  the  two  sigmoid  cavi- 
ties and  neck  of  the  radius. 

The  interosseous  ligament  occu- 
pies the  space  between  the  radius 
and  ulna,  being  attached  ,to  the  corresponding  edges  of 
those  bones,  and  perforated  at  its  upper  and  lower  ex- 
tremities. 

LIGAMENTS   OF   THE   HAND. 

The  ligaments  of  the  hand  include  those  of  the  carpus 3 
metacarpus,  and  phalanges. 

LIGAMENTS  OF   THE  CARPUS  OR  WRIST  JOINT. 

The  ligaments  of  the  carpus,  or  wrist-joint,  include  the  cap- 
sular  ligament,  external  lateral  or  radio-carpal,  internal  late- 
ral or  ulna-carpal,  triangular  ligament,  and  annular  ligament. 

The  capsular  ligament  is  connected  above  to  the  articular 

FIG.  222,  A  represents  an  outer  view  of  the  Elbow  Joint.  1  The  humerus. 
2  Ulna.  3  Radius.  4  External  lateral  ligament.  5  Coronary  ligament. 
6  Point  of  attachment  of  the  coronary  ligament.  7  8  Accessory  ligaments. 
9  Interosseous  ligament. 

FIG.  222,  B  represents  an  inner  view  of  the  Elbow  Joint.  ]  Capsular  Liga- 
ment. 2  Internal  lateral  ligament.  3  Coronary  ligament.  4  Ligamentum 
teres.  5  Interosseous  ligament.  6  Internal  condyle. 


LIGAMENTS  OF  THE  HAND. 


TOT 


FIG.  223. 


margin  of  the  lower  ends  of  the  radius  and  ulna,  and  be- 
low to  the  margin  of  the  three  carpal  bones  of  the  first 
row,  the  scaphoides,  lunare,  and  cunei- 
forme,  fibres  being  traced  also  to  the 
bones  of  the  second  row.  This  liga- 
ment is  loose  and  thin,  presenting 
spaces  at  different  points  at  which  the 
synovial  membrane  appears. 

The  external  lateral  ligament  extends 
from  the  styloid  process  of  the  radius 
to  the  scaphoides,  and  on  even  to  the 
trapezium  and  annular  ligament. 

The  internal  lateral  ligament  extends 
from  the  styloid  process  of  the  ulna  to 
the  cuneiform  bone,  and  is  long  and 
round.  Between  the  lateral,  anterior 
and  posterior  ligaments  are  spoken  of, 
which  are  simply  a  thickening  of  the 
capsular  on  the  front  and  back  por- 
tions of  the  joint. 

The  triangular  ligament  is  fibro-cartilaginous,  and  is  con- 
nected with  the  styloid  process  of  the  ulna  and  the  carpal 
end  of  the  radius,  separating  the  ulna  from  the  cuneiform 
bone.  It  is  sometimes  perforated,  and  seems  to  be  a  continu- 
ation of  the  cartilage  on  the  lower  extremity  of  the  radius. 

The  annular  ligament  is  a  strong  fibrous  membrane, 
attached  externally  to  the  scaphoid  and  trapezium,  and 
internally  to  the  cuneiform,  unciform  and  pisiform  bones. 
It  gives  the  arched  form  at  the  wrist,  and  keeps  the  flexor 
tendons  in  their  proper  places,  and  on  the  back  of  the 

FIG.  223  represents  the  Ligaments  of  the  Wrist  Joint.  1  Interosseous  liga- 
ment. 2  Radio-ulnar.  3  Capsular  ligament.  4  External  lateral.  5  Internal 
lateral  ligament.  6  Capsular  ligament  of  the  carpal  bones.  7  Os-pisiforme. 

8  Ligaments  joining  the  metacarpal   with  the   second   row  of  the  carpus. 

9  Capsular  ligament  of  the  carpo-metacarpal  joint  of  the  thumb.    10  Capsular 
ligament  of  the  metacarpo-phalangeal  joint  of  the  thumb.    11  External  lateral 
ligament  of  the  same  joint.     12  Capsular  ligament  of  the  metacarpo  phalan- 
geal  joint  of  the  index  finger.    13  13  Lateral  ligaments  of  similar  articulations. 
14  Inferior  palmar  ligaments.     15  Capsular  and  lateral  ligaments  of  the  last 
joint  of  the  thumb. 


708  LIGAMENTS  OF  THE  METACARPUS. 

wrist  it  is  called  ligamentum  carpi  dorsale,  and  extends  from 
the  styloid  edge  of  the  radius  to  the  styloid  edge  of  the  ulna. 

The  lower  head  of  the  ulna  is  received  into  the  sigmoid 
cavity  of  the  radius,  constituting  the  lower  radio-ulnar 
articulation,  and  is  retained  there  by  a  loose  synovial  mem- 
brane termed  the  sacciform  ligament. 

The  synovial  membrane  covers  the  articular  surface  of  the 
bones  and  the  inter-articular  fibro-cartilage,  and  is  reflected 
upon  the  inner  surface  of  the  capsular  ligament. 

The  first  and  second  rows  of  the  carpal  bones,  except  the 
pisiforme,  are  united  by  a  capsular  ligament,  extending 
from  one  row  to  the  other,  and  seeming  to  be  a  continua- 
tion of  the  radio-carpal ;  it  is  also  thickened  laterally  by 
external  and  internal  lateral  ligaments,  the  former  extending 
from  the  scaphoides  to  the  trapezium,  the  latter  from  the 
cuneiform  to  the  unciform. 

The  pisiform  bone  articulates  with  the  cuneiform  by  a 
separate  cartilage,  synovial  membrane  and  proper  capsular 
ligament.  Interosseous  ligaments  are  found  connecting 
also  the  several  carpal  bones,  and  ligamentous  fibres,  run- 
ning transversely,  called  from  their  position  palmar  and 
dorsal  ligaments. 

The  synovial  membrane  extends  from  the  first  carpal  row 
to  the  second  and  down  to  the  metacarpal  bones  ;  it  also 
dips  down  between  the  bones  of  the  carpus  and  lines  the 
inner  surface  of  the  capsular  ligament,  and  is  thus  common 
to  all  the  carpal  and  metacarpal  articulations,  except  the 
cuneiform  and  pisiforme,  the  trapezium  and  metacarpal 
bone  of  the  thumb,  and  the  space  between  the  third  and 
fourth  metacarpal  bones,  all  of  which  have  distinct  synovial 
membranes. 

LIGAMENTS  OF  THE  METACARPUS,  (Fig.  223.) 

These  belong  to  the  carpo-metacarpal  articulation,  and 
include  the  dorsal  and  the  palmar  ligaments. 

The  dorsal  pass  directly  from  the  carpal  to  the  base  of 
the  metacarpal  bones,  the  latter  being  also  connected  by 
transverse  fibres. 


MUSCLES  OP  THE  SHOULDER.  709 

The  palmar  pursue  a  similar  course  with  the  dorsal,  but 
are  not  so  strong. 

The  metacarpal  bones  have  also  strong  lateral  connec- 
tions by  transverse  ligaments  where  their  surfaces  come  in 
contact.  The  synovial  membrane  is  a  prolongation  from 
that  of  the  carpus. 

The  phalangeal  extremity  of  the  metacarpal  bones  form 
the  metacarpo-phalangeal  articulation,  and  include :  1.  An- 
terior ligaments,  or  capsular ;  2.  Lateral  ligaments. 

The  anterior  ligaments  are  flat  fibro-cartilaginous  bands, 
which  run  transversely  and  connect  the  sides  of  the  heads 
of  the  metacarpal  bones. 

The  lateral  ligaments  are  thickenings  of  the  capsular 
laterally,  and  extend  from  the  sides  of  the  metacarpal 
bones,  and  descend  as  strong,  short  cords  to  be  attached  to 
the  sides  of  the  upper  ends  of  the  first  phalanges.  A 
synovial  membrane  belongs  to  this  articulation. 

LIGAMENTS  OF  THE  PHALANGES  OR  FINGERS,    (Fig.   223.) 

Each  finger  has  one  anterior  ligament  and  two  lateral 
ligaments. 

The  anterior  ligament  corresponds  precisely  to  the  meta- 
carpo-phalangeal, just  described ;  and  the  lateral  go  from 
phalanx  to  phalanx  on  each  side.  There  is  also  the  usual 
synovial  membrane. 


CHAPTEK  II. 

ACTIVE  ORGANS  OF  THE  SUPERIOR  EXTREMITIES. 
SECTION    I. 

MUSCLES  OF  THE  SUPERIOR  EXTREMITY. 

THESE  muscles  are  arranged  into  those  of  the  shoulder, 
arm,  forearm,  and  hand. 

MUSCLES  OF  THE  SHOULDER. 

These  comprise  the  deltoid,  supra-spinatus ,  infra-spinor 
tus,  teres-minor,  teres-major,  and  sub-scapularis. 


710  MUSCLES  OP  THE  SHOULDER. 

Deltoid — A,  delta,  *t8oj,  likeness,  (Figs.  150,167.) — Dissec- 
tion.— Make  the  first  incision  along  the  posterior  third  of 
the  clavicle,  the  acromial  margin,  and  spine  of  the  scapula; 
the  second  from  the  acromion  process,  along  the  middle  of 
the  humerus,  and  commence  the  dissection  from  this  last 
incision,  turning  off  the  integuments  internally  and  exter- 
nally with  the  cellular  structure,  when  this  muscle  will  he 
exposed.  It  arises  from  the  external  third  of  the  clavicle, 
fleshy;  from  the  outer  margin  of  the  acromion  process,  ten- 
dinous and  fleshy ;  and  from  the  whole  of  the  inferior  edge 
of  the  spine  of  the  scapula.  It  is  inserted  on  the  outer  side 
of  the  humerus,near  its  centre,  in  a  triangular  rough  surface. 

This  muscle  is  triangular  in  shape,  thick  and  strong,  cov- 
ers the  shoulder-joint,  and  gives  it  its  rotundity.  The  fibres 
converge — the  anterior  descending  obliquely  backward,  the 
posterior  forward,  and  the  middle  directly  downward,  the 
three  presenting  so  many  separate  parts  or  muscles. 

Function. — To  raise  the  arm.  and,  according  to  the  direc- 
tion of  the  fibres,  to  draw  it  either  forward  or  backward. 
Beneath  the  superior  portion  of  this  muscle,  extending 
under  the  acromion  process,  is  seen  a  large  bursa. 

Supra-spinatus — supra,  above ;  spina,  the  spine — (Fig. 
150.)  By  turning  down  the  deltoid  this  muscle  is  seen  ;  it 
arises  fleshy  from  the  whole  of  the  supra-spinal  fossa,  also 
from  a  strong  fascia  covering  it ;  it  then  passes  under  the 
acromion  process,  ending  in  a  strong  tendon,  which  is 
firmly  attached  to  the  capsular  ligament,  and  is  inserted 
into  the  inner  face  of  the  greater  tuberosity  of  the  humerus. 

Function. — To  raise  the  arm  and  turn  it  outward ;  also 
to  strengthen  the  capsular  ligament,  and  to  draw  it  from 
"between  the  humerus  and  glenoid  cavity,  in  the  elevation 
of  the  arm. 

Infra  spinatus — infra,  beneath ;  spina,  spine — (Fig.  150,) 
arises  from  the  whole  of  the  dorsum  of  the  scapula  below 
its  spine,  from  the  margins  of  the  bone,  and  from  the 
aponeurosis  covering  it,  forming  a  flat,  triangular  muscle. 
Its  fibres  converge,  the  superior  going  horizontally,  the 
inferior  ascending  obliquely  forward,  to  a  strong  central 


MUSCLES  OF  THE  SHOULDEK.  711 

tendon,  which  goes  under  the  acromion  process,  adheres  to 
the  capsular  ligament,  and  is  inserted  into  the  middle  face 
of  the  greater  tuherosity  of  the  humerus. 

Function. — To  roll  the  os-humeri  outward  and  backward. 
To  strengthen  the  capsular  ligament  and  to  draw  it  out  of  the 
joint,  in  the  outward  movements  of  the  arm.  There  is  also 
a  hursa  between  the  tendon  of  this  muscle  and  the  scapula- 
Teres  minor — teres,  round — (Fig.  150,)  is  a  small  and 
narrow  muscle,  and  arises  from  the  inferior  costa  of  the 
scapula  at  the  lower  margin  of  the  infra  spinatus,  is  in- 
separably attached  to,  and  in  fact  forms  part  of  this  latter 
muscle.  It  extends  from  the  cervix  to  about  an  inch  of 
the  inferior  angle,  and  adhering  to  the  capsular  ligament, 
is  inserted  tendinous  and  fleshy  into  the  outer  face  of  the 
great  tuberosity  of  the  humerus. 

Function. — To   rotate   the   arm   outward,   and   draw   it 
downward  and  backward. 

The  teres  major  (Fig.  224)  is  a  flat  muscle,  and  arises 
from  the  inferior  angle  of  the  scapula  upon  its  rough  flat 
surface.  Forming  a  thick  fleshy  belly,  it  ascends  forward 
and  outward,  and  terminates  on  the  inner  side  of  the  arm 
in  a  broad  thin  tendon,  which  is  inserted  along  with  the 
tendon  of  the  latissimus  dorsi  into  the  inner  or  posterior 
edge  of  the  bicipital  groove.  The  tendon  of  the  teres 
FIG.  224.  major  is  posterior,  and  extends  lower 

down  the  arm  than  the  latissimus. 

Function. — To  roll  the  arm  in- 
ward, and  draw  it  backward  and 
downward. 

The  sub-scapularis  (sub,  under; 
scapula,  shoulder-blade)  is  a  broad 
triangular  muscle,  which  arises  from  the  whole  of  the 
venter,  and  the  superior  and  inferior  costse  of  the  scapula. 
Its  fibres  converge  to  the  neck  of  the  scapula,  pass  below 
the  coracoid  process,  adhere  to  the  inferior  part  of  the 
capsular  ligament,  and  terminate  in  a  strong  tendon, 

FIG.  224  represents  the  Muscles  of  the  Shoulder.     1  Deltoid     2   Subscapu- 
laris.     3  Teres  major.     4  Triceps. 


712 


MUSCLES  OF  THE  ARM. 


which  is  inserted  into  the  lesser  tuberosity  of  the  humerus. 
Between  the  tendon  of  this  muscle  and  the  neck  of  the 
scapula,  a  large  bursa  communicating  with  the  joint  is 
seen ;  also  another  smaller  one  between  the  tendon  and 
capsular  ligament.  Function. — To  roll  the  arm  inward  and 
downward. 

MUSCLES   OF   THE  ARM,    (Fig.    225.) 

These  comprise  the  biceps  flexor  cubiti, 
cwaco-bradiialis ,  brachialis  anticus,  tri- 
ceps extensor  cubiti,  and  anconeus. 

Biceps  flexor  cubiti.  —  Dissection. — 
Make  an  incision  along  the  middle  an- 
terior region  of  the  humerus  down  to 
the  elbow-joint,  which  cross  by  a  trans- 
verse incision  at  the  middle  of  the  arm, 
turn  aside  the  integuments  and  fascia, 
11  and  this  muscle  will  be  exposed.  It  is 
superficial  and  forms  the  swell  along  the 
front  part  of  the  arm.  It  arises  by 
two  heads ;  the  internal  or  short  head 
comes  from  the  coracoid  process  in  com- 
mon with  the  coraco-brachialis  ;  the  ex- 
ternal or  long  head  arises  by  a  round 
tendon  from  the  upper  part  of  the  gle- 
noid  cavity  of  the  scapula,  goes  through 
the  joint,  over  the  head  of  the  humerus, 
surrounded  by,  but  external  to,  the  sy- 
novial  membrane,  and  then  descends 
through  the  groove  between  the  tuberos- 
ities  of  the  humerus,  between  the  tendons 

FIG.  225  represents  the  Muscles  on  the  front  of  the  Arm.  1  Clavicle. 
2  Coracoid  process.  3  Acromion  process.  4  Head  of  the  humerus.  5  Ten- 
don of  the  biceps.  6  Ligamentum  adscititium.  7  Insertion  of  pectoralis  major. 
8  Long  head  of  the  biceps.  9  Insertion  of  the  deltoid.  10  Insertion  of  pec- 
toralis minor.  11  Coraco  brachialis.  12  Short  head  of  biceps.  13  Latissi- 
mus  dorsi.  14  Triceps.  15  Body  of  the  biceps.  16  External  part  of  triceps. 
17  Brachialis  anticus.  18  Origin  of  the  flexor  muscles.  19  Insertion  of  bra- 
chialis an  ticus.  20  Tendon  of  the  biceps.  21  Bicipital  aponeurosis.  22  Flexor 
carpi  radialis.  23  Palmaris  longus.  24  Supinator  radii  longus. 


MUSCLES  OF  THE  ARM. 


713 


of  the  latissimus  dorsi  and  teres  major  behind,  and  the  pec- 
toralis  major  in  front.  Becoming  fleshy  it  unites  with  the 
belly  of  the  short  head,  at  first  loosely  by  cellular  tissue,  but 
a  little  below  the  middle  of  the  arm  the  two  heads  become 
inseparably  united  to  form  a  thick  fleshy  belly,  which  a 
little  above  the  elbow-joint  ends  in  a  flat  tendon,  passing 
in  front  of  the  joint  to  be  inserted  into  the  posterior  part 
of  the  tubercle  of  the  radius. 

A  bursa  is  placed  between  the  tendon  and  the  tubercle, 
and  from  the  ulnar  side  of  the  tendon  proceeds  the  bicipital 
aponeurosis,  which,  passing  over  the  brachial  artery  and 
nerve,  joins  the  general  fascia  of  the  forearm. 

Function. — To  flex  the  forearm.  This  muscle  is  related 
with  the  brachial  artery,  which  see. 

Coraco-brachialis ,  (Fig.  225.) — Arises  from  the  coracoid 
process,  in  common  with  the  short  head  of  the  biceps,  ten- 
dinous and  fleshy.  It  descends,  connected  with  the  short 
head  about  three  or  four  inches,  along  the  inner  arm  to  be 
inserted  tendinous  and  fleshy  into  the  inner  side  of  the 
humerus,  about  its  centre,  and  by  an  aponeurosis  into  the 
ridge  leading  to  the  internal  condyle. 

Function. — To  raise  the  arm  and  draw  it  forward ;  it  can 
also  turn  it  outward.  The  musculo-cutaneous  nerve  pene- 
trates this  muscle.  It  is  related  with  the  brachial  artery, 
which  see. 

The  brachialis  anticus  or  internus  (Fig.  225)  arises  on 
either  side  of  the  insertion  of  the  deltoid  by  two  fleshy 
slips,  which  uniting  descend,  occupying  the  whole  front  of 
the  lower  part  of  the  humerus,  to  be  inserted  into  the  coro- 
noid  process  of  the  ulna  by  a  strong  tendon.  This  tendon 
is  between  the  supinator  radii  longus  and  pronator  radii 
teres,  and  passes  beneath  the  tendon  of  the  biceps  and  over 
the  elbow-joint. 

Function. — To  bend  the  forearm  and  strengthen  the 
elbow-joint.  This  muscle  also,  as  the  biceps,  has  a  relation 
with  the  brachial  artery,  which  see. 

Triceps  extensor  cubiti — *?"*  *«$o3uu$,  three  heads — (Fig 
226.) — This  is  a  three-headed  muscle,  large  and  powerful, 


714 


MUSCLES   OF   THE  FOREARM. 


FIG.  226. 


and  covering  the  whole  hack  part  of  the  humerus.  It 
arises  hy  its  long  head  from  the  lower  margin  of  the  cervix 
scaptila3  by  a  flat,  short  tendon.  The  second  head  comes 
from  the  outer  and  hack  part  of  the 
humerus,  just  below  the  greater  tu- 
berosity.  The  third  head)  called 
brachialis  externus,  but  more  pro- 
perly internus,  arises  fleshy  from 
the  inner  side  of  the  humerus,  near 
the  insertion  of  the  teres  major. 
The  three  heads  unite  to  form  one 
muscle,  which  adheres  strongly  to 
the  bone,  and,  ending  in  a  broad 
tendon,  is  inserted  into  the  posterior 
part  of  the  olecranon  process.  A 
bursa  is  seen  between  the  tendon 
and  olecranon.  Function. — To  ex- 
tend the  forearm. 

The  Anconeus — ayxcov,   the  elbow, 
(Fig.  230,)  arises  tendinous  from  the 
external  condyle  of  the  os-humeri. 
It  is  concealed  partly  by  the  triceps, 
and  appears  to  be  a  portion  of  this 
muscle.    It  is  inserted  into  the  ridge  of  the  upper  extremity 
of  the  ulna  connected  with  the  olecranon. 
function. — To  extend  the  forearm. 

MUSCLES   OF   THE   FOREARM. 

These  comprise  two  divisions  :  1st,  Flexors  and  Prona- 
tors  on  the  anterior  forearm ;  2d,  Supinators  and  Extensors 
on  the  posterior. 

The  first  division  includes  eight  muscles,  the  pronator 
radii  teres,  flexor  carpi  radialis,  palmaris  longus,  flexor  carpi 
ulnaris,  flexor  digitorum  sublimis  perforatus ,  flexor  digitorum 
pro/undus  perforans,  flexor  longus  polticis,  pronator  quad- 
ratus. 

FIG.  226  represents  the  Triceps  Muscle,  a  External  head  of  the  triceps.  6  Its 
long  head,  c  Its  short  head,  d  Olecranon  process,  e  Radius.  /  Capsular 
ligament. 


MUSCLES   OF   THE   FOREARM. 


715 


Pronator  radii  teres,  (Fig.  227-)— Dissection.— Make  an 
incision  through  the  integuments  along  the  centre  of  the 
forearm,  from  the  elbow  to  the  wrist ;          FIG.  227. 
make  a  second  incision  transversely  about 
the  middle  ;  turn  off  the  integuments  to 
the  fascia,  which  latter  dissect  off  sepa- 
rately, and  this  muscle  will  be  exposed. 

It  arises  fleshy  from  the  internal  con- 
dyle,  and  tendinous  from  the  coronoid 
process  of  the  ulna ;  its  course  is  obliquely 
across  the  forearm  to  be  inserted  mostly 
tendinous  into  the  middle  of  the  back 
part  of  the  radius.  .Function. — To  pronate 
the  hand  by  rolling  the  radius  inward. 

The  flexor  carpi  radialis  (Fig.  22*7) 
arises  tendinous  from  the  inner  condyle, 
and  fleshy  from  the  upper  part  of  the 
ulna,  the  interrhuscular  ligaments,  and 
brachial  fascia,  forming  a  thick  fleshy 
belly  upon  the  ulnar  side  of  the  last  mus- 
cle, and  descends  obliquely  outward  be- 
neath the  anterior  annular  ligament, 
through  a  groove  in  the  os-trapezium,  to 
be  inserted  into  the  fore  part  of  the  base 
of  the  metacarpal  bone  of  the  index  finger.  A  bursa  is 
seen  between  the  tendon  and  os-trapezium.  Function. — To 
flex  the  hand  on  the  wrist. 

This  muscle  is  related  with  the  radial  artery,  which  see. 

The  palmaris  longus  (Fig.  227)  arises  from  the  inner 
condyle  by  a  slender  tendon,  and  fleshy  from  the  inter- 
muscular  ligaments.  Forming  a  short  belly,  it  ends  in  a 
long  slender  tendon,  which  is  inserted  into  the  anterior 
annular  ligament  and  palmar  aponeurosis. 

FIG.  227  represents  the  Superficial  Muscles  on  the  front  of  the  Forearm. 
1  Inferior  portion  of  the  Biceps.  2  Brachialis  anticus.  3  Triceps.  4  Pro- 
nator radii  teres.  5  Flexor  carpi  radialis.  6  Palmaris  Longus.  7  Flexor 
sublimis  perforatus.  8  Flexor  carpi  ulnaris.  9  Fascia  palmaris.  10  Pal- 
maris-brevis  muscle.  11  Abductor-pollicis  manus.  12  Flexor-brevis  pollicis 
raanus.  13  Supinator  radii  Longus.  14  Extensor-ossis  metacarpi  pollicis. 


Y16 


MUSCLES  OF  THE  FOREARM. 


Function. — To  flex  the  hand  and  make  tense  the  palmar 
aponeurosis.  This  muscle  is  sometimes  absent. 

The  flexor  carpi  ulnaris  (Fig.  22*7)  arises  from  the 
inner  condyle  tendinous,  from  the  inner  side  of  the  olecra- 
non  process  fleshy  and  tendinous,  from  the  ridge  upon  the 
inner  side  of  the  ulna  nearly  its  whole  length,  and  from 
the  fascia  of  the  forearm.  It  forms  a  round  tendon  which 
is  inserted  into  the  pisiform  bone,  and  base  of  the  metacar- 
pal  bone  of  the  little  finger. 

Function. — To  flex  the  hand,  and  bring  it  towards  the 
ulna.  A  bursa  is  seen  between  the  tendon  and  os  pisiforme* 
It  is  related  with  the  ulnar  artery,  which  see. 

Flexor  digitorum  sublimis  perforatus,  (Fig.  227.)  Dis- 
section.— Kemove  the  superficial  muscles,  and  the  flexor 
sublimis  is  brought  to  view. 

It  arises  from  the  inner  condyle  and  coronoid  process, 
tendinous  and  fleshy — fleshy  from  the  tubercle  of  the  radius 
and  for  three  or  four  inches  below  the  tubercle.  Before  the 
muscle  reaches  the  wrist  it  divides  into  four  tendons  which 
pass  to  the  palm  of  the  hand  beneath  the  anterior  annular 
ligament,  and  then  diverge  to  be  inserted  into  the  second 
phalanx  of  each  finger.  The  tendons  of  this  muscle  are 
enclosed  in  a  strong  sheath,  and  at  their  intersection  split 
into  two,  through  which  the  tendon  of  the  perforans  passes. 

Function. — To  bend  the  second  phalanges  on  the  first.  A 
large  bursa  surrounds  the  tendons  of  this  muscle  beneath 
the  annular  ligament. 

The  flexor  digitorum  profundus  perforans  (Fig.  228) 
arises  beneath  the  sublimis,  from  the  upper  anterior  sur- 
face of  the  ulna  and  inner  portion  of  the  interosseous  liga- 
ment, fleshy — also  fleshy  from  the  coronoid  process  of  the 
ulna  and  inner  side  of  the  olecranon  process.  A  thick 
muscle  is  formed,  which  at  the  lower  part  of  the  arm 
divides  into  four  flat  tendons,  which  go  beneath  the  annular 
ligament,  enter  the  ligamentous  sheaths  on  the  fingers, 
pass  through  the  slits  in  the  perforatus,  and  are  inserted 
into  the  last  phalanx  of  each  finger.  Function. — To  bend 
the  last  phalanges,  and  with  the  sublimis  the  hand. 


MUSCLES  OF  THE  FOREARM. 


UT 


The  flexor  longus  pollicis  (Fig.  228)  arises,  fleshy,  be- 
neath the  flexor  sublimis  from  the  front  part  of  the  ra- 
dius, below  its  tubercle,  for  about  two-thirds  of  its  extent, 
and  from  the  radial  portion  of  the  inter-          FIG.  228. 
osseous   ligament.     It    also   has   a   ten- 
dinous origin  from  the   inner   condyle. 
Its  tendon  passes  beneath  the  annular 
ligament,  and  between  the  two  heads  of 
the  short  flexor  and  sesamoid  bones,  to  be 
inserted  into  the  second  phalanx  of  the 
thumb.    A  bursa  is  seen  in  connection 
with  the  tendon  of  this  muscle. 

Function. — To  bend  the  last  phalanx 
of  the  thumb. 

The  pronator  quadratus  (Fig.  228) 
arises  from  the  anterior  front  surface  of 
the  lower  extremity  of  the  ulna,  broad, 
tendinous  and  fleshy,  passes  transversely, 
and  is  inserted  into  the  lower  front  sur- 
face of  the  radius.  It  is  a  small,  square 
muscle,  concealed  by  the  flexor  longus 
pollicis  and  flexor  profundus. 

Function. — To  pronate  the  hand  by 
rolling  the  radius  inward. 

The  muscles  on  the  posterior  part  of 
the  forearm  include  the  supinators  and  extensors,  and  com- 
prise ten  muscles,  viz  :  the  supinator  radii  longus,  exten- 
sor carpi  radialis  longior,  extensor  carpi  radialis  brevior, 
extensor  carpi  ulnaris,  extensor  digitorum  communis,  supi- 
nator radii  brevis,  extensor  ossis  metacarpi  pollicis  manus, 
extensor  minor  pollicis,  extensor  major  pollicis,  indicator. 

Supinator  radii  longus. — Dissection. — Make  an  incision 
along  the  middle  of  the  back  part  of  the  arm  and  forearm. 
Make  a  second  incision  transversely  about  the  middle  of 

FIG.  228  represents  the  deep  muscles  on  the  front  of  the  Forearm,  a  Internal 
lateral  ligament,  b  Capsular  ligament,  c  Coronary  ligament,  d  Flexor  pro- 
fundus perforans.  t  Flexor  longus  pollicis.  /Pronator  quadratus.  g  Adductor 
pollicis  manus.  /i  Lumbricales.  i  Interossei. 


MUSCLES  OF  THE  FOREARM. 


the  forearm,  turn  aside  the  integuments  and  this  muscle 
will  be  exposed. 

It  arises  tendinous  and  fleshy  from  the  ridge  leading  to 
the  external  condyle,  commencing  a  little  below  the  inser- 
tion of  the  deltoid,  also  from  the  inter-muscular  ligaments- 
FIG.  229.  A   thick   muscle   is   formed,    which  de- 

scends along  the  outer  part  of  the  elbow, 
and  at  the  middle  of  the  fore-arm  termi- 
nates in  a  flat  tendon,  which  is  inserted 
upon  the  styloid  side  of  the  radius. 

Function. — To  supinate  or  turn  the 
palm  of  the  hand  upward  by  rolling  the 
radius  outward. 

Extensor  carpi  radialis  longior  (Fig. 
229)  arises  from    the  external  ridge  of 
the  os  humeri,  between  the  external  con- 
dyle  and  supinator  longus,  tendinous  and 
fleshy.     A  thick,  short  belly  is  formed^ 
which   about  the  middle  of  the  radius 
ends  in  a  flat  tendon,  which  passes  under 
the  posterior  annular  ligament  and  over 
the  wrist,  to  be  inserted  into  the  poste- 
rior part  of  the  root  of  the  metacarpal 
bone  of  the  fore-finger.     A  bursa  is  seen 
surrounding  the  tendon  of  this  muscle 
under  the  annular  ligament,  and  another 
at  its  insertion. 
Function. — To  extend  the  wrist  and  hand. 
Extensor   carpi  radialis  brevior  (Fig.    229)  arises  from 
the  external  condyle  and  external  lateral  ligament,  tendi- 
nous and  fleshy.     A  thick  fleshy  belly  is  formed,  situated 

FIG.  229  represents  the  muscles  on  the  back  of  the  forearm,  a  Inferior 
portion  of  the  biceps,  b  Inferior  portion  of  the  brachialis  anticus.  c  Inferior 
portion  of  the  triceps,  d  Supinator  radii  longus.  e  Extensor  carpi  radialis 
longior.  /Extensor  carpi  radialis  brevior.  g  Tendinous  insertions  of  these 
two  latter  muscles,  h  Extensor  communis  digitorum.  i  Auricularis,  a  portion 
of  extensor  communis.  j  Extensor  carpi  ulnaris.  fcAnconeus.  /  Flexor  carpi 
ulnaris.  m  Extensor  minor  pollicis.  n  Extensor  major  pollicis.  o  Posterior 
annular  ligament. 


MUSCLES  Of  THE  FOREARM.  T19 

beneath  the  last  muscle,  which  about  the  middle  of  the 
forearm  ends  in  a  flat  tendon,  which  passes  under  the  pos- 
terior annular  ligament,  in  the  same  groove  with  the  last 
muscle,  and  is  inserted  into  the  root  of  the  metacarpal  bone 
of  the  second  or  middle  finger,  on  its  back  part. 
Function. — To  extend  the  wrist  and  hand. 
The    extensor    digitorum    communis    (Fig.    229)    arises 
from  the  external  condyle,  intermuscular  ligament,  and 
fascia,  tendinous   and   fleshy.     It  descends  to   about   the 
middle  of  the  forearm,  where  it  ends  in  four  tendons  which 
pass  in  a  common  groove  of  the  radius  under  the  posterior 
annular  ligament,  and  on  the  back  of  the  hand  diverge  to 
the  roots  of  the  fingers,  where  they  are  connected  by  cross 
slips,  from  whence  they  expand  over  the  whole  posterior 
part  of  all  the-  phalanges  of  the  fingers.     The  portion  of 
this  muscle  going  to  the  little  finger  receives  .the  name  of 
auricularis.    A  bursa  is  connected1  with  the  tendons  of  this 
muscle  under  the  posterior  annular  ligament,  and  can  be 
traced  along  these  tendons  to  the  base  of  the  first  phalanges. 
Function. — To  extend  all  the  fingers. 
The    extensor   carpi  ulnaris  (Fig.  229)  arises  tendinous 
from  the  external  condyle,  and  fleshy  from  the  intermus- 
cular ligament  and  fascia;   also  fleshy  from  the  back  part 
of  the  ulna.   It  then  descends,  crossing  obliquely  the  upper 
part  of  the  radius  and  ulna,  to  end  in  a  strong  tendon, 
which  passes  through  a  groove  on  the  back  of  the  ulna,  to 
be  inserted  into  the  base  of  the  metacarpal  bone  of  the  little 
finger.     A  bursa  is  seen  where  the  tendon  passes  through 
the  groove  of  the  ulna. 

Function. — To  extend  the  wrist  and  hand. 
The   supinator  radii  brevis  (Fig.  230)  arises  tendinous 
and  fleshy  from  the  external  condyle,  external  lateral  and 
coronary  ligaments,  and   from  a  ridge  on  the  outer  and 
upper  part  of  the  ulna.     On  removing  the  superficial  mus- 
cles attached  to  the  external  condyle,  it  is  seen  surrounding 
the  outer  and  upper  part  of  the  radius,  and  inserted  into 
the  tubercle  of  the  radius,  and  into  the  oblique  ridge  lead- 
ing to  the  insertion  of  the  pronator  teres.- 
Function. — To  roll  the  radius  outward. 


720 


MUSCLES  OF  THE  FOREARM. 


Extensor  ossis  metacarpi  pollicis  manus,    (Fig.    230.) — 
This  muscle,  called  also  extensor  primi  pollicis,  arises  fleshy 
from  the  posterior  part  of  the  ulna,  just  below  the  anconeus 
from  the  interosseous  ligament,  and  from  the  posterior  part 
FIG.  230.          of  the  radius,  below  the  supinator  brevis. 
It  ends  in  a   round  tendon  which  goes 
over  the  radial  extensors,  and  through  a 
groove  on  the  styloid  side  of  the  radius, 
to  be  inserted  into  the  os-trapezium  and 
into  the  base  of  the  metacarpal  bone  of 
the  thumb.     A  bursa  is  seen  where  the 
tendon  passes  through  the  groove  of  the 
radius.     Function. — To  extend  the  meta- 
carpal bone  of  the  thumb. 

The  extensor  minor,  or  secundi  pollicis, 
(Fig.  230,)  arises,  tendinous  and  fleshy, 
from  the  posterior  part  of  the  ulna,  below 
its  middle,  and  from  the  interosseous 
ligament  and  radius.  It  descends  and 
passes  through  the  same  groove  of  the 
radius  with  the  last  muscle,  and  is  in- 
serted into  the  posterior  part  of  the  first 
phalanx  of  the  thumb.  Function. — To 
extend  the  first  phalanx  of  the  thumb. 

The  extensor   major,  or  tertii  pollicis, 
(Fig.  230,)  arises,  above  the  middle  of 
the  ulna  on  its  posterior  part,  from  the  interosseous  liga- 
ment, and  from  the  back  of  the  radius.     It  ends  in  a  tendon 
which  passes  through  a  separate  groove  of  the  radius,  and 
goes  to  be  inserted  into  the  last  phalanx  of  the  thumb.     A 
synovial  membrane  supplies  its  tendon  at  the  wrist. 
Function. — To  extend  the  last  phalanx  of  the  thumb. 
The  indicator  (Fig.  230)  arises  tendinous  and  fleshy  from 

FIG.  230  represents  the  Deep  Muscles  on  the  back  of  the  Forearm,  a  Inferior 
portion  of  the  humerus.  6Olecranon  process,  c  Body  of  the  ulna,  d  Anco- 
neus. e  Supinator  radii  brevis.  /  Extensor  ossis  metacarpi  pollicis.  g  Exten- 
sor minor  pollicia.  h  Extensor  major  pollicis.  i  Indicator,  j  First  dorsal 
interossei. 


MUSCLES  OF  THE   HAND. 

the  middle  of  the  back  part  of  the  ulna.  It  is  a  small 
muscle,  concealed  by  the  extensor  ulnaris  and  communis. 
It  ends  in  a  tendon  which  passes  along  the  same  groove 
with  the  extensor  communis,  beneath  the  annular  ligament, 
and  is  inserted  with  the  tendon  of  that  muscle  into  the 
back  part  of  the  second  and  third  phalanges  of  the  fore 
finger.  Function. — To  extend  the  fore  finger.* 

MUSCLES  OF  THE  HAND. 

Dissection. — Make  an  incision  from  the  wrist  along  the 
middle  of  the  palm  to  the  base  of  the  fingers ;  make  a  second 
incision  crossing  the  first  transversely  about  its  centre,  now 
reflect  the  integuments  to  either  side,  which  will  lead  to  the 

*  During  the  dissections  in  the  winter  of  1849-50,  in  the  Baltimore  Col- 
lege of  Dental  Surgery,  a  muscle  was  seen  in  connection  with  the  indicator 
which  seems  to  be  entirely  new,  or  at  least  not  present  in  the  dissections  of 
anatomical  writers,  as  we  cannot  find  that  they  make  any  mention  of  it.  We 
have  thought  the  name  of  Extensor  Jlccessorius  Jndicis  not  inappropriate.  We 
will  quote  the  explanation  given  of  this  muscle,  from  the  April  number,  1850, 
of  the  Medical  Examiner.  "  It  had  its  origin  on  the  right  hand  by  a  delicate» 
tendinous  membrane,  from  the  radio-carpal  articulation,  behind  the  posterior 
annular  ligament,  and  in  the  same  groove  with,  and  posterior  to  the  tendons  of 
the  extensor  communis  and  indicator,  forming 
a  fleshy  bulb  nearly  the  size  of  the  plantaris 
of  the  leg.  It  soon,  however,  divided  into  two 
bellies— the  one  short  and  attached  or  inserted 
by  a  delicate  tendon,  into  the  tendon  of  the  in- 
dicator, near  the  base  of  the  metacarpal  bone 
of  the  fore  finger — the  other  larger,  and  con- 
nected also  to  the  indicator,  but  near  the 
articulation  of  the  metacarpal  bone  with  the 
first  phalanx  of  the  fore  finger,  and  also  by  a 
narrow  tendon,  as  seen  in  the  drawing.  On 
the  left  hand  the  muscle  had  but  one  belly, 
which  ended  in  a  tendon  having  a  similar  at- 
tachment and  resemblance  to  the  larger  belly 
upon  the  right.  Its  function  seems  evidently 
to  assist  the  indicator  in  the  extension  of  the 
fore  finger.  Fig.  231  exhibits  the  muscle  as 
seen  from  the  dissection. 

"  a  a  Posterior  annular  ligament  laid  open.  6  Origin  of  the  new  muscle .  c  Its 
smaller  belly.  <Hts  greater  belly,  h  Tendinous  insertion  of  smaller  belly. 
g Tendinous  insertion  of  larger  belly,  e  Indicator.  /Extensor  communis 
turned  to  one  side  to  expose  the  origin  of  the  new  muscle,  i  Extensor  longus 
pollicis." 

46 


722 


MUSCLES  OF  THE  THUMB. 


FIG.  232. 


exposure  of  most  of  the  muscles  of  the  hand.     For  the  fin- 
gers, extend  the  incision  along  the  middle  line  of  each. 

The  muscles  of  the  hand  are  arranged  into  those  of  the 
thumb,  the  little  finger,  and  its  palmar  and  dorsal  muscles. 

MUSCLES  OF  THE    THUMB. 

The  abductor  pollicis  (Fig.  227)  arises  from  the  anterior 
annular  ligament,  trapezium,  and  scaphoides,  thin  and 

broad,  and  is  inserted  into  the 
radial  side  of  the  base  of  the 
first  phalanx  of  the  thumb. 

Function. — To  draw  the 
thumb  from  the  fingers. 

The  opponens  pollicis 
(flexor  ossis  metacarpi  polli- 
cis, Fig.  232)  arises  from  the 
annular  ligament  and  trape- 
zium, tendinous  and  fleshy,  is 
beneath  the  last,  and  is  in- 
serted into  the  radial  margin 
of  the  metacarpal  bone  of  the 
thumb  its  whole  length. 

Function. — To  draw  the 
thumb  to  the  fingers. 

The  flexor  brevis  pollicis  (Fig.  232)  arises  by  two  heads, 
the  first  fleshy  from  the  anterior  annular  ligament,  trape- 
zium and  scaphoides,  and  is  inserted  into  the  outer  sesa- 
moid  bone  and  base  of  the  first  phalanx  of  the  thumb. 
The  second  head,  which  is  internal  and  posterior,  arises 
from  the  os  magnum  and  base  of  the  metacarpal  bone 
of  the  middle  finger,  and  is  inserted  into  the  inner  sesa- 
moid  bone  and  base  of  the  first  phalanx  of  the  thumb. 

FIG.  232  represents  the  muscles  of  the  Hand,  a  Annular  ligament,  b  b 
Upper  and  lower  attachments  of  the  abductor  pollicis.  c  Opponens  pollicis. 
d  e  Flexor  brevis  pollicis,  its  two  bellies.  /Adductor  pollicis.  gg  Lumbricales. 
h  Point  where  the  flexor  profundus  tendon  passes  through  the  flexor  perforatus. 
i  Flexor  longus  pollicis.  j  Abductor  minimi  digiti.  k  Flexor  brevis  minimi 
digiti.  /  Os  pisiforme.  m  First  dorsal  interosseous. 


PALMAR  MUSCLES.  T23 

Between  the  two  heads  the  tendon  of  the  flexor  longus 
pollicis  passes. 

Function. — To  bend  the  first  phalanx  of  the  thumb. 

The  adductor  pollicis  (Fig.  232)  arises  fleshy  from  the 
whole  extent  of  the  ulnar  surface  of  the  metacarpal  bone 
of  the  middle  finger.  It  is  a  broad,  triangular  muscle, 
situated  beneath  the  lumbricales  and  tendons  of  the  flexors 
sublimis  and  profundus ;  its  fibres  converge  and  are  in- 
serted tendinous  into  the  inner  base  of  the  first  phalanx  of 
the  thumb.  Function. — To  draw  the  thumb  to  the  fingers. 

The  abductor  indicis  arises,  fleshy  and  tendinous,  from 
the  ulnar  portion  of  the  metacarpal  bone  of  the  thumb, 
its  whole  extent,  and  the  trapezium,  and  is  inserted  along 
the  metacarpal  bone  and  radial  side  of  the  first  phalanx 
of  the  fore  finger.  Function. — To  draw  the  fore  finger  from 
the  rest,  or  adduct  the  thumb. 

MUSCLES   OP   THE  LITTLE   FINGER. 

The  abductor  minimi  digiti  (Fig.  232)  arises  fleshy  from 
the  annular  ligament  and  pisiform  bone,  and  is  inserted, 
after  running  along  the  margin  of  the  metacarpal  bone 
into  the  ulnar  side  of  the  first  phalanx  of  the  little  finger. 

Function. — To  draw  the  little  finger  from  the  others. 

The  adductor  minimi  digiti  arises  fleshy  from  the  annu- 
lar ligament  and  os  unciforme,  and  is  inserted  tendinous 
and  fleshy  into  the  front  of  the  metacarpal  bone  of  the 
fore  finger  its  whole  extent.  Function. — To  flex  and  draw 
the  little  finger  to  the  others. 

The  flexor  brevis  minimi  digiti  (Fig.  232)  arises  fleshy 
from  the  annular  ligament  and  unciform  bone.  It  is  beneath 
the  abductor,  and  is  inserted  tendinous  into  the  base  of  the 
first  phalanx  of  the  little  finger. 

Function. — To  bend  the  little  finger. 

PALMAR  MUSCLES. 

The  palmaris  brevis  arises  from  the  anterior  annular 
ligament  and  palmar  aponeurosis.  It  is  immediately  below 


724  INTEROSSEOUS  MUSCLES. 

the  skin,  covering  the  muscle  of  the  little  finger.  Its  fibres 
are  separated  and  are  inserted  into  the  cellular  tissue  and 
integument. 

Function. — To  contract  the  skin  of  the  palm  and  deepen 
the  hollow  of  the  hand. 

The  lumbricales  (Fig.  232)  are  four  in  number,  and  situ- 
ated below  the  anterior  annular  ligament.  They  each  form 
a  small  fleshy  belly  which  arises  from  the  radial  side  of 
the  tendons  of  the  flexor  profundus,  and  is  inserted  by  a 
flat  tendon  into  the  posterior  part  of  the  first  phalanx  of 
each  finger  along  with  the  tendinous  expansion  of  the 
extensor  communis. 

Function. — To  bend  the  first  phalanges. 

INTEROSSEOUS  MUSCLES,  (Figs.  232,  228.) 

Anterior  interossei. — These  are  three  in  number,  and 
occupy  the  palmar  portion  of  the  hand.  They  arise  fleshy 
and  tendinous  from  the  base  and  sides  of  the  metacarpal 
bone,  and  are  inserted  into  the  base  and  posterior  part  of 
the  first  phalanx  of  the  finger  along  with  the  tendinous 
expansion  of  the  common  extensor.  The  first  palmar  inter- 
osseous  belongs  to  the  fore-finger,  the  second  to  the  ring- 
finger,  and  the  third  to  the  little  finger. 

Function. — Adductors  of  the  fingers. 

Posterior  interossei. — Are  situated  on  the  back  of  the 
hand,  and  fill  the  interosseous  spaces.  They  are  four  in 
number,  and  arise  fleshy,  by  two  heads  from  the  base  and 
sides  of  the  metacarpal  bones,  and  are  inserted  into  the  base 
of  the  first  phalanges  along  with  the  tendinous  expansion 
of  the  common  extensor. 

Function. — Abductors  of  the  fingers. 

SECTION    II. 
FASCIA    OF    THE    SUPERIOR   EXTREMITY. 

The  superior  extremity  is  surrounded  by  an  aponeurotic 
membrane  from  the  shoulder  to  the  hand,  investing  all  its 
muscles  externally,  as  well  as  sending  processes  between 
them,  and  separating  each  from  the  other. 


FASCIA  OF  THE  SUPERIOR  EXTREMITY.  725 

The  shoulder  has  three  divisions  of  this  general  apo- 
neurotic  fascia  ;  one  covering  the  supra-spinatus  muscle 
and  attached  to  the  margins  of  the  supra-spinal  fossa,  called 
the  supra-spinous  fascia ;  a  second,  covering  the  infra-spi- 
natus  and  attached  to  the  margins  of  the  infra  spinal-fossa, 
called  the  infra-spinous  fascia.  Both  of  these  fasciae  are 
strong  and  thick,  and  continued  into  the  third  division — the 
deltoid  fascia.  This  latter  covers  the  deltoid  and  pectoral 
muscles,  is  thin,  and  attached  above  to  the  spine  of  the 
scapula,  acromion  process,  and  external  ends  of  the  clavicle, 
while  below  it  is  traced  into  the  next  fascia  belonging  to 
the  arm,  and  called — 

Fascia  Brachialis. — This  fascia  surrounds  all  the  muscles 
of  the  arm  to  the  elbow,  sends  off  processes  forming  sheaths 
for  the  same,  and  above  the  condyles  of  the  humerus,  these 
processes  separate  the  muscles  on  the  front  of  the  arm  from 
those  behind.  They  are  attached  to  the  ridge  leading  to 
the  condyles,  and  are  called  internal  and  external  intermus- 
cular  ligaments.  At  the  end  of  the  elbow  the  fascia  bra- 
chialis  is  increased  in  strength  by  having  a  broad  band, 
the  bicipital  aponeurosis,  running  into  it.  This  band  comes 
from  the  inner  side  of  the  tendon  of  the  biceps,  which  with 
the  fascia  brachialis,  is  lost  in  the  next  fascia,  called 
the  cubital  fascia.  This  is  the  fascia  of  the  forearm,  ex- 
tending from  the  elbow  to  the  wrists.  It  is  thicker  behind 
than  before ;  surrounds  and  forms  partitions  for  the  several 
muscles,  constituting  at  its  upper  portion  intermuscular 
ligaments,  and  likewise  separating  the  superficial  from  the 
deep  layer  of  muscles,  as  well  as  affording  attachment  for 
many  muscular  fibres.  At  the  wrist  the  cubital  fascia  forms 
two  strong  bands,  the  one  in  front,  the  other  behind,  called 
the  anterior  and  posterior  annular  ligaments. 

The  anterior  is  a  broad  ligamentous  band,  extending 
across  the  wrist  from  the  scaphoides  and  trapezium  on  the 
one  side,  to  the  unciform,  cuneiform  and  pisiform  bones  on 
the  other.  This  band  confines  and  directs  the  flexor  ten- 
dons of  the  fingers  which  pass  beneath  it. 

The  posterior  annular  ligament  stretches  from  the  styloid 


BLOOD-VESSELS  OP  THE  SUPERIOR  EXTREMITY. 

margin  of  the  radius  on  the  one  side,  transversely  to  the 
styloid  margin  of  the  ulna  and  pisiforme  hone  on  the  oppo- 
site side.  This  ligament  presents  six  trochlege  for  the  ex- 
tensor tendons — one  on  the  styloid  side  of  the  radius  for 
the  extensor  ossis  metacarpi  and  extensor  minor  pollicis, 
a  second  for  the  extensor  carpi  radialis  longior  and  brevior, 
a  third  for  the  extensor  major  pollicis,  a  fourth  for  the 
extensor  communis  and  indicator,  a  fifth  for  a  branch  of 
the  extensor  communis,  and  a  sixth  for  the  extensor  carpi 
ulnaris. 

The  aponeurosis  palmaris  belongs  to  the  hand,  and  covers 
its  middle  palmar  portion.  It  is  triangular  in  shape,  and 
extends  from  the  lower  margin  of  the  anterior  annular 
ligament  and  tendon  of  the  palmaris  longus  to  the  lower 
extremities  of  the  metacarpal  hones,  where  it  divides  into 
four  portions,  each  of  which  bifurcates  to  be  attached  to  its 
corresponding  metacarpal  bone,  and  gives  passage  to  the 
vessels  and  nerves  that  go  to  the  fingers.  At  this  point 
the  palmar  fascia  is  strengthened  by  strong  transverse 
fasciculi,  forming  arches,  beneath  which  pass  the  tendons  of 
the  flexor  muscles. 

Vaginal  ligaments  of  the  fingers. — These  are  situated 
along  the  ulnar  and  radial  margins  of  the  phalanges,  and 
are  connected  by  transverse  fibres  so  as  to  form  a  long  tube 
or  sheath,  lined  by  synovial  membrane,  in  which  are  con- 
tained the  flexor  tendons.  These  vaginal  ligaments  are  of 
a  fibro-cartilaginous  character,  and  of  gieat  strength,  and 
within  them  are  observed  little  tendinous  frfena  passing 
from  the  first  and  second  phalanges,  and  connecting  with 
the  tendons  of  the  flexor  profundus  or  sublimis. 

SECTION  III. 

BLOOD  VESSELS   OF   THE  SUPERIOR   EXTREMITY. 

The  subclavian,  axillary,  and  brachial  arteries,  with  their 
branches,  are  the  sources  of  arterial  supply  of  blood  to  the 
shoulder,  arm,  forearm,  and  hand,  comprising  the  upper 
extremity.  Those  coming  from  the  subclavian  have  been 


ARTERIES  OF  THE  SHOULDER. 


FIG.  233. 


described  under  the  head  of  blood-vessels  of  the  neck.   (See 
Figs.  120,  153.) 

ARTERIES   OP   THE  SHOULDER. 

Axillary  artery,  (axilla,  the  arm-pit.)  —  The  axillary 
artery  is  the  continued  trunk  of  the  subclavian,  and 
receives  this  name  at  the 
lower  border  of  the  first 
rib,  behind  the  subclavian 
muscle  and  clavicle ;  from 
this  point  it  descends  ob- 
liquely outward  through 
the  axillary  space,  where 
it  is  surrounded  by  a  quan- 
tity of  loose  cellular  and 
adipose  tissue,  containing 
many  lymphatic  glands, 
and  terminates  at  the 
lower  edge  of  the  tendi- 
nous insertions  of  the  la- 
tissimus  dorsi  and  teres 
major  muscles  in  the  bra- 
chial  artery. 

In  its  course  it  is  seen  to  pass  behind  the  pectoralis  major 
and  minor,  resting  upon  the  first  intercostal  and  serratus 
magnus,  and  having  the  coraco-brachialis  on  its  outer  or 
humeral  side.  The  axillary  vein  ascends  in  front  and  to 
the  inside.  Above  the  little  pectoral  muscle,  the  brachial 
plexus  of  nerves  is  to  the  outside  of  this  artery,  behind  the 
muscle,  and  surrounds  it  in  such  manner  that  it  is  embraced 
by  the  outer  and  inner  roots  of  the  median  nerve,  and  a 
little  lower  down  it  has  the  median  nerve  in  front,  the 
radial  behind,  the  ulnar  and  internal  cutaneous  on  the 

FIG.  233  represents  the  axillary  artery  and  nerves,  a  Deltoid.  6  Clavicle, 
c  Subclavius.  d  Pectoralis  minor,  e  Second  rib.  /Axillary  vein,  g  Axillary 
artery,  h  Space  between  brachial  artery  and  brachial  plexus  of  nerves. 
(Superior  thoracic  artery.  jThoracia  media.  fcThoracica  acromialis,  its 
descending  branch.  Jits  acromial  branch.  mThoracica  inferior  artery  and 
nerve,  n  Thorcica  alaris.  o  Internal  cutaneous  and  ulnar  nerves,  p  Median 
nerve,  q  External  cutaneous  nerves,  r  Coraco  brachialis.  s  Biceps. 


j^        ARTERIES  OP  THE  SHOULDER. 

inside,   and    the    external   or   musculo-cutaneous   on  the 
outside. 

BRANCHES   OF   THE   AXILLARY   ARTERY,  (Fig.    233.) 

The  thoracica-acromialis ,  or  acromial  thoracic  artery, 
ascends  above  the  pectoralis  minor,  and  sends  "branches, 
called  thoracic,  to  the  pectoral  and  serratus  magnus  muscles, 
branches  to  the  acromion,  and  a  descending  branch  be- 
tween the  deltoid  and  great  pectoral.  It  anastomoses  with 
the  supra  scapular. 

The  superior  or  short  thoracic  often  has  a  common  origin 
with  the  thoracica-acromialis.  It  passes  along  the  upper 
border  of  the  little  pectoral  muscle,  and  supplies  the  pec- 
toral muscles  and  mammary  gland,  anastomosing  with  the 
intercostal  and  mammary  arteries. 

The  inferior  or  long  thoracic,  called  also  the  external 
mammary,  differs  from  the  two  last  by  arising  below  the 
lesser  pectoral  muscle.  Sometimes  it  is  a  branch  of  the 
subscapular  or  acromial  artery,  or  has  a  common  trunk 
with  them.  It  goes  along  the  inferior  edge  of  the  great 
pectoral  muscle,  supplying  it,  the  mammary  gland,  the 
great  serratus  muscle  and  the  integuments,  and  anasto- 
mosing with  the  superior  thoracic,  the  intercostal  and  the 
mammary  arteries. 

The  thoracica-axillaris ,  frequently  a  branch  of  the  tho- 
racic, is  distributed  to  the  glands  of  the  axilla. 

The  subscapular  artery,  (scapularis  inferior,,)  the  largest 
branch  of  the  axillary,  descends  along  the  lower  edge  of 
the  subscapularis  muscle  to  the  inferior  angle  of  the  scapula- 
In  its  course  it  sends  branches  to  the  axilla,  and  about  an 
inch  from  its  origin  it  gives  off  the  dorsalis  scapulw,  sup- 
plies the  subscapularis,  serratus  magnus,  and  latissimus 
dorsi  muscles,  tfyen  winds  around  the  inferior  costa  of  the 
scapula  to  its  dorsum,  anastomosing  with  the  superior 
scapular,  and  terminating  upon  the  infra-spinatus  muscle, 
where  it  is  called  dorsalis  inferior  scapula*. 

The  anterior  circumflex  artery  arises  above  the  tendon  of 
the  teres  major  from  the  axillary.  Sometimes  it  is  a  branch 


ARTERIES   OF   THE   ARM.  *729 

of  the  posterior  circumflex,  and  passes  outward  in  front  of 
the  humerus,  beneath  the  biceps,  coraco-brachialis  and 
deltoid,  supplying  these  muscles,  and  sending  a  branch 
along  the  bicipital  groove  to  the  shoulder  joint. 

The  posterior  circumflex  artery  arises  below  the  last,  and 
is  a  larger  branch.  It  goes  round  the  neck  of  the  humerus, 
between  the  latter  and  the  long  head  of  the  triceps,  to 
supply  the  shoulder  joint  and  deltoid  muscle.  Sometimes 
it  is  a  branch  of  the  superior  profunda. 

ARTERIES  OF  THE  ARM. 

BRACHIAL  ARTERY,    (Fig.    234.) 

The  brachial  artery  is  the  continued  trunk  of  the  axillary, 
and  extends  from  the  lower  margin  of  the  tendinous  inser- 
tions of  the  latissimus  dorsi  and  teres  major  muscles,  to  a 
little  below  the  bend  of  the  elbow  joint,  where  it  divides 
into  the  radial  and  ulnar  arteries. 

Its  course  is  along  the  inner  edge  of  the  coraco-brachialis 
and  biceps  muscles,  resting  upon  the  coraco-brachialis  and 
brachialis  anticus.  It  has  the  basilic  vein  in  front,  and 
the  venae  comites  on  either  side.  The  median  nerve  is  also 
in  front,  though  at  the  upper  part  it  lies  to  the  outside  of 
the  artery,  and  below  to  the  inner  side.  It  is  covered  by 
the  fascia  of  the  arm,  and  at  the  bend  of  the  elbow  by  the 
bicipital  aponeurosis  and  median  basilic  vein. 

BRANCHES  OF  THE  BRACHIAL  ARTERY. 

The  profunda  superior  or  spiralis  comes  from  the  brachial 
just  below  the  teres-major,  winds  round  the  back  part  of 
the  humerus  along  with  the  musculo-spiral  nerve,  between 
the  second  and  third  heads  of  the  triceps,  to  the  external 
condyle,  where  it  anastomoses  with  the  radial  recurrent, 
and  sends  a  descending  branch  along  the  triceps  to  the 
olecranon. 

The  nutritious  artery  comes  from  the  brachial  about  the 
middle  of  the  arm,  and  enters  the  medullary  foramen  of 
the  humerus  to  supply  its  lining  membrane. 


730 


ARTERIES  OF  THE  ARM. 


The  profunda  inferior  or  minor  arises  opposite  the  tendon 


FIG.  234. 


of  the  coraco-brachialis 
below  the  superior  pro- 
funda, and  passes  inward 
and  downward  to  the  in- 
ner condyle  along  with 
the  ulnar  nerve,  and  an- 
astomoses with  the  ulnar 
recurrent.  It  is  some- 
times a  branch  of  the  su- 
perior profunda. 

The  anastomotica  magna 
comes  off  from  the  bra- 
chial  about  two  inches 
above  the  joint,  rests  upon 
the  brachialis  anticus,  and 
passing  inward  above  the 
inner  condyle,  supplies 
the  adjacent  muscles,  and 
anastomoses  with  the  ul- 
nar recurrent  and  inferior 
profunda. 

Muscular  branches  are 
sent  off  in  the  course  of 
the  artery  to  the  various 
muscles. 

Varieties    in    the    bra- 

FIG.  234  represents  the  Brachial  Artery  and  Nerves.  1  Subscapularis  mus- 
cle. 2  Teres  major.  3  Dorsalis  scapulae  branch  of  the  subscapular  artery. 
4  Clavicle.  5  Coracoid  process.  6  Deltoid.  7  Insertion  of  pectoralis  major. 
8  Coraco  brachialis.  9  Biceps.  11  Long  head  of  triceps.  12  Its  short  head. 
13  Axillary  artery.  14  Brachial  artery.  15  Bicipital  aponeurosis.  16  Long 
thoracic  artery.  17  Inferior  profunda.  18  Anastomotica  magria.  19  Ante- 
rior and  posterior  ulnar  veins.  20  Median  vein.  22  Median  cephalic.  23 
Radial  vein.  24  Median  basilic.  26  Basilic  vein.  27  Subscapular  artery. 
28  External  or  musculo-cutaneous  nerve.  29  Thoracica  acromialis  artery. 
30  Brachial  plexus.  31  Cephalic  vein.  32  Median  nerve.  33  Ulnar  nerve. 
34  Musculo-spiral  or  radial  nerve.  35  Circumflex  nerve.  36  Internal  cuta- 
neous nerve.  37  Intercosto  humeral  nerve.  38  Superior  profunda  artery. 
39  Anterior  branch  of  internal  cutaneous  nerve.  40  Branches  of  external  cu- 
taneous nerve. 


ARTERIES   OF   THE  FOREARM. 

chial  artery  are  chiefly  noticed  in  the  high  division  of  its 
radial  and  ulnar  branches,  which  may  occur  at  any  point 
between  the  elbow  and  the  axilla. 

ARTERIES    OF    THE    FOREARM. 
RADIAL   ARTERY,    (Fig.  235.) 

The  radial  artery  seems  to  be  the  continued  trunk  of  the 
brachial,  and  extends  from  the  bend  of  the  elbow  to  the 
wrist.  At  its  upper  part,  it  is  between  the  supinator  radii 
longus  and  pronator  radii  teres.  It  descends  along  the  ra- 
dial side  of  the  forearm,  covered  only  by  the  skin  and 
fascia,  crosses  over  the  tendon  of  the  biceps  and  pronator 
teres ;  and  at  its  lower  part  lies  between  the  supinator 
longus  and  flexor  carpi  radialis.  Here  it  passes  outward 
on  the  back  of  the  wrist  behind  the  extensor  tendons  of 
the  thumb,  and  dips  down  into  the  palm  of  the  hand,  be- 
tween the  roots  of  the  metacarpal  bones  of  the  thumb  and 
fore  finger,  where  it  terminates  in  the  arcus  profundus,  or 
deep  palmar  arch.  The  radial  artery  in  its  course  is  ac- 
companied by  venae  comites,  and  by  the  radial  nerve  as  far 
as  the  middle  of  the  forearm. 

BRANCHES  OF  THE  RADIAL  ARTERY. 

The  recurrens  radialis  arises  opposite  the  neck  of  the 
radius,  passes  upward  and  outward  to  the  external  condyle, 
and  anastomoses  with  the  profunda  superior. 

Muscular  branches  are  sent  off  in  its  course  to  the  various 
muscles,  supinators,  and  flexors. 

The  superficial  is  voice  comes  off  as  the  artery  is  curving 
upon  the  wrist,  and  supplies  the  ball  of  the  thumb. 

The  dorsalis  carpi  arises  next  in  order  and  supplies  the 
interosseous  muscles  of  the  back  of  the  hand. 

The  radialis  indicis  comes  off  at  the  root  of  the  metacar- 
pal bone  of  the  thumb,  and  goes  along  the  radial  side  of 
the  fore  finger  to  its  extremity. 

The  magna  pollicis  arises  at  the  same  point  with  the  last, 
and  at  the  head  of  the  metacarpal  bone  of  the  thumb 
divides  into  two  branches,  which  supply  each  side  of  the 
thumb  to  its  extremity. 


732 


ARTERIES  OF  THE  FOREARM. 


THE  ULNAR  ARTERY,  (Fig.  235.) 

The  ulnar  artery  is  larger  than  the  radial,  and  forms 
FIG.  235.  the  remaining  terminal  branch  of  the 

brachial ;  it  extends  from,  the  bend 
of  the  elbow  to  the  wrist,  where  it 
terminates  in  the  arcus  sublimis,  or 
superficial  palmar  arch.  At  its  up- 
per end  it  crosses  the  arm  obliquely, 
covered  by  the  pronator  teres,  flexor 
sublimis,  flexor  radialis,  and  palma- 
ris  longus,  to  the  middle  of  the  fore- 
arm, where  it  is  traced  along  the 
radial  margin  of  the  flexor  carpi  ulna- 
ris to  the  wrist.  Here  it  passes  over 
the  anterior  annular  ligament  into 
the  palm.  It  is  attended  by  vena3 
comites,  and  the  uluar  nerve. 

BRANCHES   OF   THE  ULNAR  ARTERY. 

The  recurrens  ulnaris  anterior  comes 
from  the  ulnar  artery  about  the  tu- 
bercle of  the  radius,  and  ascends  in 
front  of  the  inner  condyle. 

The  recurrens  ulnaris  posterior  as- 
cends behind  the  inner  condyle,  and 
with  the  anterior,  anastomoses  with 
the  anastomotica  and  inferior  pro- 
funda. 

FIG.  235  represents  the  Radial  and  Ulnar  Arteries.  1  Biceps.  2  Its  tendon. 
3  Triceps.  4  Anastom.otica  magna  artery.  5  Brachialis  anticus.  6  Radial 
or  musculo-spiral  nerve.  7  Supinator  longus.  8  Internal  condyle.  9 
Flexor  carpi  ulnaris.  11  Interosseous  artery.  12  Median  nerve.  13  Flexor 
sublimis  digitorum.  14  Annular  ligament  divided.  15  Superficial  palmar  arch- 
16  Superficial  is  volae.  17  Branch  of  ulnar  nerve.  18  Radialis  indicis  artery. 
19  Anterior  ulnar  recurrent  artery.  20  Tendon  of  supinator  longus.  21  Inferior 
profunda  artery.  22  Ulnar  nerve.  23  Brachial  artery.  24  Median  nerve. 
25  Recurrent  radial  artery.  26  Radial  nerve  27  Radial  artery.  28  Prona- 
tor radii  teres.  29  Flexor  carpi  radialis.  30  Palmaris  longus— these  three 
latter  muscles  are  cut  across.  31  Ulnar  nerve.  32  Ulnar  artery.  33  Branch 
of  the  radial  nerve. 


ARTERIES  OF  THE  HAND.  733 

The  interosseous  artery  arises  just  below  the  last,  and 
divides  after  a  short  course  into  two  branches,  an  anterior 
and  a,  posterior. 

The  anterior  interosseous  artery  descends  in  front  of  the 
interosseous  ligament  behind  the  deep  flexors  to  the  prona- 
tor  quadratus,  where  it  penetrates  this  ligament  to  the 
back  of  the  wrist,  and  anastomoses  with  the  radial  and 
posterior  interosseous. 

The  posterior  interosseous  artery  is  the  smaller  branch, 
and  sometimes  arises  as  a  separate  trunk ;  it  soon  passes 
through  the  interosseous  ligament  to  the  back  of  the  arm, 
and  then  descends  to  supply  the  extensor  muscles.  At  its 
upper  end  it  gives  off  a  recurrent  branch  to  the  posterior 
part  of  the  elbow,  which  anastomoses  with  the  recurrens 
radialis  and  ulnaris. 

Muscular  branches,  numerous  and  irregular,  are  given  off 
in  its  course. 

The  dorsalis  carpi  ulnaris  comes  off  at  the  lower  end  of 
the  ulna,  and  winds  beneath  the  flexor  ulnaris  tendon  to 
the  back  of  the  wrist,  where  it  anastomoses  with  the  radial 
and  interosseal,  to  supply  the  carpus,  metacarpus,  and 
phalanges. 

Varieties. — The  ulnar  artery  may  arise  from  the  axillary, 
the  interosseal  from  the  radial,  brachial,  or  axillary.  In- 
deed it  is  difficult  to  say  what  will  be  the  distribution  of 
the  arteries  of  the  forearm  until  it  is  examined. 

ARTERIES   OF   THE    HAND,  (Fig.  236.) 

The  arcus  sublimis  or  superjicicdis  is  the  continued  trunk 
of  the  ulnar  artery,  and  extends  from  the  lower  border  of 
the  annular  ligament  across  the  palm  of  the  hand  to  the 
thumb,  to  anastomose  with  the  radial ;  after  supplying 
the  muscles  of  the  palm,  it  sends  deeply  a  larger  branch, 
called  cubitalis  manus  profunda,  to  unite  with  the  arcus 
profundus. 

It  next  sends  off  the  digital  arteries.  These  are  four  in 
number ;  the  first  goes  on  the  ulnar  side  of  the  little  finger ; 
the  others  proceed  to  the  heads  of  the  metacarpal  bones, 


•734 


ARTERIES  OF  THE  HAND. 


where  they  each  divide  and  run  alorig  the  adjacent  sides  of 
opposing  fingers  to  their  extremities,  excepting  the  radial 
side  of  the  index  finger  which  is  supplied  from  the  radial. 

The  circus  profundus 
is  one  of  the  termina- 
ting branches  of  the 
radial ;  it  extends  from 
the  root  of  the  me- 
tacarpal  bone  of  the 
thumb,  deep  into  the 
palm  of  the  hand,  be- 
hind the  flexor  ten- 
dons, and  close  to  the 
metacarpal  bones, 
forming  an  arch  across 
the  hand  from  the  ra- 
dial to  the  ulnar  side, 
to  anastomose  with 
the  superficial  arc.  In 
its  course  it  gives  off 
branches  to  the  inter- 
osseous  muscles,  and 
perforating  branches 
through  the  interos- 
seous  spaces  to  the  dorsal  interossei.  The  arteries  of  the 
hand  are  subject  to  great  variety. 

FIG.  236,  A  represents  the  arcus  superficialis.  a  Ulnar  artery.  6  Its  rela- 
tion with  the  annular  ligament,  c  Ulnar  artery  in  the  palm  of  the  hand. 
d  e  fg  h  i  Its  digital  branches,  j  Place  of  anastomosis  with  the  arcus  profundus. 
k  Point  where  the  radial  artery  terminates.  I  I  Digito  radial  arteries- 
m  m  Digito  ulnar  arteries,  nn  Place  where  the  radial  and  ulnar  digital 
branches  anastomose,  o  Radial  artery,  p  Its  place  of  turning  on  the  back  of 
the  hand,  q  Its  last  branch,  called  radialis  indicis.  r  Termination  of  arcus 
profundus.  s  t  Muscular  branches  of  the  radial  at  the  wrist,  u  v  Superficialis 
volae. 

FIG.  236,  B  represents  the  arcus  profundus.  c  Point  where  the  radial  artery 
enters  the  palm  of  the  hand.  &  Anastomosing  branch,  c  Branch  on  the  side 
of  the  thumb.  (/Branch  to  Ihe  fore  finger,  e  Anastomosis  of  arcus  profundus 
with  an  ulnar  digital  branch.  /  Arteria  magna  pollicis.  g  h  ij  k  I  Interosseous 
branches. 


VEINS   OF   THE  SUPERIOR   EXTREMITY. 


735 


Fio.  237. 


VEINS  OF  THE  SUPERIOR  EXTREMITY. 

The   veins   of   the    superior    extremity   begin    at    the 
extremity   of  the   fingers,    and    are 
divided   into   the   superficial  and 
deep. 

The   superficial   are   the   cephalic, 
basilic,  and  median  veins. 

The  cephalic  is  formed  on  the  back 
of  the  wrist  by  the  union  of  the  dor- 
sal veins  of  the  hand.  It  ascends 
along  the  radial  side  of  the  fore- 
arm to  the  elbow,  and  thence  up- 
ward along  the  outer  side  of  the 
biceps  to  the  groove  between  the 
pectoral  and  deltoid  muscles,  where 
it  dips  down  to  join  the  axillary 
vein  just  below  the  clavicle. 

The  basilic  begins  at  the  lower 
extremity  of  the  ulna  by  several 
branches,  one  of  which  from  the 
little  finger  is  called  vena  salvatella. 
It  ascends  along  the  ulnar  side  of 
the  forearm  to  the  inner  condyle, 
thence  to  the  inner  side  of  the  arm, 
where  it  penetrates  the  fascia,  gets 
in  front  of  the  brachial  artery,  and 
joins  the  brachial  vein.  The  basilic 
often  ascends  the  forearm  by  two 
trunks,  an  anterior  and  posterior, 
which  unite  into  one  just  below  the 
elbow-joint. 

FIG.  237  represents  the  veins  of  the  Superior  Extremity,  a  Axillary  artery, 
b  Axillary  vein,  c  Brachial  vein,  dd  Basilic  vein,  a  portion  under  and  a  portion 
without  the  brachial  fascia,  e  Union  of  median  basilic  with  the  basilic. 
/Posterior  basilic,  g  Anterior  basilic.  (Termination  of  cephalic  vein  in  the 
axillary,  j  Cephalic  beneath  the  fascia,  k  Union  of  median  cephalic  with  the 
cephilic  vein.  /Cephalic  vein,  its  inferior  portion,  m  Median  cephalic, 
n  Median  vein,  o  Anastomosis  of  superficial  and  deep  veins,  p  Branches  of 
cephalic  vein  to  the  thumb,  q  Digital  vein,  r  Palmar  veins. 


736  NERVES  OF  THE  SUPERIOR  EXTREMITY. 

The  median  vein  begins  by  branches  from  the  palm  of 
the  hand  and  wrist,  ascends  along  the  middle  of  the  fore- 
arm to  the  elbow,  where  it  divides.  One  branch,  the  median 
cephalic,  joins  the  cephalic  vein ;  the  other,  the  median 
basilic.,  joins  the  basilic  vein.  (See  Fig.  23*7.) 

The  superficial  veins  all  lie  immediately  beneath  the 
skin  and  upon  the  fascia. 

The  deep  veins  correspond  to  the  several  arteries,  and 
have  the  same  names  as  the  arteries  they  accompany,  each 
artery  having,  however,  two  veins,  called  vence  comites. 
Hence  we  have  radial,  ulnar  and  interosseal  veins,  all 
ascending  beneath  the  fascia  to  the  bend  of  the  arm,  where 
they  unite  into  the  brachial  vein,  which  is  often  double, 
composed  of  two  vense  comites  accompanying  the  brachial 
artery,  and  receiving  in  their  course  the  profunda  and 
anastomotic  veins.  The  brachial  vein  at  the  lower  margin 
of  the  tendon  of  the  teres  major  becomes  the  axillary  vein, 
which  goes  in  front  of  the  axillary  artery,  and  receives  in 
its  course  the  thoracic  and  circumflex  veins,  and  finally 
ends  in  the  subclavian,  already  described  among  the  ves- 
sels of  the  neck. 

SECTION   IV. 
NERVES   OF  THE  SUPERIOR  EXTREMITY. 

The  brachial  or  axillary  plexus  (Fig.  233)  is  the  source  of 
nervous  supply  to  the  upper  extremity.  This  plexus  is 
formed  by  the  junction  of  the  anterior  branches  of  the  four 
inferior  cervical,  and  first  dorsal  nerves.  It  extends  from 
the  scaleni  muscles  to  the  neck  of  the  humerus,  in  the 
axilla,  where  they  so  interlace  as  to  surround  the  axillary 
artery. 

For  further  account  of  the  brachial  plexus,  see  Nerves  of 
the  Neck. 

BRANCHES   OF  THE  AXILLARY  PLEXUS. 

Thoracic,  Internal  cutaneous,  Median, 

Supra-scapular,         External  cutaneous,  Ulnar, 

Sub-scapular,  Circumflex,  Kadial. 


NERVES  OF  THE  SHOULDER. 


737 


These  nerves  vary  considerably  as  to  their  number  and 
origin,  in  the  axillary  plexus ;  FlG-  238. 

hence  the  diversity  of  the  state- 
ments of  different  anatomists 
in  their  descriptions  of  them. 

The  thoracic  nerves  come 
from  the  plexus,  about  its 
middle,  and  vary  in  number 
from  two  to  five.  They  are 
divided  into  anterior  and  pos- 
+terior  branches;  the  former 
supply  the  subclavian  and  pec- 
toral muscles,  and  the  latter 
go  to  the  serratus  magnus, 
posterior  scalenus,  and  rhom- 
boid muscles. 

The  supra-scapular  comes 
from  the  upper  portion  of  the 
plexus,  and  accompanies  the 
superior  scapular  artery  to 
the  notch  or  foramen  in  the 
-superior  costa  of  the  scapula, 
through  which  it  passes  to 
supply  the  supra-spinatus.  It 
also  passes  behind  the  neck  of 
the  scapula  to  be  distributed 
upon  the  infra-spinatus  and 
teres  minor  muscles. 

The  sulscapular  nerves   are 
three  or  four  in  number ;  they 
vary  in   their  origin,  but  mostly  arise  either  from   the 
upper  or  central  portions  of  the  plexus.     They  are  distrib- 

FIG.  238  represents  the  nerves  of  the  Superior  Extremity.  A  Axillary  ar- 
tery. B  Brachial  artery,  b  Supra-scapular  nerve,  c  Subscapular.  d  Inter 
nal  cutaneous,  e  Musculo  or  external  cutaneous  nerve.  /  Circumflex,  g 
Ulnar  nerve,  h  Superficial  branch  of  the  latter  on  the  hand.  I  Median  nerve, 
m  Anterior  interosseous  nerve,  o  Musculo-spiral  nerve,  p  Radial,  q  Posterior 
interosseous  nerve. 

47 


738 


SERVES  OF  THE  ARM. 


nted  to  the  subscapular,  latissimus  dorsi,  and  teres  major 

muscles. 

The  internal  cutaneous  nerve  (Fig.  239)  arises  from  the 

lower  part   of  t  the   plexus,    in  common   with   the   inner 

head  of  the  median,  and  is  among   the  smallest  of  the 
FIG.  239.  nerves   supplying   the   arm.      It   de- 

scends in  company  with  the  basilic 
vein,  and  above  but  near  the  elbow  it 
divides  into  an  external  or  anterior, 
and  internal  or  posterior  branch.  Be- 
fore this  division,  the  nerve  sends 
filaments  through  the  fascia  to  the 
biceps,  the  inner  portion  of  the  tri- 
ceps,  and  the  integuments.  The  exter- 
nal branch  goes  in  front,  and  some- 
times behind,  the  median  basilic  vein. 
Sometimes  there  is  a  branch  of  it  both 
in  front  and  behind  the  vein ;  it  de- 
scends over  the  bend  of  the  elbow  to 
fie  forearm,  as  low  as  the  wrist,  sup- 
plying the  Integuments  in  its  course. 
The  internal  branch  goes  to  the  inner 
condyle,  and  separates  into  filaments, 
some  of  which  go  in  front,  but  the 

most  pass  on  the  back  part  of  the  forearm,  to  supply  chiefly 

the  integuments. 

The  lesser  internal  cutaneous,  or  nerve  of  Wrisberg,  (Fig. 

239,)  comes  also  from  the  lower  part  of  the  plexus,  and  is 

considered  an  accessory  branch  to  the  internal  cutaneous. 

It  is  a  small,  long  branch,  passing  down  the  back  of  the 

arm,  and  at  the  middle  of  the  latter  going  through  the 

FIG.  239  represents  the  Cutaneous  Nerves  of  the  Elbow  Joint,  a  Radial 
vein.  6  Cephalic  vein,  c  Anterior  ulnar  vein,  d  Posterior  ulnar  vein,  t 
Common  ulnar  vein.  /  Basilic  vein,  g  Where  basilic  vein  pierces  the  fascia. 
h  Median  vein,  i  A  deep  vein  uniting  with  the  median,  j  Median  cephalic. 
k  Median  basilic.  J  Fascia,  m  Aponeurotic  band  from  the  tendon  of  the 
biceps,  n  Cutaneous  portion  of  musculo-cutaneous  nerve,  o  Internal  cutane- 
ous nerve,  p  Lesser  internal  cutaneous,  or  nerve  of  Wrisberg.  q  External 
cutaneous  branch  of  musculo-spiral  nerve. 


NERVES  OF  THE  ARM. 

fascia,  to  be  distributed  to  the  integuments  about  the 
elbow.  It  communicates  with  filaments  of  the  internal 
cutaneous  and  musculo-spiral  nerves,  and  in  the  axilla 
with  the  first  intercosto-humeral  nerve^ 

The  external  cutaneous,  (Fig.  239,)  called  also  musculo- 
cutaneous,  or  perforans  Casserii,  comes  from  either  the 
upper  or  middle  division  of  the  plexus,  is  larger  than  the 
last,  and  descends  by  perforating  the  coraco-brachialis 
muscle.  It  then  passes  outward  between  the  biceps  and 
brachialis  anticus,  distributing  filaments  to  these  muscles, 
and  at  the  bend  of  the  elbow  it  becomes  superficial,  joins 
the  cephalic  vein,  and  descends  to  the  wrist,  where  it 
divides  into  branches,  some  of  which  are  anterior,  supply- 
ing the  ball  of  the  thumb,  others  posterior,  distributed  to 
the  back  of  the  hand. 

The  circumflex  or  articular  nerve  arises  from  the  lower 
part  of  the  plexus,  and  passes  along  with  the  posterior 
circumflex  artery,  around  the  neck  of  the  humerus,  between 
the  teres  minor  and  major  muscles,  to  be  distributed  on 
the  inner  surface  of  the  deltoid.  This  nerve  encircles  the 
neck  of  the  humerus  by  a  superior  and  inferior  branch. 

The  median  or  brachial  nerve,  (Fig.  235;)  so  called  from 
being  between  the  ulnar  and  radial  nerves,  arises  by  two 
roots  and  descends  the  arm  in  front  of  the  brachial  artery, 
inclining  however  above  rather  to  the  outer  side  of  the 
artery,  and  below  to  its  inner  or  ulnar  side.  It  goes  along 
the  inner  edge  of  the  biceps  muscle,  and  at  the  bend  of  the 
elbow  is  seen  on  the  ulnar  side  of  the  supinator  longus 
beneath  the  bicipital  aponeurosis.  Here  it  perforates  the 
pronator  teres,  and  descends  the  middle  of  the  forearm, 
between  the  superficial  and  deep  flexors,  to  the  anterior 
annular  ligament  of  the  wrist,  beneath  which  it  passes  to 
the  palm  of  the  hand,  there  to  terminate  in  digital  branches. 

The  median  nerve  gives  off  at  the  bend  of  the  elbow 
muscular  branches,  supplying  most  of  the  flexors  and  pro- 
nators;  next,  the  interosseous  nerve,  a  considerable  branch 
which  accompanies  the  anterior  interosseal  artery,  sup- 
plying the  deep  flexors  in  its  course.  At  the  pronator 


740  NERVES  OF  THE  ARM. 

quadratus,  after  supplying  it,  it  goes  through  the  inter- 
osseous  ligament  to  the  back  of  the  hand.  At  the  wrist 
the  median  sends  a  branch  over  the  annular  ligament  to 
the  integuments  on  the  ball  of  the  thumb  and  palm  of  the 
hand,  called  the  superficial  palmar. 

In  the  palm,  as  stated,  the  median  divides  into  digital 
branches,  which  are  five  in  number.  The  first  two  go  along 
on  either  side  of  the  thumb,  the  third  along  the  radial  side 
of  the  fore  finger,  the  fourth  divides  and  runs  along  the 
adjacent  sides  of  the  fore  and  middle  fingers,  and  the  fifth 
also  divides  to  supply  the  adjacent  sides  of  the  middle  and 
ring  fingers.  A  muscular  branch  is  also  seen  going  from 
the  median  to  the  muscles  of  the  ball  of  the  thumb.  These 
digital  nerves  all  accompany  the  digital  arteries. 

The  ulnar  nerve  (Fig.  235)  comes  from  the  lower  part  of 
the  plexus  and  descends  along  the  anterior  and  internal 
part  of  the  triceps  to  the  inner  condyle,  between  which 
and  the  olecranon  it  passes.  It  also  goes  between  the  two 
heads  of  the  flexor  carpi  ulnaris,  and  gets  to  the  front  of 
the  forearm,  along  the  ulnar  edge  of  which  it  descends  to 
the  wrist ;  here  it  passes  over  the  annular  ligament,  adja- 
cent to  the  pisiforme  bone,  and  in  the  palm  of  the  hand 
divides  into  a  superficial  and  deep  branch. 

To  the  various  muscles  along  its  course  muscular  branches 
are  given  off.  A  little  above  the  wrist  it  sends  off  the 
dorsalis  carpi,  which  gets  to  the  back  of  the  wrist  beneath 
the  tendon  of  the  flexor  ulnaris,  to  supply  the  integuments 
on  the  back  of  the  hand  and  the  two  last  fingers.  The 
superficial  terminating  branch  of  the  ulnar  divides  so  as  to 
supply  both  sides  of  the  little  finger  and  the  ulnar  side  of 
the  ring  finger.  There  is  also  a  branch  communicating 
with  the  median.  The  deep  branch  dips  beneath  the  flexor 
tendons  to  form  the  deep  palmar  arch  and  to  supply  the 
interossei  muscles. 

The  radial  or  musculo-spiral  nerve  (Fig.  235)  comes  from 
different  parts  of  the  axillary  plexus.  It  is  a  large  nerve, 
and  descends  obliquely  outward  round  the  humerus  along 
with  the  superior  profunda  artery,  between  the  triceps 


NERVES   OF  THE  ARM. 

muscle  and  the  bone,  to  the  outer  side  of  the  humerus, 
between  the  triceps  and  the  brachialis  anticus  muscles. 
At  the  bend  of  the  elbow  it  divides  into  an  anterior  and 
posterior  branch. 

The  anterior,  called  ramus  superficial  anterior,  appears 
to  be  the  continued  trunk  of  the  radial,  accompanies  the 
radial  artery  to  a  little  below  the  middle  of  the  radius,  and 
then  goes  beneath  the  tendon  of  the  supinator  longus  to 
the  back  of  the  hand,  where  it  becomes  cutaneous  and 
divides  into  two  branches,  the  one  supplying  the  back  of 
the  hand,  the  thumb,  the  fore  and  middle  fingers;  the  other 
going  to  the  muscles  and  integuments  of  the  thumb. 

The  posterior  branch  of  the  radial,  called  also  posterior 
interosseal,  or  ramus  profundus  dorsalis,  gets  to  the  back  of 
the  forearm,  accompanies  the  posterior  interosseal  artery, 
and  supplies  the  extensor  muscles. 

Above  the  external  condyle,  a  short  distance,  a  branch 
called  ramus  superficialis  dorsalis  is  given  off.  After  send- 
ing filaments  to  the  supinators  and  extensors  at  the  outer 
condyle,  it  becomes  cutaneous,  and  descends  the  forearm 
along  the  radial  margin  of  the  supinator  longus  to  the 
back  of  the  hand. 

The  intercosto-humeral  nerves  (Fig.  234)  are  described  as 
two  branches,  one  coming  from  the  second,  the  other  from 
the  third  thoracic.  The  first  is  seen  beneath  the  second, 
the  other  beneath  the  third  rib.  The  first  is  connected  with 
the  lesser  internal  cutaneou^,  and  supplies  the  axilla,  its 
skin  and  glands;  the  other  descends  as  low  as  the  elbow, 
chiefly  supplying  the  integuments  on  the  back  of  the  arm. 

SUMMARY  OF  THE  MUSCLES  OF  THE  SUPERIOR  EXTREMITY. 

MUSCLES  OF    THE    SHOULDER. 
Deltoid.  Teres-minor. 

Supra-spinatus.  Teres-major. 

Infra-spinatus.  Subscapularis. 

MUSCLES    OF    THE    ARM. 
ON    THE    FRONT.  ON    THE    BACK. 


Biceps  flexor  cubiti. 
Coraco-brachialis. 
Brachialis  anticus. 


Triceps  extensor  cubiti. 
Anconeus. 


742 


OS  FEMORIS. 


MUSCLES     OF    THE    FOREARM. 


ON   THE    FRONT. 

Pronator  radii  teres. 

Flexor  carpi  radialis. 

Palmaris  longus. 

Flexor  carpi  ulnaris. 

Flexor  sublimis  digitorum  perforatus. 

Flexor  profundus  perforans. 

Flexor  pollicis  longus. 

Pronator  quadratus. 


ON   THE    BACK. 

Supinator  radii  longus. 
Extensor  carpi  radialis  longior. 
Extensor  carpi  radialis  brevier. 
Extensor  carpi  ulnaris. 
Extensor  communis  digitorum. 
Extensor  ossis  metacarpi  pollicis. 
Extensor  minor  pollicis. 
Extensor  major  pollicis. 
Indicator. 
Supinator  radii  brevis. 


Palmaris  brevis. 
Abductor  pollicis  manus. 
Opponens  pollicis. 
Flexor  brevis  pollicis. 
Adductor  pollicis. 


MUSCLES    OF    THE    HAND. 

Abductor  minimi  digiti. 
Flexor  brevis  minimi  digiti. 
Adductor  minimi  digiti. 
Lumbricales. 
Interossei. 


INFERIOR    EXTREMITY. 

THE  INFERIOR  EXTREMITY  COMPRISES  BONES,  LIGAMENTS,  MUSCLES, 
FASCIA,    BLOOD-VESSELS,    AND    NERVES,    AND    WILL    BE    EXAM- 
INED   UNDER    THESE    SEVERAL    HEADS    RESPECTIVELY. 


CHAPTER  I. 

THE  BONES  AND  LIGAMENTS. 

THE  bones  are  arranged  into  those  of  the  thigh,  leg, 
and  foot,  which,  with  the  ligaments,  constitute  the  passive 

organs. 

SECTION    I. 

BONE  OF  THE  THIGH — OS  FEMORIS. 

The  femur  is  the  only  bone  belonging  to  the  thigh,  and 
is  the  longest  one  in  the  skeleton.  Situated  between  the 
pelvis  and  leg  obliquely,  it  presents  rather  a  twisted  ap- 
pearance, is  broad  below,  contracted  and  cylindrical  in  the 
centre,  and  thick  above.  It  is  composed  of  a  body  and  two 
extremities. 

The  body  is  convex  and  smooth  in  front,  concave  and 


OS  FEMORIS. 


743 


rough  behind.     The  front  is  covered  with  muscles.    The 
posterior  part  presents  a  rough  line  running  the  length  of 


FIG  240 


bone,  called  the  linea  as- 
pera.  This  line  has  an  exter- 
nal and  internal  ridge.  To 
the  former  is  attached  the  glu- 
teus  maximus,  the  short  head 
of  the  biceps,  and  the  vastus 
externus  muscles  ;  to  the  lat- 
ter the  vastus  internus,  tri- 
ceps, adductor,  and  pectineus. 
These  ridges  widen  below  and 
go  to  the  condyles  ;  above  they 
lead  to  the  trochanters.  In 
the  linea  aspera,  about  its 
middle,  is  seen  the  foramen 
for  conducting  the  nutritious 
artery. 

The  superior  extremity  of 
the  femur  presents  a  smooth, 
rounded  form,  called  the  head. 
It  looks  upward  and  inward, 
and  has  a  rough  depression  just  below  its  centre  for 
the  attachment  of  the  ligamentum  teres.  Just  below  the 
head,  the  bone  contracts  and  forms  the  neck,  which  connects 
with  the  body  or  shaft  by  an  ang]e  more  or  less  obtuse, 
varying  according  to  the  sex,  being  longer  and  more 
oblique  in  the  male  than  in  the  female. 

External  to  the  neck  there  is  a  large  process,  called  the 

FIG.  240,  A  represents  an  anterior  view  of  the  Femur,  a  Pit  for  attachj 
ment  of  round  ligament.  6  Head,  c  Neck,  d  Trochanter  major,  e  Tro- 
chanter  minor.  /  Point  of  attachment  of  the  capsular  ligament,  g  Shaft  or 
body,  h  External  condyle.  i  Internal  condyle.  j  Point  for  the  patella. 

FIG.  240,  B  represents  a  posterior  view  of  the  Femur,  a  Depression  for 
round  ligament,  b  Head,  c  Pit  for  the  rotatory  muscles,  d  Trochanter 
major,  e  Trochanter  minor.  /  Point  of  attachment  of  tendon  of  gluteus 
maximus.  g  g  Linea-aspera.  h  Point  of  attachment  for  the  gastrocnemiust 
i  External  condyle.  j  Point  of  attachment  of  anterior  crucial  ligament,  k 
Depression  for  posterior  crucial  ligament.  /  Point  of  attachment  of  internal 
lateral  ligament. 


744  OS  FEMORIS. 

trochanter  major,  wliich  is  continuous  with  the  outer  side  of 
the  shaft.  It  is  a  "broad,  rough,  convex  eminence,  over 
which  glides  the  tendon  of  the  gluteus  maximus  muscle; 
to  its  summit  is  attached  the  gluteus  medius;  to  its  ante- 
rior surface  the  gluteus  minimus,  and  to  its  posterior  the 
quadratus  femoris.  Internally  this  trochanter  presents  at 
its  base  a  pit  or  fossa  in  which  are  inserted  the  tendons  of 
the  rotator  muscles  of  the  thigh,  as  the  pyriformis,  gemelli, 
and  obturators  externus  and  internus.  On  the  inner  and 
posterior  side  of  the  upper  part  of  the  shaft  is  the  tro- 
chanter minor.  This  is  a  conical  projection  below  the  great 
trochanter,  and  gives  insertion  to  the  tendons  of  the  psoas 
magnus  and  iliacus  internus  muscles.  Between  the  two 
trochanters  are  seen  two  lines,  one  in  front  the  other 
behind,  called  inter-trochanteric  lines ,  to  which,  are  attached 
the  quadratus  femoris  muscle  and  the  capsular  ligament. 

The  lower  extremity  of  the  femur  is  large  and  broad, 
and  is  divided  into  an  external  and  internal  condyle  sepa- 
rated by  an  intervening  notch.  Each  condyle  presents  an 
outer  and  an  inner  face.  The  external  is  larger  and  more 
prominent;  its  articular  surface  is  higher  and  broader.  Its 
outer  surface  is  rough  for  the  attachment  of  the  external 
lateral  ligament ;  its  inner  surface  is  also  rough,  and  gives 
attachment  at  its  posterior  part  to  the  anterior  crucial  lig- 
ament. The  internal  condyle  is  longer  and  narrower  than 
the  external.  To  its  inner  side  are  attached  the  internal 
lateral  ligament  and  adductor  tendon,  and  to  its  outer  side 
the  posterior  crucial  ligament.  Both  condyles  have  a 
greater  convexity  behind  than  before.  The  inferior  ex- 
tremity presents  many  foramina  for  the  passage  of  vessels. 

The  body  of  the  femur  is  composed  of  compact  tissue 
traversed  by  a  medullary  canal,  while  its  extremities  are 
cellular. 

Its  development  is  from  five  points  ;  one  for  the  shaft,  one 
for  each  extremity,  and  one  for  each  trochanter.  It  is 
among  the  first  of  the  long  bones  to  ossify,  ossification 
being  observed  at  the  close  of  the  second  month.  In  the 
condyles  ossification  takes  place  during  the  ninth  month; 


TIBIA. 


T45 


FIG.  2  41. 


In  the  head  at  the  close  of  the  first  year  ;  in  the  great  tro- 
chanter  during  the  third  and  fourth  year,  and  in  the  lesser 
trochanter  about  the  thirteenth  or  fourteenth  year.     The 
different  processes  are  united  about  the  twentieth  year. 
The  femur  is  articulated  with  the  acetabulum,  tibia  and 

patella. 

SECTIO  N    II. 

BONES   OF  THE  LEG. 

1.  Tibia.  2.  Fibula.  3.  Patella. 

The  tibia  is  situated  on  the  inner  and  anterior  part  of 
the  leg,  and  is  next  to  the  femur  in  length.  Its  form  is 
triangular,  and  it  consists  of  a  body  and 
two  extremities. 

The  body  presents  three  edges — one  an- 
terior, called  the  crest  or  shin,  which  is 
superficial  and  sharp  ;  a  second  internal 
and  round;  and  a  third  external  for  the 
attachment  of  the  interosseous  ligament. 
It  also  presents  three  surfaces — one  internal 
and  superficial ;  a  second  external  and  con- 
cave; and  a  third  posterior,  covered  by  mus- 
cles. At  the  upper  part  of  the  body  is 
the  foramen  for  the  nutritious  artery. 

The  superior  extremity  of  the  tibia  is  large 
and  somewhat  oval  in  shape.  Its  femoral 
surface  is  smooth  and  covered  with  cartilage 
for  articulation.  It  is  divided  by  a  spine 
into  an  external  and  internal  surface.  The 
former  articulates  with  the  external  con- 
dyle,  and  is  circular  and  superficial;  the 
latter  with  the  internal  condyle,  and  is  oval  and  deeper 
The  spine  is  elevated  nearer  the  posterior  than  the 

FIG.  241  represents  an  anterior  view  of  the  Tibia  and  Fibula,  a  Shaft  of 
the  tibia.  6  Inner  tuberosity.  c  Outer  tuberosity.  d  Spinous  process,  e 
Tubercle  of  tibia.  /  Inner  surface  of  the  shaft,  g  Inferior  end  of  the  tibia. 
h  Internal  malleolus.  i  Shaft  of  the  fibula,  j  Superior  extremity  of  the 
fibula,  k  External  malleolus. 


T46  FIBULA. 

anterior  margin,  and  gives  attachment  in  front  and  be- 
hind it  to  the  anterior  and  posterior  crucial  ligaments. 
Just  below  the  articular  surface  the  tibia  presents  on  either 
side  a  prominence;  the  inner  is  for  the  attachment  of  the 
internal  lateral  ligament  and  tendon  of  the  semi-membra- 
nosus  muscle ;  the  outer  has  an  articular  surface  for  the 
head  of  the  fibula.  On  the  anterior  part  of  the  head  of 
the  tibia  a  tubercle  is  seen  for  the  insertion  of  the  liga- 
mentuni  patellas.  At  its  upper  part  there  is  a  bursa.  On 
the  inner  side  of  this  tubercle  a  concavity  is  seen  for  the 
insertion  of  the  tendons  of  the  sartorius,  gracilis,  and  semi- 
tendinosus  muscles. 

The  inferior  or  larsal  extremity  of  the  tibia  is  much 
smaller  than  the  upper.  Its  lower  surface  is  smooth,  con- 
cave and  rather  quadrilateral^  for  articulating  with  the 
upper  surface  of  the  astragalus.  Internally  there  is  a  thick 
vertical  process,  called  the  internal  malleolus,  which  has  its 
outer  surface  smooth  to  articulate  with  the  side  of  the 
astragalus,  and  its  inner  rough  for  the  attachment  of  the 
internal  lateral  ligament.  On  its  posterior  ridge  there  is 
a  groove  through  which  pass  the  tendons  of  the  tibialis 
posticus  and  flexor  communis.  On  the  external  margin  of 
the  lower  extremity  of  the  tibia  there  is  a  smooth  triangu- 
lar surface  for  articulation  with  the  lower  end  of  the  fibula. 

The  structure  of  the  tibia,  like  that  of  all  the  long  bones, 
is  compact  in  the  body  and  cellular  in  the  extremities. 

Its  development  is  from  three  points — one  for  the  body, 
and  one  for  each  extremity.  Ossification  is  seen  soon  after 
that  of  the  femur.  Soon  after  birth  it  takes  place  in  the 
head  of  the  bone,  and  in  the  second  year  in  the  inferior  ex- 
tremity. The  bone  is  complete  about  the  twenty-fifth  year. 

It  is  articulated  with  the  femur,  fibula,  and  astragalus. 

The  fibula  (Fig.  241)  is  a  slender  bone,  situated  upon  the 
outer  side  of  the  tibia,  arid  is  nearly  the  same  length  with 
that  bone.  It  consists  of  a  body  and  two  extremities. 

The  body  is  triangular  and  somewhat  twisted.  It  has 
three  angles  and  three  surfaces.  The  angles  or  ridges  are 
anterior,  posterior  and  internal.  The  surfaces  are  external. 


PATELLA.  747 

internal  and  posterior.  The  external  gives  origin  to  the 
peronei  muscles.  The  internal  is  divided  by  a  ridge  to 
which  the  interosseous  ligament  is  attached ;  and  the  sur- 
face in  front  of  the  ridge  is  for  the  origin  of  the  extensor 
muscles;  that  behind  the  ridge  for  the  tibialis  posticus. 
The  posterior  surface  is  covered  by  the  soleus,  and  below 
by  the  flexor  pollicis  pedis. 

The  superior  extremity  or  head  is  circular  and  small,  and 
presents  a  slight  cavity  for  articulating  with  the  external 
head  of  the  tibia.  Its  outer  surface  gives  attachment  to 
the  external  lateral  ligament  and  tendon  of  the  biceps 
muscle.  The  inferior  or  tarsal  extremity  is  larger  than 
the  upper,  and  ends  in  a  long,  oval  projection,  termed  the 
external  malleolus.  This  process  internally  is  smooth  and 
triangular  for  articulating  with  the  astragalus;  a  little 
above  it  is  rough  for  connecting  with  the  tibia ;  posteriorly 
it  is  grooved  for  the  tendons  of  the  peronei  muscles ;  exte- 
riorly it  is  rough  and  superficial  and  gives  attachment  to 
ligaments.  The  centre  of  the  shaft  contains  the  nutritious 
foramen. 

The  structure  is  the  same  as  that  of  the  tibia,  being 
compact  in  its  shaft  and  cellular  in  its  extremities. 

Its  development  is  by  three  points ;  one  for  the  shaft,  and 
one  for  each  extremity.  Ossification  begins  soon  after  it 
does  in  the  tibia;  during  the  second  year  the  lower  epiph- 
ysis  begins  to  ossify,  and  in  the  fourth  or  fifth  year  the 
upper  epiphysis,  the  bone  being  completed  about  the 
twenty-fifth  year.  The  fibula  is  articulated  with  the  tibia 
and  astragalus. 

The  patella  or  rotula  is  situated  in  front  of 
the  knee  joint,  and  is  regarded  as  a  sesamoid 
bone,  developed  in  the  tendon  of  the  exten- 
sor femoris  muscle.  Its  shape  is  triangular ; 
its  base  above  receives  the  tendons  of  the 
extensor  muscles ;  its  apex  below  is  pointed, 

FIG.  242  represents  the  Patella,  a  6  Point  of  attachment  of  the  tendon  of 
the  triceps-extensor  and  femoris  muscle,  c  Point  of  attachment  of  the  liga- 
mentum  patella. 


748 


TARSUS. 


and  has  the  ligamentum  patellae  attached  to  it.  Its  ante- 
rior surface  is  convex,  perforated  with  foramina,  and  has 
a  bursa.  Its  posterior  is  smooth,  covered  with  cartilage? 
and  doubly  concave  for  articulation  with  the  condyles  of 
the  femur.  It  is  developed  by  a  single  point,  during  the 
third  year. 

SECTION   III. 
BONES  OF  THE  FOOT,    (Fig.   243.) 

A  FIG.  243.          B  These    are    divided 

into  the  tarsus,  meta- 
tarsus, and  phalanges. 
The  tarsus  consists  of 
seven  bones — the  astra- 
galus, os  colds,  os  navi- 
culare,  internal,  external 
and  middle  cuneiform, 
and  the  cuboid  bone. 

The    astragalus     (<w- 
tfpaycaoj,  a  die)  is  situa- 
ted  between  the  tibia 
and  os  calcis,  occupy- 
ing the  upper  portion 
of  the  instep.    Its  up- 
per surface  is  smooth, 
•    and  arched  for  articu- 
lating with  the  tibia.    Its  lower  surface  presents  two  artic- 

FIG.  243,  A  represents  the  Dorsal  surface  of  the  Foot,  a  Astragalus.  6 
Point  of  articulation  with  the  naviculare.  c  Os-calcis.  d  Os-naviculare,  or 
scaphoides.  e  Internal  cuneiform.  /  Middle  cuneiform,  g  External  cunei- 
form, h  Cuboid  bone,  i  Metatarsal  bones,  j  First  phalanx  of  the  great  toe. 
k  Second  phalanx  of  the  great  toe.  I  m  n  First,  second,  and  third  phalanges 
of  the  other  toes. 

FIG.  243,  B  represents  the  Plantar  surface  of  the  Foot,  a  Lesser  apophysis 
of  the  calcis.  6  Exterior  edge  of  calcis.  c  Groove  for  the  tendon  of  the 
flexor  longus  pollicis  pedis.  d  Anterior  portion  of  astragalus,  e  Naviculare. 
/  Its  inner  side  and  tuberosity.  g  Internal  cuneiform,  h  Middle  cuneiform. 
t  External  cuneiform  bone,  j  Cuboid  bone,  k  Groove  for  tendon  of  pero- 
neus-longus.  II  Metatarsal  bones,  m  n  o  First,  second,  and  third  phalanges 
of  the  toes,  p  Last  phalanx  of  the  great  toe. 


TARSUS.  749 

ular  faces — one  anterior  and  small,  the  otlier  posterior  and 
large,  separated  by  a  deep  fossa  for  the  interosseous  liga- 
ment, and  both  faces  articulating  with  the  os  calcis.  The 
front  of  the  astragalus  is  smooth  and  rounded  for  articula- 
ting with  the  naviculare.  The  posterior  is  grooved  for  the 
tendon  of  the  flexor  pollicis.  Its  outer  surface  is  smooth 
for  articulating  with  the  malleolus  externus.  Its  inner 
surface  articulates  with  the  malleolus  internus. 

The  os  colds — calx,  the  heel,  (Fig.  243,)  is  readily  dis- 
tinguished by  being  the  largest  bone  of  the  tarsus,  and 
being  situated  at  its'  posterior  and  lower  part.  Its  form  is 
oblong.  Its  upper  surface  has  two  faces,  separated  by  a 
groove,  for  articulating  with  the  astragalus.  Its  lower 
surface  is  rather  concave,  and  bounded  posteriorly  by  two 
tubercles  which  give  attachment  to  the  aponeurosis  plan- 
taris  and  muscles  of  the  foot.  Its  anterior  extremity  artic- 
ulates with  the  cuboides  by  a  slightly  concave  surface.  Its 
posterior  extremity  is  convex  and  rough,  forms  the  heel, 
has  a  bursa,  and  receives  the  insertion  of  the  tendo  Achittis. 
Externally  the  calcis  is  rather  flat  and  grooved  for  the  pas- 
sage of  the  peroneal  tendons  ;  and  internally  it  is  hollowed 
and  arched  for  the  passage  of  the  flexor  tendons,  tibialis 
posticus,  and  plantar  vessels  and  nerves.  It  articulates 
with  the  astragalus  and  cuboid. 

The  o,s  naviculare  or  scaplioides  (Fig.  243)  occupies  a  mid- 
dle position  at  the  upper  and  inner  portion  of  the  tarsus. 
Its  form  is  oval.  Its  posterior  surface  is  concave  and  smooth 
for  articulating  with  the  head  of  the  astragalus.  Its  ante- 
rior surface  is  divided  into  three  articular  facets  for  the  three 
cuneiform  bones.  Its  inferior  surface  gives  insertion  to  the 
tibialis  posticus,  and  its  external  articulates  with  the  cuboid. 

This  bone  articulates  with  five, — the  astragalus,  cuboid, 
and  three  cuneiform  bones. 

The  os  cuboides  (Fig.  243)  is  situated  on  the  outside  of 
the  naviculare,  and  occupies  the  external  and  anterior  por- 
tion of  the  tarsus.  Its  form  is  somewhat  cubical.  Its  up- 
per surface  is  rough  and  flat ;  its  lower,  irregular,  rough, 
and  grooved  for  the  tendon  of  the  peronetis-longus.  Its 


METATARSUS, 

anterior  surface  has  two  smooth  divisions  for  articulating 
with  the  fourth  and  fifth  metatarsal  bones ;  its  posterior  is 
smooth  and  concave  to  articulate  with  the  os  calcis. 

It  articulates  with  the  os  calcis,  naviculare,  external  cune- 
iform, and  two  external  metatarsal  bones. 

The  cuneiform  bones  (Fig.  243)  are  situated  on  the  ante- 
rior portion  of  the  tarsus,  and  are  wedge-shaped.  The 
internal  is  the  largest,  and  is  articulated  in  front  and  to 
the  outside  to  the  middle  cuneiform,  and  to  the  first  and 
second  metatarsal  bones ;  behind  it  articulates  with  the 
naviculare,  and  below  it  gives  attachment  to  the  tendon  of 
the  tibialis  posticus.  The  middle  cuneiform  is  situated 
between  the  other  two,  is  the  smallest,  and  articulates  also 
with  the.  naviculare  behind,  and  the  second  metatarsal  in 
front.  The  external  cuneiform  is  next  to  the  cuboid,  and 
articulates  in  front  with  the  third  metatarsal  bone,  behind 
with  the  naviculare,  on  the  inside  with  the  middle  cunei- 
form, and  on  the  outside  with  the  cuboid. 

The  tarsus  is  developed  by  a  single  point  for  each  bone, 
and  ossification  has  been  observed  in  the  following  order: 
in  the  sixth  month  in  the  calcis,  seventh  month  in  the 
astragalus,  tenth  month  in  the  cuboid,  first  year  in  the 
external  cuneiform,  third  year  in  the  internal  cuneiform, 
fourth  year  in  the  middle  cuneiform  and  naviculare. 

METATARSUS,   (Fig.  243.) 

The  metatarsal  bones  are  five  in  number. 

The  first  corresponds  to  the  great  toe,  and  is  the  shortest 
and  thickest.  It  is  convex  above  and  concave  below.  Its 
anterior  extremity  is  round  and  smooth  for  articulating 
with  the  first  phalanx  of  the  great  toe ;  its  posterior 
extremity  is  concave^  to  articulate  with  the  internal  cunei- 
form bone.  The  second  metatarsal  bone  is  the  longest,  and 
articulates  at  its  upper  extremity  with  the  three  cuneiform 
bones ;  its  lower  extremity  articulates  with  the  first  pha- 
lanx of  the  second  toe.  The  third  metatarsal  bone  is  shorter 
than  the  second,  and  articulates  at  its  tarsal  extremity 
with  the  third  cuneiform,  and  by  its  sides  at  this  extremity 


LIGAMENTS  OF  THE  HIP  JOINT. 

witli  the  adjoining  metatarsal  bones.  The  fourth  metatarsal 
is  shorter  than  the  third,  and  articulates  with  the  cuboid, 
and  by  the  inner  side  of  its  base  with  the  third  cuneiform 
bone.  The  fifth  metatarsal  is  the  shortest  except  the  first, 
and  articulates  above  with  the  cuboid,  and  presents  on  the 
outside  of  this  joint  a  projecting  tubercle.  All  the  meta- 
tarsal bones  have  a  similar  structure,  consisting  of  the 
compact  and  cellular. 

The  phalanges  (Fig.  243)  are  three  to  each  toe,  except  the 
great  toe,  which  has  but  two — consequently  there  are  four- 
teen in  all.  These,  like  the  fingers,  have  each  a  body  or 
shaft  and  two  extremities. 

The  first  phalanges  are  the  longest ;  their  upper  extremity 
is  concave  for  articulating  with  the  head  of  the  metatarsal 
bones.  The  base  of  the  first  phalanx  of  the  great  toe  gen- 
erally has  two  sesamoid  bones. 

The  second  phalanges — the  great  toe  having  none — are 
very  short,  and  their  upper  extremities  are  concave  for 
articulating  with  the  convex  end  of  the  first  phalanx. 

The  third  phalanges,  except  that  of  the  great  toe,  are 
small.  They  articulate  by  their  upper  extremity  with  the 
second  phalanx,  and  have  their  upper  surfaces  broad  and 
rough  for  the  reception  of  the  nails. 

SECTION    IV. 
LIGAMENTS   OF   THE   INFERIOR   EXTREMITY. 

Ligaments  of  the  hip  joint. — The  bones  of  this  joint  com- 
prise the  head  of  the  femur  and  the  acetabulum,  both  of 
which  are  covered  with  cartilage  and  secured  by  the  fol- 
lowing ligaments: 

The  capsular  ligament  is  one  of  the  strongest  and  most 
perfect  of  the  kind  in  the  body.  It  is  connected  above  to 
the  outer  circumference  of  the  acetabulum,  and  below  to  the 
roots  of  both  trochanters ;  thus  enclosing  the  whole  neck  of 
the  femur.  It  is  longer  behind  and-below  than  at  any  other 
point,  but  thicker  and  stronger  above  and  in  front  from 
the  presence  of  an  accessory  ligament,  termed  ilio-femoral. 
This  extends,  as  a  strong  fibrous  band,  from  the  inferior 


T52 


LIGAMENTS  OF  THE  KNEE  JOINT. 


spinous  process  of  the  ilium,  incorporates  itself  with  the 
anterior  capsular  ligament,  and  goes  to  be  attached  to  the 
F,G.  244.  front  of  the  femur,  near 

the  trochanter  minor. 

The  cotyloid  ligament 
(Fig.  244)  consists  of  fibro- 
cartilage,  placed  round 
the  margin  of  the  aceta- 
bulum  to  deepen  its  cavi- 
ty. Its  fibres  are  circular 
and  strong,  and  thicker 
above  than  behind.  Its 
free  edge  is  sharp,  and 
within  the  capsular  liga- 
ment it  is  connected  with 
some  ligamentous  fibres 
which  stretch  across  the 
notch  of  the  acetabulum,  called  the  transverse  ligament 

Ligamentum  teres,  round,  or  interarticular  ligament,  (Fig. 
244.) — This  is  a  round  or  triangular  cord,  about  an  inch 
and  a  half  long,  within  the  capsular.  It  is  seen,  by  open- 
ing the  latter,  to  be  attached  at  one  extremity  to  the 
depression  in  the  head  of  the  femur,  and  by  the  other 
which  bifurcates,  to  the  depression  and  borders  of  the 
notch  of  the  acetabulum. 

The  synovial  membrane  forms  a  complete  sac,  which  lines 
the  acetabulum,  covers  the  cotyloid  and  round  ligament, 
and  the  head  and  neck  of  the  femur ;  it  also  adheres  to 
the  reddish  fatty  mass  filling  the  rough  surface  of  the 
acetabulum. 

LIGAMENTS  OF  THE  KNEE-JOINT. 

The  bones  comprising  this  joint  are  the  condyles  of  the 
femur,  the  patella,  and  head  of  the  tibia.  This  is  a  very 
complicated  joint,  including  a  variety  of  ligaments. 

FIG.  244  represents  the  ligaments  of  the  Hip  Joint,  a  Posterior  sacro  iliac 
ligament.  6  Greater  sacro  sciatic  ligament,  c  Lesser  sacro  sciatic  ligament. 
d  Greater  sacro  sciatic  notch,  c  Lesser  sacro  sciatic  notch.  ^Cotyloid  liga- 
ment, g  Ligamentum  teres.  h  Point  of  attachment  of  capsular  ligament. 
i  Obturator  ligament. 


LIGAMENTS  OP  THE  KNEE  JOINT. 


753 


The  ligamentum  patellce  (Fig.  245)  is  attached  above  to  the 
inferior  end  of  the  patella,  and  below  to  the  tubercle  of  the 
tibia.  It  consists  of  strong,  A  FIG.  245.  B 

thick,  broad  and  parallel 
fibres,  and  is  regarded  as 
a  continuation  of  the  ten- 
don of  the  recti  muscles. 
Theligamentof  Winslow, 
or  posterior  ligament,  is 
situated  on  the  posterior 
part  of  the  joint,  and 
forms  a  broad  membra- 
nous expansion  from  the 
tendon  of  the  semi-mem- 
branosus  muscle,  reaching  from  the  inner  side  of  the  head 
of  the  tibia  to  the  external  condyle  of  the  femur. 

The  internal  lateral  ligament  (Fig.  245)  consists  of  a  flat- 
tened fasciculus  of  fibres  which  extend  from  the  internal 
condyle  of  the  femur  to  the  inner  side  of  the  head  of  the 
tibia  and  semilunar  cartilage. 

The  external  lateral  ligament  (Fig.  245)  extends  frequently 
as  a  double  cord  from  the  outer  side  of  the  external  condyle 
to  the  head  of  the  fibula. 

The  anterior  crucial  ligament  extends  from  the  inner  side 
and  posterior  part  of  the  external  condyle,  obliquely  for- 
ward and  inward  to  the  depression  in  front  of  the  spine  of 
the  tibia. 

The  posterior  crucial  ligament  (Fig.  246)  extends  from  the 
outer  side  and  front  of  the  inner  condyle  to  the  depression 
on  the  back  of  the  spine  of  the  tibia.  These  crucial  ligaments 

FIG.  245,  A  represents  the  ligaments  upon  the  front  and  sides  of  the  Knee 
Joint,  a  Tendon  of  the  quadriceps  femoris  muscle.  6  Patella,  c  Ligament  of 
patella,  d  d  Synovial  membrane,  e  Internal  lateral  ligament.  /  External 
lateral  ligament,  g  Ligament  connecting  the  fibula  with  the  tibia. 

FIG.  245,  B  represents  the  ligaments  on  the  back  part  of  the  Knee  Joint. 
1  Ligament  of  Winslow.  2  Tendon  of  semi-membranosus  muscle.  3  Its 
insertion.  4  The  portion  of  it  which  goes  under  the  internal  lateral  ligament. 
5  Internal  lateral  ligament.  6  External  lateral  ligament.  7  Fibres  of  exter- 
nal lateral  ligament.  8  Section  of  tendon  of  popliteus  muscle.  9  Superior 
posterior  peroneo-fibial  ligament. 
48 


754 


LIGAMENTS  OF  THE  KNEE  JOINT. 


are  very  strong,  and  are  relaxed  when  the  leg  is  bent,  but 
tense  when  it  is  extended. 

The  semilunar  carti- 
lages (Fig.  246)  are  sit- 
uated upon  the  superior 
articular  surface  of  the 
tibia,  and  are  two  in 
number,  an  external  and 
an  internal.  The  outer 
edge  of  each  is  thick, 
the  inner  edge  thin, 
sharp,  and  loose.  The 
upper  surface  of  each  is 
concave,  the  lower  sur- 
face flat.  The  external 
receives  the  head  of  the  outer  condyle,  and  is  more  circular 
and  movable  than  the  internal,  which  receives  the  inner  con- 
dyle. The  circumference  of  the  semilunar  cartilages  is 
attached  to  the  margin  before  and  behind  the  spine  of  the 
tibia,  and  to  the  lateral  ligaments.  These  cartilages  are 
connected  in  front  by  fibres  called  the  transverse  ligament. 
The  synovial  membrane  is  both  extensive  and  complex. 
It  covers  the  head  of  the  tibia,  both  surfaces  of  the  semi- 
lunar  cartilages,  the  condyles  of  the  femur,  the  inner  sur- 
face of  the  patella,  the  crucial  ligaments,  and  posterior 
surface  of  the  tendons  of  the  recti  muscles.  It  gives  off 
several  reflections  which  have  been  styled  ligaments.  The 
double  fold  of  this  membrane  upon  a  quantity  of  fat  behind 

FIG.  246,  A  represents  the  Knee  Joint  laid  open.  1  Lower  end  of  femur. 
2  Anterior  crucial  ligament.  3  Posterior  crucial  ligament.  4  Fasciculus 
attached  to  semilunar  cartilages.  5  Point  where  ligamentum  mucosum  is 
attached.  6  Internal  semilunar  cartilage.  7  External  semilunar  cartilage. 
8  Ligamentum  patella.  9  Bursa  laid  open.  10  Superior  peroneo-tibial 
articulation.  11  Interosseous  ligament. 

FIG.  246,  B  represents  a  Vertical  section  of  Knee  Joint.  1  Cellular  struc- 
ture of  lower  end  of  femur.  2  Common  tendon  of  the  extensor  muscles,  at- 
tached to  the  patella.  3  Patella.  4  Ligamentum  patellae.  5  Cancellated  struc- 
ture of  tibia.  6  Bursa  between  tibia  and  ligament  of  patella.  7  Adipose  matter 
projecting  into  the  joint.  8  Synovial  membrane.  9  One  of  the  ligamenta  alaria. 
10  Ligamentum  mucosum.  11  Anterior  crucial  ligament.  12  Posterior  crucial 
ligament. 


LIGAMENTS   OF  THE  ANKLE  JOINT. 


755 


the  patella,  receives  the  name  of  external  and  internal  alar 
ligaments,  and  another  fold  passing  from  this  fatty  matter 
behind  the  patella  upward  and  backward  to  the  hollow  be- 
tween the  condyles,  is  called  ligamentum  mucosum.  (Fig.  246.) 

The  tibia  and  fibula  are  connected  at  their  extremities 
by  the  superior  and  inferior  tibio-fibular  articulations,  and 
their  shafts  by  an  interosseous  membrane. 

The  superior  articulation  is  formed  of  an  anterior  and  a 
posterior  ligament,  which  pass  from  the  head  of  the  tibia 
to  the  head  of  the  fibula.  There  is  also  a  distinct  synovial 
membrane.  The  inferior  articulation  has  also  an  anterior 
and  a  posterior  ligament,  which  pass  from  the  lower  ex- 
tremity of  the  fibula  to  contiguous  portions  of  the  tibia. 

A  synovial  membrane  is  seen  communicating  with  the 
ankle  joint. 

The  interosseous  ligament  fills  the  space  between  the  two 
bones,  and  passes  from  the  external  edge  of  the  tibia  to 
the  corresponding  edge  of  the  fibula. 

LIGAMENTS   OF   THE   ANKLE   JOINT. 

The  bones  com-  A        FlG-  247« 

posing  this  joint 
are  the  astrag- 
alus below,  and 
the  tibia  and 
fibula  above. 

The    anterior 
ligament ,  not  al- 
ways    distinct, 
extends  from  the  anterior  margin  of  the  tibia  to  the  upper 
part  of  the  astragalus. 

FIG.  247,  A  represents  Ligaments  at  the  inner  side  of  the  Ankle  Joint,  a 
Internal  malleolus.  6  6  Part  of  astragalus,  c  Os  calcis.  d  Scaphoides.  e 
Internal  cuneiform  bone.  /  Deltoid  or  internal  lateral  ligament,  g  Synovial 
capsule,  h  Tendo-Achillis. 

FIG.  247,  B  represents  Ligaments  on  the  outer  side  of  Ankle  Joint,  a  Tibia. 
b  External  malleolus.  c  c  Astragalus,  d  Os  calcis.  e  Cuboides.  fg  h  Exter- 
nal lateral  ligament  arranged  into  three  fasciculi,  anterior,  middle,  and  poste- 
rior, i  Capsular  ligament. 


756 


LIGAMENTS  OF  THE  FOOT. 


The  deltoid  or  internal  lateral  ligament  (Fig.  247)  extends 
from  the  inferior  margin  of  the  malleolus  intermis  in  a 
radiated  manner  to  the  os  calcis,  naviculare,  and  astrag- 
alus. 

The  external  lateral  ligament  is  composed  of  three  distinct 
fasciculi,  an  anterior,  posterior,  and  middle,  all  of  which 
extend  from  the  external  malleolus  to  the  astragalus  and 
os  calcis.  There  is  the  usual  synovial  membrane. 

LIGAMENTS  OF  THE  FOOT. 

These  comprise  the  tarsus,  metatarsus,  and.  phalanges. 

The  ligaments  of  the  tarsus  are  divided  into  the  dorsal 
FIG.  248.  and  plantar.     An   interosseous   ligament 

connects  the  astragalus  and  os  calcis,  and 
is  situated  in  the  fossa  between  their  ar- 
ticular surfaces,  and  &  posterior  ligament 
also  unites  them  behind. 

The  calcaneo-scaplioid  (Fig.  248)  is 
double,  consisting  of  an  internal  and  ex- 
ternal portion;  both  of  these  are  on  the 
plantar  surface.  The  internal  consists  of 
a  broad  fibre-cartilaginous  band,  which 
extends  from  the  lesser  tubercle  of  the  os 
calcis  to  the  lower  and  inner  surface  of 
the  naviculare.  It  forms  a  trochlea  for 
the  play  of  the  tendons  of  the  flexor  lon- 
gus  pollicis  and  flexor  digitorum.  The 
external  portion  extends  from  the  greater 
tubercle  of  the  calcis  to  the  external  under  surface  of  the 

naviculare. 

The  calcaneo-cuboid  (Fig.  248)  is  also  double.  The  plantar 
portion  is  large,  and  extends  from  the  under  surface  of 
the  calcaneum  to  the  cuboides,  and  even  as  far  as  the  third 

FIG.  248  represents  the  Ligaments  on  the  sole  of  the  Foot,  a  Inferior  sur- 
face of  the  calcis.  b  Astragalus,  c  Scaphoides.  d  e  Calcaneo-cuboid  liga- 
ment. /  Calcaneo-scaphoid  ligament,  g  Plantar  ligaments,  h  h  Tendon  of 
Peroneus  longus.  i  i  Tarso-metatarsal  plantar  ligaments,  j  Capsular  liga- 
ment of  first  joint  of  the  great  toe.  fe  Lateral  ligaments  of  the  first  joints  of 
the  toes 


MUSCLES  OF  THE  INFERIOR  EXTREMITY. 

and  fourth  metatarsal  bones.  The  dorsal  portion  consists 
of  thin  broad  layers  of  fibres,  which  extend  from  the  ante- 
rior upper  surface  of  the  os  calcis  to  the  upper  surface  of 
the  cuboides. 

The  navicular  bone  and  cuboid  are  united  by  an  inter- 
osseous  ligament,  and  the  naviculare  and  three  cuneiforme 
bones  are  connected  by  a  triple  ligament  passing  from  one 
to  the  other.  A  synovial  membrane  belongs  to  all  the 
articular  surfaces. 

The  ligaments  of  the  metatarsus  consist  chiefly  of  trans- 
verse dorsal  and  plantar  fibres,  which  pass  from  the  tarsal 
to  the  metatarsal  bones  on  the  top  and  sole  of  the  foot,  and 
interosseous  ligaments  situated  at  the  sides  of  the  tarsal 
ends  of  the  four  metatarsal  bones  of  the  small  toes. 

The  ligaments  of  the  phalanges  have  a  very  similar 
arrangement  with  those  of  the  fingers,  and  it  may  there- 
fore simply  be  remarked  that  the  anterior  ends  of  each 
metatarsal  bone  are  connected  by  transverse  fibres,  called 
anterior  plantar  ligaments.  They  are  received  into  the 
cavities  of  the  first  phalanges,  being  furnished,  as  all  the 
phalanges,  with  lateral  ligaments  and  synovial  membranes. 


CHAPTER  II. 

ACTIVE  ORGANS  OF  THE  INFERIOR  EXTREMITY. 

SECTION    I. 
MUSCLES   OF   THE  INFERIOR   EXTREMITY. 

Muscles  of  the  Thigh. — Those  on  the  anterior  and  internal 
thigh.  The  psoas  and  iliacus  internus  muscles  are  described 
under  another  head. 

Dissection. — Make  an  incision  from  the  anterior  superior 
spinous  process  of  the  ilium,  along  Poupart's  ligament  to 
the  spine  of  the  pubis.  From  the  centre  of  this  make  a 
second  down  the  front  and  middle  of  the  thigh,  to  a  little 
below  the  knee ;  cross  this  latter  by  two  transverse  incisions, 
one  at  the  upper,  the  other  at  the  lower  third  of  the 


Y58 


MUSCLES  OF  THE  THIGH. 


thigh.  Turn  aside  first  the  integument,  then  the  super- 
ficial fascia,  bringing  in  view  the  fascia  lata,  which  should 
be  carefully  examined.  The  fascia  lata  being  turned  off, 
the  muscles  are  exposed. 

FIG.  249.  The  tensor  vaginas  femoris  (Fig.  249) 

arises  from  the  outer  portion  of  the  ante- 
rior superior  spinous  process,  tendinous ; 
becomes  fleshy  as  it  descends,  and  is  in- 
serted thin  and  broad  between  the  two 
layers  of  the  fascia  lata,  below  the  trochan- 
ter  major,  on  the  outer  side  of  the  thigh. 
Function. — To  stretch  the  fascia  and 
turn  the  foot  inward. 

The  sartorius — tailor's  muscle — (Fig- 
249)  arises  from  the  anterior  superior  spi- 
nous process  of  the  ilium  by  a  short  ten- 
don, and  from  the  notch  below.  Becom- 
ing fleshy  it  forms  a  flat  riband-like  mus- 
cle, which  takes  a  spiral  course  to  the 
inner  side  of  the  thigh  ;  thence  to  the  back 
of  the  inner  condyle,  forward  by  the  head 
of  the  tibia,  to  be  inserted  into  the  inner 
side  of  its  tubercle  by  a  broad  tendon 
which  is  continued  into  the  fascia  of  the 
leg.  In  its  course  it  crosses  the  rectus, 
vastus  internus,  and  triceps  adductor,  and 
is  the  longest  muscle  in  the  body. 

Function. — To  bend  the  leg  and  turn  it  obliquely  inward. 
The  action  of  both  muscles  is  to  cross  the  legs  after  the 
manner  of  tailors,  which  has  given  the  name  to  the  muscle. 
The  rectus  femoris  (Fig.  249)  arises  by  two  tendons— one 
round,  from  the  anterior  inferior  spinous  process  of  the 
ilium,  the  other  broad,  from  the  superior  and  outer  border 

FIG.  249  represents  the  Muscles  on  the  anterior  part  of  the  Thigh.  1  Crest 
of  the  ilium.  2  Anterior  superior  spinous  process.  3  Gluteus  medius. 
4  Tensor  vaginae  femoris.  5  Sartorius.  6  Rectus  femoris.  7  Vastus  exter- 
nus.  8  Vastus  internus.  9  Patella.  10  Iliacus  internus.  11  Psoas  magnus. 
12  Pectineus.  13  Adductor  longus.  14  Adductor  magnus.  15  Gracilis. 


MUSCLES  OP  THE  THIGH.  759 

of  the  acetabulum.  It  forms  a  complete  penniform  mus- 
cle, which,  running  in  front  of  the  thigh,  is  inserted,  by  a 
strong,  flat  tendon,  into  the  superior  margin  of  the  patella. 

Function. — To  extend  the  leg. 

The  vastus  externus  (Fig.  249)  arises,  tendinous  and 
fleshy,  from  the  root  of  the  great  trochanter,  and  from  the 
whole  length  of  the  linea  aspera  at  its  outer  edge,  from 
the  ridge  leading  to  the  external  condyle,  and  from  the 
outer  surface  of  the  femoral  hone.  Its  fibres  descend  ob- 
liquely, and  are  inserted  into  the  outer  edge  of  the  tendon 
of  the  rectus,  and  outer  edge  of  the  patella.  This  is  a  large 
muscle  upon  the  outer  thigh.  Function. — To  extend  the 
leg,  also  to  turn  the  knee  outward. 

The  vastus  internus  (Fig.  249)  arises  from  the  front  of 
the  femur,  at  the  trochanter  minor,  and  covers  all  the 
inner  side  of  this  bone ;  arises  also  from  the  whole  inner 
edge  of  the  linea  aspera,  and  from  the  ridge  going  to  the 
inner  condyle.  Its  fibres  descend  obliquely,  and  are  in- 
serted into  the  inner  edge  of  the  tendon  of  the  rectus,  and 
inner  edge  of  the  patella.  It  is  smaller  and  shorter  than 
the  vastus  externus.  Function. — To  extend  the  leg. 

The  crurceus  arises  fleshy  from  all  the  front  of  the  femo- 
ral bone  and  its  outside,  to  the  linea  aspera.  It  is  uncon- 
nected with  the  bone,  on  its  inner  side;  for  about  the 
breadth  of  an  inch,  and  extending  thus  nearly  the  whole 
length  of  the  shaft.  It  is  behind  the  rectus,  and  over- 
lapped by  the  two  vasti.  Its  insertion  is  into  the  upper 
edge  of  the  patella,  behind  the  tendon  of  the  rectus. 

Function. — To  extend  the  leg.  The  last  three  muscles 
receive  the  name  of  triceps  extensor  femoris ,  and,  including 
the  rectus ,  are  called  quadriceps  femoris.  A  few  muscular 
fibres  of  the  cruraeus  are  seen  going  to  the  synovial  mem- 
brane of  the  joint,  and  take  the  name  of  sub-crurceus.  A 
large  bursa  is  found  behind  the  cruraaus,  just  above  the 
patella,  and  sometimes  on  the  patella. 

The  gracilis  (Fig.  249)  arises  from  the  inner  edge  of  the 
descending  ramus  of  the  pubis  and  lower  half  of  the  sym- 
physis,  by  a  broad,  thin  tendon,  which  descends  fleshy  and 


760  MUSCLES  OF  THE  THIGH. 

riband-like  from  the  pelvis  to  the  leg,  and  being  the  inner 
muscle  of  the  thigh,  forms  at  its  lower  part  a  round  tendon, 
which  goes  behind  the  internal  condyle  and  head  of  the 
tibia,  and  then  curves  forward  beneath  the  tendon  of  the 
sartorius  to  be  inserted  at  the  lower  and  lateral  part  of 
the  tubercle  of  the  tibia.  Function. — To  flex  the  leg;  also 
to  adduct  it. 

The  pectineus  or  pectinalis  (Fig.  249)  arises  fleshy  from 
the  upper  concave  surface  of  the  pubis,  forms  a  short,  flat, 
triangular  muscle,  situated  at  the  inner  and  upper  part  of 
the  thigh,  and  is  inserted  tendinous  into  the  linea  aspera, 
just  below  the  trochanter  minor,  function. — To  turn  the 
thigh  inward  and  forward. 

The  triceps  adductor  femoris  (Fig.  249)  consists  of  three 
portions,  viz : 

The  adductor  longus — which  arises  from  the  anterior  upper 
surface  of  the  pubes  between  its  spine  and  symphysis  by  a 
short  round  tendon — forms  a  flat,  triangular  muscle,  situ- 
ated between  the  gracilis  and  pectinalis,  and  is  inserted 
broad  into  the  middle  third  of  the  linea  aspera.  Func- 
tion.— To  bring  the  thigh  inward  and  forward. 

The  adductor  brevis  arises  tendinous  from  the  anterior 
lower  surface  of  the  pubes,  is  beneath  the  adductor  longus 
and  pectinalis,*and  goes  to  be  inserted  into  the  superior 
third  of  the  linea  aspera.  Function. — The  same  as  the  last- 

The  adductor  magnus  arises  fleshy  from  the  descending 
ramus  of  the  pubis,  and  ram  us  of  the  ischium  as  far  as  its 
tuberosity,  covering  the  surface  between  the  thyroid  fora- 
men and  margin  of  the  bone.  It  is  much  the  largest  and 
longest  of  the  adductors,  and  is  inserted  fleshy  and  tendi- 
nous into  the  whole  of  the  linea  aspera,  and  by  a  round 
tendon  continued  into  the  internal  condyle  of  the  femur. 

Function. — The  same  as  the  last. 

MUSCLES   ON   THE   POSTERIOR   THIGH. 

Dissection. — Make  a  longitudinal  incision  along  the  mid- 
dle of  the  back  of  the  thigh,  and  a  transverse  one  at  the 
centre. 


MUSCLES  OF  THE  THIGH. 


761 


The  ylutei  are  described  along  with  the  rotators  of  the 
thigh,  under  the  head  of  muscles  of  the  pelvis,  which  see. 

The  biceps  flexor  cruris  arises  by  two  heads ;  the  long 
head  by  a  short  tendon,  in  common  with  the  semi-tendino- 
sus,  from  the  back  part  of  the  tuberosity  of  the  ischium ; 
the  short  head  comes  from  the   lower          FIG.  250. 
third  of  the  linea  aspera  and  joins  the 
long.     A  strong  tendon  is  thus  formed, 
constituting  the  outer  hamstring,  which 
goes  to  be  inserted  into  the  head  of  the 
fibula.     A  bursa  is  seen  between  this 
tendon   and   the  external  lateral  liga- 
ment.    Function. — To  bend  the  leg. 

The  semi-tendinosus  (Fig.  250)  arises 
from  the  tuberosity  of  the  ischium  in 
common  with  the  long  head  of  the  biceps, 
to  which  it  adheres  for  three  or  four 
inches,  becomes  large  and  fleshy,  and 
ends  in  a  round,  long  tendon,  constitut- 
ing one  of  the  inner  hamstring  muscles, 
which  goes  behind  the  internal  condyle 
to  be  inserted  into  the  side  of  the  tibia 
below  its  tubercle.  Function. — To  bend 
the  leg. 

Thesemi-membranosus  (Fig.  250)  arises 
from  the  tuberosity  of  the  ischium,  at 
its  upper  and  outer  part  tendinous,  soon  forms  a  mem- 
branous expansion,  and  becoming  fleshy,  ends  below  in 
a  tendon  constituting  the  other  inner  hamstring,  which 
passes  behind  the  internal  condyle,  to  be  inserted  into  the 
back  and  inner  part  of  the  head  of  the  tibia,  just  below  its 
joint.  At  this  point  the  tendon  sends  off  a  broad  aponeu- 
rosis,  covering  the  back  of  the  joint,  and  passing  beneath 

FIG.  250  represents  the  Muscles  on  the  Posterior  Thigh,  a  Gluteus  medius. 
6  Gluteus  maximus.  c  Fascia  lata.  d  Long  head  of  the  biceps  flexor  cruris. 
t  Short  head  of  the  same  muscle.  /Semitendinosus.  g  g  Semi-membranosus- 
h  Gracilis.  i  Adductor  magnus.  j  Sartorius.  k  Popliteal  space.  I  Gas- 
trocnemius. 


762 


MUSCLES  OF  THE  LEG. 


FIG.  251. 


the  heads  of  the  gastrocnemii  to  the  external  condyle, 
which  has  been  called  the  posterior  ligament,  or  ligament 
of  Winslow. 

MUSCLES  OF  THE  LEG. 

Those  on  the  anterior  and  outer  leg.  Dissection. — Make 
an  incision  from  the  knee  joint  along  the  middle  of  the 
leg  between  the  tibia  and  fibula,  over 
the  ankle  joint  along  the  dorsum  of  the 
foot  to  the  toes.  Make  a  second  incision 
crossing  the  first  transversely  over  the 
ankle  joint.  Turn  aside  the  integument, 
and  then  the  fascia,  when  the  muscles 
will  be  exposed. 

The  tibialis  anticus  (Fig.  251)  arises 
fleshy  from  the  head  of  the  tibia,  the 
outer  edge  of  its  anterior  spine  for  about 
two-thirds  of  its  length,  the  interos- 
seous  ligament  and  fascia  of  the  leg. 
A  large  fleshy  muscle  is  formed,  which 
ends  in  a  strong  tendon  that  passes 
through  a  distinct  ring  of  the  annular 
ligament,  in  front  of  the  malleolus  inter- 
nus,  goes  to  be  inserted  into  the  base  of 
the  internal  cuneiform  bone  at  the  inner 
side  of  the  foot,  and  also  into  the  adjoin- 
ing base  of  the  metatarsal  bone  of  the 
great  toe.  A  bursa  is  seen  beneath  the 
tendon,  where  it  goes  through  the  annu- 
lar ligament.  Function. — To  flex  the 
foot  and  turn  it  obliquely  inward. 

The  extensor  communis  digitorum  pedis  (Fig.  25Y)  arises 
fleshy  and  tendinous  from  the  outer  head  of  the  tibia,  from 

FIG.  251  represents  the  Muscles  on  the  front  of  the  Leg.  1  Quadriceps 
femoris  tendon.  2  Spine  of  the  tibia.  3  Tibialis  anticus.  4  Extensor  com- 
munis digitorum.  5  Extensor  proprius  pollicis.  6  Peroneus  tertius.  7  Pero- 
neus  longus.  8  Peroneus  brevis.  9  9  Edges  of  the  soleus.  10  Gastrocnemius. 
11  .Extensor  brevis  digitorum. 


MUSCLES   OF  THE  LEG.  *763 

the  head  of  the  fibula  and  upper  three-fourths  of  this  bone ; 
also  from  the  interosseous  ligament,  intermuscular  septa, 
and  fascia  of  the  leg.  Its  fibres  descend  obliquely  inward, 
and  about  the  middle  of  the  leg  it  divides  into  four  ten- 
dons, which  pass  through  a  common  ring  under  the  annular 
ligament,  and  then  diverge,  expanding  over  the  back  of 
all  the  toes,  except  the  great  toe,  to  be  attached  to  the 
last  phalanx  of  each.  A  bursa  is  connected  with  these 
tendons  at  the  annular  ligament.  Function. — To  extend 
the  toes  and  flex  the  foot. 

The  extensor  proprius  pollicis  (Fig.  251)  arises  tendinous 
and  fleshy  from  the  middle  third  of  the  fibula,  and  from  the 
interosseous  ligament  nearly  as  low  as  the  ankle.  Its  fibres 
descend  obliquely  forward  to  a  tendon  which  passes  under 
the  annular  ligament  to  be  inserted  into  the  base  of  the 
first  and  second  phalanx  of  the  great  toe.  A  bursa  is  seen 
with  the  tendon  at  the  annular  ligament.  Function. — To 
extend  the  great  toe. 

The  peroneus  longus  (Fig.  251)  arises  around  the  head  of 
the  fibula,  tendinous  and  fleshy,  from  the  two  upper  thirds 
of  the  external  angle  of  the  fibula,  and  from  the  fascia  and 
intermuscular  septa.  Its  fibres  pass  obliquely  outward  to 
a  flat  tendon,  which  goes  behind  the  external  malleolus 
through  a  ligamentous  noose  provided  with  a  bursa,  and 
thence  proceeds  to  the  outer  side  of  the  os  calcis,  and  through 
a  groove  in  the  cuboides  where  it  meets  with  another  bursa, 
and  is  now  traced  deep  in  the  sole  of  the  foot  next  to  the 
tarsal  bones,  inward  and  forward,  to  be  inserted  into  the 
internal  cuneiform  and  base  of  the  metatarsal  bone  of  the 
great  toe.  Function. — To  extend  the  foot  and  turn  it  ob- 
liquely outward. 

The  peroneus  brevis  (Fig.  251)  arises  fleshy  and  tendinous 
from  the  outer  surface  of  the  lower  two-thirds  of  the  fibula. 
It  ends  in  a  tendon  which  passes  behind  the  external  mal- 
leolus in  the  same  groove  with,  and  concealed  by  the  pero- 
neus longus,  and  goes  to  be  inserted  into  the  os  cuboides 
and  base  of  the  metatarsal  bone  of  the  little  toe.  Func- 
tion.— The  same  as  the  last. 


764 


MUSCLES  OF  THE  LEG. 


[Fie.  252. 


The  peroneus  tertius  (Fig.  251)  forms  a  portion  of  the 
extensor  longus,  and  goes  to  the  base  of  the  metatarsal 
bone  of  the  little  toe.  Function.  —  To  flex  the  foot. 

MUSCLES   ON   THE   BACK   OF   THE   LEG. 

Dissection.  —  Make  an  incision  down  the  middle  back  part 
of  the  leg  from  the  knee  to  the  heel,  cross  this  at  its  centre 
by  a  transverse  incision,  then  turn  off  the  integument  and 
fascia,  when  the  muscles  will  be  exposed. 

Gastrocnemius  —  ya<^P,  the  belly;  xvqw, 
the  leg  —  (Fig.  252)  arises  by  two  heads  ; 
one  tendinous  and  fleshy,  from  the  ex- 
ternal condyle  and  ridge  leading  to  it; 
the  other  head  has  a  like  origin  from 
the  internal  condyle  and  its  ridge.     The 
two  heads  have  the  popliteal  vessels  pass- 
ing between  them.     They  unite  a  little 
below  the  knee  and  about  the  middle  of 
the  leg  form  a  broad  flat  tendon  to  unite 
with  the  soleus  or  gastrocnemius  internus, 
which  arises  fleshy  from  the  head  and 
upper  third  of  the  fibula,  from  the  up- 
per posterior  surface  of  the  tibia,  below 
the  popliteus,  and  from  the  internal  an- 
gle of  the  tibia  for  four  or  five  inches. 
A  large  fleshy  belly  is  formed,  constitu- 
ting the  calf  of  the  leg,  which  ends  in 
a  tendon  to  unite  with  that  of  the  gas- 
trocnemius externus.     The  union  of  the 
two  forms  the  tendo-Achillis  ,  which  goes 
to  be  inserted  into  the  posterior  part  of 
the  os  calcis.    A  bursa  is  found  between 
this  tendon  and  the  bone.    Function.  —  To  extend  the  foot. 

FIG.  252  represents  the  Superficial  Muscles  on  the  back  of  the  Leg.  a  Ten- 
don of  the  biceps,  b  Tendons  of  the  inner  hamstring  muscles,  c  Popliteal 
space,  d  Gastrocnemius.  e  Soleus.  /  Tendo-Achillis.  g  Its  insertion  into 
the  calcis.  h  Peroneus  longus  and  brevis  tendons,  i  Tendons  of  the  fiexor- 
longus-digitorum,  and  tibialis  posticus. 


MUSCLES  OP  THE  LEG. 


T65 


The  plantaris  arises  fleshy  from  the  ridge  leading  to  the 
external  condyle,  forms  a  short  fleshy  belly  hid  by  the 
gastrocnemius,  which  passes  across  and  adheres  to  the 
capsular  ligament  of  the  joint.  It  ends  in  a  long,  flat, 
delicate  tendon  which  emerges  between  the  gastrocnemius 
and  soleus,  and  then  descends  along  the  inner  edge  of  the 
tendo-Achillis  to  be  inserted  into  the  posterior  and  inner 
part  of  the  os  calcis.  Function. — To  extend  the  foot.  This 
muscle  is  sometimes  absent. 

The  popliteus  arises  by  a  round  tendon  on  the  outer  face 
of  the  external  condyle,  behind  the  knee-joint,       FIG.  253. 
and  forms  a  fleshy  belly,  which  descends  in- 
ward to  be  inserted  into  the  ridge  below  the 
head  of  the  tibia.     A  bursa  is  seen  between 
its  tendon  and  the  capsular  ligament. 
'.._  Function. — To  flex  the  leg  and  turn  it  in- 
ward. 

The  flexor  longus  or  communis  digitorum 
pedis  (Fig.  253)  arises  from  the  posterior 
part  of  the  tibia,  below  the  popliteus,  and 
from  the  angle  of  the  tibia,  nearly  to  the 
ankle  joint.  It  ends  in  a  tendon  which  runs 
in  a  groove  behind  the  internal  malleolus, 
being  confined  here  by  a  strong  ligamentous 
band;  it  then  passes  along  the  sinuosity  of 
the  os  calcis  to  the  sole  of  the  foot,  receiving 
at  this  point  an  accessory  tendon  from  the 
flexor  longus  pollicis.  It  divides  into  four 
tendons  which  pass  through  slits  in  the  flexor 
brevis,  and  are  inserted  into  the  base  of  the 
third  phalanx  of  the  smaller  toes.  This  mus- 

FIG.  253  represents  the  deep  Muscles  on  the  back  of  the  Leg.  ]  Lower 
portion  of  the  femur.  2  Ligament  of  Winslow.  3  Tendon  of  semi-membra- 
nosus.  4  Internal  lateral  ligament  of  the  knee-joint.  5  External  lateral 
ligament  of  the  same  joint.  6  Popliteus  muscle.  7  Flexor  longus  digitorum 
pedis.  8  Tibialis  posticus.  9  Flexor  longus  pollicis.  10  Peroneus  longus. 
11  Peroneus  brevis.  12  Insertion  of  tendo-Achillis.  13  Tendons  of  flexor 
longus  and  tibialis  posticus. 


"766  MUSCLES  OF  THE  FOOT. 

cle  is  consequently  a  perforans.  A  bursa  is  found  with 
this  tendon  at  the  os  calcis  and  sole  of  the  foot. 

Function. — To  bend  the  smaller  toes  and  extend  the  foot. 

The  flexor  longus  polUcis  (Fig.  253)  arises  tendinous  and 
fleshy  from  the  posterior  surface  of  the  lower  two-thirds 
of  the  fibula.  It  ends  in  a  tendon  which  goes  through  a 
groove  in  the  back  part  of  the  tibia^and  astragalus,  con- 
nects with  the  flexor  longus  digitorum,  and  goes  to  be 
inserted  into  the  last  phalanx  of  the  great  toe. 

Function. — To  bend  the  great  toe  and  extend  the  foot. 

A  bursa  is  seen  in  connection  with  the  tendon  at  the 
astragalus,  os  calcis,  metatarsal  bone  and  phalanx. 

The  tibialis  posticus  (Fig.  253)  arises  from  the  front  of 
the  tibia  where  it  connects  with  the  fibula,  and  gets  through 
the  interosseous  ligament,  arising  from  this  latter  almost 
its  whole  length,  as  well  as  from  the  fibula  and  tibia  adja- 
cent to  the  ligament.  It  ends  in  a  tendon  which  passes 
behind  the  internal  malleolus  forward  and  inward,  to  be 
inserted  into  the  naviculare,  internal  cuneiform,  cuboid, 
and  second  and  third  metatarsal  bones.  At  its  insertion  a 
small  sesamoid  bone  and  bursa  are  seen.  Function. — To 
extend  the  foot  and  turn  it  obliquely  inward. 

MUSCLES   OF  THE  FOOT. 

Dissection. — Make  an  incision  from  the  heel,  along  the 
inner  and  outer  margins  of  the  foot ;  turn  down  the  integu- 
ment, and  then  the  thick  adipose  layer  to  the  plantar  apon- 
eurosis.  The  latter  being  removed,  the  muscles  are  exposed. 

The  muscles  on  the  sole  of  the  foot  are  divided  into  four 
layers. 

FIRST  LAYER. 

The  abductor  pollicis  pedis  arises,  tendinous  and  fleshy, 
from  the  internal  and  lower  part  of  the  os  calcis,  and  from 
the  annular  ligament,  and  plantar  aponeurosis.  Its  fibres 
run  along  the  inner  side  of  the  foot,  and  are  inserted  into 
the  base  of  the  first  phalanx  of  the  great  toe  and  the  inner 
sesamoid  bone.  Function. — To  draw  the  great  toe  from 
the  others. 


MUSCLES  OF  THE  FOOT. 


T6T 


The  abductor  minimi  digiti  pedis  (Fig.  254)  arises  tendi- 
nous arid  fleshy  from  the  outer  side  of  the  os  calcis,  the 
plantar  fascia,  and  the  base  of  the  me-  FIG.  254. 

tatarsal  bone  of  the  little  toe,  and  is 
inserted  tendinous  into  the  outer  part 
of  the  base  of  the  first  phalanx  of  the 
Kttle  toe,  running  along  the  outer 
margin  of  the  foot. 

Function.— -To    draw  the   little  toe 
from  the  rest. 

The  flexor  brevis  digitorum  pedis 
(Fig.  254)  arises  fleshy  from  the  lower 
surface  of  the  os-calcis,  from  the  plan- 
tar aponeurosis,  and  the  intermuscular 
septa.  It  forms  a  fleshy  mass,  situated 
between  the  two  former  muscles,  and 
about  the  middle  of  the  metatarsal 
bones  it  divides  into  four  tendons, 
each  of  which  has  a  slit  for  the  pas- 
sage of  the  flexor  longus,  and  is  inserted  into  the  base 
of  one  of  the  second  phalanges  of  the  smaller  toes.  This 
muscle  is  hence  a  perforatus. 

Function. — To  flex  the  second  joint  of  the  toes. 

SECOND   LAYER. 

The  flexor  accessorius,  or  massa  carnea  Jacobi  Sylvii,  (Fig. 
255,)  arises  fleshy  and  tendinous  from  the  lower  and  inner 
part  of  the  os  calcis,  and  is  inserted  into  the  outer  side  of 
the  tendon  of  the  flexor  longus  just  as  it  is  dividing  into 
its  four  tendons.  Function. — To  flex  the  toes. 

The  lumbricales  pedis  (Fig.  255)  arise  by  four  tendinous 
and  fleshy  slips  (consist  in  fact  of  four  small  muscles)  from 
the  tendon  of  the  flexor  longus  digitorum,  and  are  inserted 

Fi«.  254  represents  the  first  layer  of  Muscles  on  the  sole  of  the  Foot, 
a  Abductor  pollicis  pedis.  6  6  Its  tendon,  c  c  Flexor  brevis  pollicis  pedis. 
d  Tendon  of  flexor  longus  pollicis.  e  Aponeurosis  plantaris.  /  Flexor  brevis 
digitorum  pedis.  g  Lumbricales.  h  Abductor  minimi  digiti  pedis.  i  Flexor 
brevis  minimi  digiti.  j  Interosseii. 


768 


MUSCLES  OF  THE  FOOT. 


into  the  base  of  the  smaller  toes  at  the  first  phalanx  and 
expansion  of  the  extensor  tendons. 


FIG.  255. 


THIRD   LAYER. 

The  flexor  Irevis  pollicis  (Fig.  255)  arises  by  two  heads, 
between  which  the  tendon  of  the  long  flexor  passes,  from 
the  lower  surface  of  the  os  calcis  and 
external  cuneiform  bone.  It  forms  a 
fleshy  belly,  connected  with  the  abduc- 
tor and  adductor  pollicis,  and  is  inserted 
into  the  two  sesamoid  bones  at  the  first 
phalanx  of  the  great  toe. 

Function. — To  flex  the  first  joint  of 
the  great  toe. 

The  adductor  pollicis  (Fig,  255) 
arises,  tendinous  and  fleshy,  on  the 
outside  of  the  ]ast,  from  the  calcaneo- 
cuboid  ligament,  and  base  of  the  second 
and  third  metatarsal  bones,  and  is  in- 
serted into  the  external  sesamoid  and 
base  of  the  first  phalanx  of  the  great 
toe.  Function. — To  bring  the  great 
toe  towards  the  rest. 

The  transversalis  pedis  arises  from 
the  heads  of  the  four  lesser  metatarsal  bones  by  fleshy  slips, 
which  running  transversely  are  inserted  into  the  base  of 
the  first  phalanx  of  the  great  toe.  Function. — To  approxi- 
mate the  toes. 

The  flexor  brevis  minimi  digiti  (Fig.  255)  arises  tendinous 
and  fleshy  from  the  cuboid  and  base  of  the  fifth  metatarsal 
bone,  and  is  inserted  into  the  base  of  the  first  phalanx  of 
the  little  toe.  Function. — To  flex  the  little  toe. 

FIG.  255  represents  the  second,  third  and  fourth  layers  of  muscles  on  the  sole 
of  the  foot,  a  Tendon  of  tibialis  posticus.  b  Tendon  of  flexor  longus  pollicis. 
c  Tendon  of  flexor  longus  digitorum.  d  Division  of  the  latter  into  four  tendons. 
e  Their  points  of  insertion.  /Flexor  accessorius.  g  Calcaneo  cuboid  ligament. 
h  Lumbricales  pedis.  i  Abductor  pollicis.  j  Flexor  brevis  pollicis.  k  Tendon 
of  peroneus  longus.  I  Flexor  brevis  minimi  digiti.  m  Interossei. 


MUSCLES   OF  THE  FOOT. 


769 


FOURTH  LAYER. 

The  interossei  plantares  (Fig.  255)  are  three  in  number, 
and  occupy  the  interosseal  spaces.  They  arise  from  the 
base  of  the  metatarsal  bones,  corresponding  to  the  three 
outer  toes,  and  are  inserted  into  the  base  of  the  first  pha- 
lanx of  these  toes  at  their  inner  side.  Function. — To  ad- 
duct  the  toes. 

MUSCLES   ON  THE  DORSUM  OF  THE  FOOT. 

The  extensor  brevis  digitorum  pedis  (Fig.  256)  arises  ten- 
dinous and  fleshy  from  the  anterior  and  outer  part  of  the 
os  calcis,  crosses  the  foot  obliquely,  and  FIG.  256. 

divides  into  four  delicate  tendons.  The 
most  internal  is  inserted  into  the  base 
of  the  first  phalanx  of  the  great  toe ; 
the  other  three  join  the  tendons  of  the 
extensor  longus,  which  expand  on  the 
back  of  the  other  toes.  Function. — To 
extend  the  toes. 

The  interossei  dorsales  (Fig.  256)  are 
four  in  number,  on  the  back  of  the  foot, 
and  resemble  those  on  the  hand  in  aris- 
ing by  two  heads  from  adjacent  sides  of 
the  metatarsal  bones.  The  first  is  in- 
serted on  the  inner  side  of  the  first  pha- 
lanx of  the  second  toe,  and  is  an  adduc- 
tor. The  other  three  are  inserted  on 
the  outer  side  of  the  second,  third,  and  fourth  toes,  and 
are  abductors. 

SECTION    II. 
FASCIA  OF  THE  INFERIOR  EXTREMITY. 

The  fasciae  of  the  thigh  are  divided  into  the  superficial 
fascia  and/ascia  lata. 

FIG.  256  represents  the  muscles  on  the  Dorsum  of  the  Foot,  a  6  c  Extensor 
brevis  digitorum  pedis.  d  Occasional  supernumerary  tendon,  t  Section  of 
tendons  of  Extensor  communis.  /  Section  of  tendon  of  Extensor  proprius  pol- 
licis.  g  Interossei  muscles,  h  Superior  astragalo  scaphoid  ligament. 

49 


770  FASCIA  OP  THE  INFERIOR  EXTREMITY. 

The  superficial  is  a  continuation  of  the  same  loose  mem- 
brane covering  the  abdomen.  As  it  passes  over  Poupart's 
ligament,  it  becomes  more  closely  connected  with  the  deep 
layer.  Upon  the  thigh  it  can  be  separated  into  two  layers, 
enclosing  the  lymphatic  glands  of  the  groin,  adipose  matter, 
and  superficial  vessels  and  nerves.  It  can  be  traced  inward 
to  the  symphysis  pubis,  and  backward  over  the  gluteal 
muscles.  In  the  groin  it  has  a  close  connection  with  the 
fascia-lata. 

The/ascta  lata  or  femoral  aponeurosis  completely  invests 
the  thigh,  not  only  surrounding  all  its  muscles,  but  sending 
partitions  within  so  as  to  form  separate  sheaths  for  each. 

It  extends  from  the  pelvis  above,  where  it  is  continuous 
with  the  iliac  and  perineal  fascia,  to  the  knee  below,  where 
it  is  traced  into  the  fascia  of  the  leg. 

Above  it  is  connected  anteriorly  and  externally  to  Pou- 
part's ligament  and  the  crest  of  the  ilium,  internally  to 
the  raini  of  the  pubis  and  ischiuin,  and  posteriorly  to  the 
sacrum  and  coccyx ;  below  it  surrounds  the  knee-joint,  and 
is  attached  to  the  condyles.  This  fascia  is  very  strong,  but 
varies  in  strength  and  density  at  different  points.  On  the 
gluteus  maximus  it  is  thin  and  weak ;  on  the  gluteus 
medius  it  is  very  thick  and  strong ;  on  the  outer  side  of 
the  thigh  it  is  much  thicker  and  stronger  than  on  the 
inner.  It  has  been  stated  that  the  fascia  lata  surrounds 
and  forms  separate  sheaths  for  the  muscles  by  the  various 
processes  it  sends  off.  It  is  connected  to  the  linea-aspera, 
and  by  its  processes  affords  attachment  to  several  muscles. 
It  presents  many  foramina  on  its  surface,  which  give  pas- 
sage to  vessels  and  nerves.  One  large  opening  is  especially 
noticed  in  it,  about  two  inches  below  Poupart's  ligament, 
for  the  internal  saphena  vein. 

This  saphenic  opening  becomes  the  dividing  point  of  the 
fascia  lata  into  two  portions.  All  on  its  outside  being  called 
the  iliac,  and  all  on  its  inside  the  pubic  portion  of  the  fascia 
lata.  The  iliac  portion  is  attached  to  Poupart's  ligament, 
and  goes  in  front  of  the  femoral  vessels  in  the  form  of  a 
crescent,  and  is  hence  called  the  crescentic  or  falciform  pro- 


FASCIA  OF   THE  INFERIOR  EXTREMITY. 

cess.  The  pubic  portion  is  connected  to  the  spine  and  linea 
innominata  of  the  pubis,  goes  behind  the  femoral  vessels, 
and  is  continuous  with  the  fascia  iliaca.  Between  and 
connected  to  the  margins  of  the  falciform,  pubic,  and  iliac 
portions  of  the  fascia  lata,  a  thin  membrane,  having  many 
foramina  for  the  passage  of  vessels,  is  seen,  called  cribri- 
form fascia.  The  fascia  lata  is  distinctly  double  at  some 
points,  as  for  instance  where  it  receives  the  insertion  of  the 
tensor  vaginae  femoris  muscle  between  its  two  layers. 

The  fascia  of  the  leg  is  continuous,  as  stated,  with  the 
fascia  lata.  It  is  strongly  attached  to  the  head  of  the  tibia 
and  fibula,  to  the  spine  of  the  tibia,  to  the  external  and 
internal  malleolus,  and  at  the  ankle-joint  thickens,  to  form 
the  annular  ligaments.  It  also  surrounds,  and  at  its  upper 
portion  sends  processes  between  the  muscles,  called  inter- 
muscular  septa.  On  the  anterior  leg  it  is  thicker  than 
behind,  and  in  front  of  the  ankle  joint  it  forms  the  anterior 
annular  ligament,  which  is  about  an  inch  and  a  half  broad. 
It  is  attached  to  the  os  calcis  on  its  outer  side;  whence  it 
spreads  forward,  and  to  the  inner  side,  where  it  presents 
two  bands,  one  going  to  the  internal  malleolus,  the  other 
to  the  naviculare,  and  the  plantar  fascia.  The  extensor 
tendons  pass  beneath  this  ligament,  having  distinct  sheaths 
with  bursa3.  Posteriorly  the  fascia  is  thinner  and  double. 
Its  strength  is  however  increased  by  fibres  from  the  ham- 
string tendons.  Its  superficial  layer  is  immediately  beneath 
the  skin.  Its  deep  layer  is  situated  between  the  tibia  and 
fibula,  and  is  called  the  intermuscular  fascia.  At  the  ankle 
joint  the  posterior  fascia  of  the  leg,  its  superficial  portion, 
becomes  thickened  to  form  the  external  and  internal  annular 
ligaments.  The  former  stretches  from  the  outer  malleolus 
to  the  os-calcis,  and  binds  down  the  peroneal  tendons ;  the 
latter  goes  from  the  internal  malleolus,  to  the  tuberosity 
and  side  of  the  calcis.  This  is  a  strong  ligament  and  gives 
passage  and  protection  to  the  flexor  tendons  and  vessels. 

The/a,sc^a  upon  the  dorsum  of  the  foot  is  continued  from 
the  anterior  annular  ligament,  and  forms  only  a  thin  layer. 

The  plantar  fascia  (aponeurosis  plantaris)  is  a  very  thick. 


772  ARTERIES  OF  THE  INFERIOR  EXTREMITY. 

dense,  fibrous  membrane,  situated  between  the  skin  and 
muscles,  attached  to  the  tubercles  of  the  os  calcis,  and 
spreading  over  the  whole  sole  of  the  foot.  It  is  divided 
into  three  portions, — an  outer,  attached  to  the  base  of  the 
fifth  metatarsal  bone — an  inner  connected  to  the  metatar- 
sus of  the  great  toe;  and  a  middle,  much  thicker  and 
denser,  which,  as  it  leaves  the  os  calcis,  expands,  and,  at 
the  heads  of  the  metatarsal  bones,  divides  into  five  fasciculi, 
each  of  which  again  divides  so  as  to  form  a  slit  for  the 
passage  of  the  flexor  tendons.  These  go  to  be  inserted  into 
the  sides  of  the  basis  of  the  first  phalanges  of  the  toes. 

SECTION   III. 
BLOOD-VESSELS  OF  THE  INFERIOR  EXTREMITY. 

The  femoral  and  popliteal  arteries,  with  their  branches, 
,are  the  sources  of  arterial  supply  to  the  lower  extremity. 

FEMORAL   ARTERY. 

'The  femoral  artery  is  a  continuation  of  the  external  iliac. 
At  about  the  centre  of  Poupart's  ligament  it  commences, 
and  extends  obliquely  inward  along  the  anterior  thigh  to 
an  opening  in  the  adductor  magnus  muscle,  through  which 
it  passes,  and  changes  its  name  to  popliteal. 

In  its  course  it  first  passes  over  the  common  junction  of 
the  psoas  magnus  and  iliacus  internus,  then  over  the  ad- 
ductors brevis  and  longus.  Above  it  is  rather  superficial 
and  simply  covered  by  a  thin  layer  of  the  fascia  lata ;  at 
the  middle  of  the  thigh  the  sartorius  crosses  it,  and  here  is 
also  seen  a  strong  covering  of  aponeurotic  membrane  from 
the  vastus  internus,  and  adductor  longus.  At  Poupart's 
ligament  the  femoral  vein  is  on  the  inside  of  the  artery, 
while  as  it  descends  the  vein  gets  behind  it.  The  anterior 
crural  nerve  is  to  the  outside,  and  one  of  the  branches  de- 
scends along  the  front  of  the  artery  within  the  sheath. 

A  line  drawn  from  midway  between  the  anterior  supe- 
rior spinous  process  of  the  ilium  and  symphysis  pubis  to 
the  inner  sido  of  the  patella,  will  indicate  the  course  of  this 
vessel. 


ARTERIES  OF  THE  INFERIOR  EXTREMITY. 


FIG.  257. 


BRANCHES  OF  THE  FEMORAL  ARTERY,    (Fig. 

The  superficial  epigastric  comes  from  the  femoral,  just 
below  Poupart's  ligament,  pierces  the  fascia-lata,  and  as- 
cends to  the  umbilicus,  immediately 
beneath  the  skin,  giving  branches  to 
the  inguinal  glands. 

The  superficial  circumfiexa  ilii  comes 
also  from  the  femoral,  just  below 
Poupart's  ligament,  goes  through  the 
fascia,  and  proceeds  outward  to  the 
crest  of  the  ilium,  giving  branches 
to  the  glands  of  the  groin,  the  super- 
ficial  fascia,  and  the  skin. 

The  external  pudic,  two  or  three  in 
number,  small,  and  sometimes  coming 
from  a  common  trunk,  are  distributed 
upon  the  inguinal  glands,  penis,  scro- 
tum of  the  male,  and  labia  of  the 
female. 

The  prof  unda  femoris  is  the  largest 
branch,  and  comes  from  the  femoral 
about  two  inches  below  Poupart's  liga- 
ment. It  descends  behind  the  femoral, 
and  gives  off  the  following  branches : 

The  external  circumflex,  which  sometimes  comes  from  the 
femoral,  passes  behind  the  sartorius  and  rectus  muscles  to 
the  outer  side  of  the  thigh,  where  it  divides  into  three  sets 
of  branches,  a  superior  and  middle,  supplying  the  tensor 
vaginre,  gluteus  medius,  and  anastomosing  with  the  glu- 
teal,  ischiatic,  and  internal  circumflex  arteries ;  and  a  de- 
scending set,  which  go  to  the  knee  and  anastomose  with 
the  external  articular. 

FIG.  257  represents  the  Femoral  Artery  with  its  branches,  a  to  6  Femoral 
artery,  c  Superficial  epigastric,  d  d  External  pudics.  t  e  Profunda  femoris. 
/  Internal  circumflex,  g  External  circumflex,  h  h  Perforating  arteries,  i 
Epigastric,  j  Circumflexa  ilii.  k  Muscular  branches.  I  Superior  internal 
articular,  m  Branch  of  the  latter. 


ARTERIES  OF  THE  INFERIOR  EXTREMITY. 

The  internal  circumflex,  larger  than  the  last,  comes  off 
"below  it,  and  sometimes  from  it.     It  passes  deep  between 
the  psoas  and  pectineus  muscles,  and  winds  round  the  neck 
of  the  femur,  supplying  the  hip  joint  and  rotator  muscles. 
The  perforating  arteries  are  three  or  four  in  number, 
and  named  numerically  first,  second,  third,  and  fourth. 
FIG.  258.        They  perforate  the  adductor  magnus,  and 
are  distributed  to  the  muscles  on  the  back 
of  the  thigh. 

The  anastomotica  magna  is  the  last  branch 
of  the  femoral  just  at  its  termination ;  it 
descends  to  supply  the  parts  about  the  knee, 
and  to  anastomose  with  the  articular  and 
long  branches  of  the  external  circumflex. 

Muscular  brandies  are  given  off  by  the 
femoral  through  all  its  course. 

THE  POPLITEAL  ARTERY. 

The  popliteal  artery  extends  from  the 
opening  in  the  tendon  of  the  adductor 
magnus,  to  the  opening  in  the  interosseous 
ligament  of  the  leg,  and  is  a  continuation 
of  the  femoral.  Its  course  is  obliquely  out- 
ward to  the  centre  and  lower  part  of  the 
popliteal  space,  situated  between  the  outer 
and  inner  hamstring  muscles,  and  imbedded 
in  a  quantity  of  adipose  matter.  Both  the 
popliteal  vein  and  nerve  are  superficial  to 
the  artery. 

FIG.  258  represents  the  Popliteal  and  Posterior  Tibial  Artery.  1  Tendons 
forming  the  inner  hamstring.  2  Tendon  of  outer  hamstring.  3  Popliteus 
muscle.  4  Flexor  longus  digitorum.  5  Tibialis  posticus.  6.  Fibula.  7 
Peroneii  muscles.  8  Flexor  longus  pollicis.  9  Popliteal  artery,  which  is 
seen  to  give  off  at  its  upper  part  two  superior  articular  branches,  the  one 
external,  the  other  internal ;  also  two  at  its  lower  part,  called  inferior  external 
and  internal  articular  branches,  with  one  in  the  centre— the  middle  articular. 
10  Anterior  tibial  artery.  11  Posterior  tibial  artery.  12  Relation  of  artery 
with  tendons  at  the  ankle  joint.  13  Peroneal  artery.  14  Posterior  peroneal 
branch. 


ARTERIES  OF  THE  INFERIOR  EXTREMITY. 


FIG.  259. 


BRANCHES  OF  THE  POPLITEAL  ARTERY,    (Fig.  258.) 

Muscular  branches  supplying  the  hamstring  and  gastroc- 
nemius. 

The  superior  articular,  external  and 
internal,  wind  round  the  condyles  of 
the  femur,  supply  the  knee  joint,  and 
anastomose  with  the  lower  articular, 
the  anastomotica,  and  the  external  cir- 
cumflex arteries. 

The  inferior  articular  surround  the 
lower  part  of  the  knee  joint  about  the 
head  of  the  tibia,  and  are  also  external 
and  internal.  They  anastomose  with  the 
superior  and  anterior  tihial  recurrent. 

The  middle  articular  or  azygos  is  the 
smallest  of  the  articular  hranches,  and 
pierces  the  posterior  ligament  to  supply 
the  synovial  memhrane  of  the  joint. 

The  sural  or  gastrocnemial  branches, 
two  in  number,  go  to  the  heads  of  the 
gastrocnemius.  At  the  lower  border  of 
the  popliteal  space  the  popliteal  artery 
divides  into  the  anterior  and  posterior 
tibial  arteries. 

ANTERIOR  TIBIAL  ARTERY. 

The  anterior  tibial  passes  through 
the  opening  of  the  interosseous  liga- 

FIG.  259  represents  the  anterior  Tibial  artery  and  Nerves  of  the  Leg. 
1  Patella.  2  Tendon  of  rectus  muscle.  3  Vastus  externus.  23  External 
cutaneous  nerve.  24  Superior  external  articular  artery.  4  Vastus  internus 
mnscle.  25  Superior  internal  articular  artery.  5  Patellar  branches  of  the 
saphenous  nerve.  6  Inferior  internal  articular  artery.  7  Inferior  external 
articular  artery.  8  Recurrent  articular.  26  Tibialis  anticus  muscle.  9  9  An- 
terior tibial  artery.  27  Anterior  tibial  nerve.  28  Extensor  longus  digitorum. 

29  Anterior  annular   ligament.      11    Extensor  proprius   pollicis.     12  Tibia. 

30  Internal  saphenous  vein.    31   Saphenous   nerve.     13   Internal   malleolar 
artery.     14  External  malleolar  artery.     15  Anterior  peroneal  artery.     16  Ex- 
ternal popliteal  nerve.    17  17  Cutaneous  branches  of  external  popliteal  nerve. 
32  Gastrocnemius  muscle.     18  Musculo-cutaneous  nerve.     19  19  Venous  arch 
on  the  dorsum  of  the  foot.    20  Dorsalis  pedis  artery.    22  Tarsal  artery. 


ARTERIES  OF   THE   INFERIOR   EXTREMITY. 

ment,  near  the  head  of  the  fibula,  and  descends  in  front  of 
the  ligament,  being  deeply  hid  above  by  the  tibialis  anticus 
and  extensor  longus.  At  its  lower  part  it  is  superficial, 
passing  under  the  annular  ligament  and  over  the  front  of 
the  ankle  joint,  where  it  can  be  felt  pulsating,  and  runs  to 
the  base  of  the  metatarsal  bone  of  the  great  toe  where  it 
terminates.  Two  veins  and  the  anterior  tibial  nerve  ac- 
company this  artery. 

BRANCHES  OF  THE  ANTERIOR  TIBIAL  ARTERY. 

The  recurrent  passes  inward  and  upward  around  the 
knee  joint,  and  anastomoses  with  the  articular. 

Muscular  branches  are  given  oif  all  along  the  course  of 
the  artery  to  the  muscles. 

The  malleolar,  external  and  internal,  go  to  the  outer  and 
inner  side  of  the  ankle  joint. 

The  tarsal  supply  the  tarsus. 

The  metatarsal  gives  branches  to  the  tarsus,  and  supplies 
three  of  the  outer  interosseal  spaces. 

The  arteria  pollicis  is  the  continued  trunk  of  the  ante- 
rior tibial,  which  runs  along  the  back  of  the  great  toe,  and 
sends  a  branch  to  the  adjoining  toe. 

The  communicans  is  another  terminating  branch  of  the 
anterior  tibial,  which  descends  between  the  two  heads  of 
the  first  dorsal  interosseous  muscle  into  the  sole  of  the  foot 
to  anastomose  with  the  external  plantar  artery. 

The  posterior  tibial  artery  (Fig.  258)  forms  the  other  ter- 
minating branch  of  the  popliteal,  and  extends  from  the 
head  of  the  tibia  to  the  sinuosity  of  the  os  calcis.  It 
descends  the  posterior  part  of  the  leg,  covered  by  the  gas- 
trocnemius  and  soleus,  and  at  its  lower  portion  runs  along 
the  inner  margin  of  the  tendo-Achillis  behind  the  malleolus 
internus.  The  posterior  tibial  nerve  and  two  veins  attend  it. 

BRANCHES  OF  THE  POSTERIOR  TIBIAL  ARTERY. 

The  peroneal  artery  is  the  first  branch  of  importance, 
and  descends  along  the  inner  border  of  the  fibula  to  the 
external  ankle,  supplying  branches  to  the  muscles  in  its 


ARTERIES  OF   THE  INFERIOR   EXTREMITY. 


course,  and  dividing  into  the  anterior  bud.  posterior  peroneal 
arteries.     The  former  gets  through  the  interosseous  liga- 
ment, about  two   inches   above   the  F,G>  260. 
ankle,  and  is  distributed  upon  the 
upper  external  part  of  the  foot ;  the 
latter  supplies  the  heel  and  external 
ankle.  Muscular  branches  are  given  off 
to  the  various  muscles  in  its  course. 

The  nutritious  artery  enters  the  nu- 
tritious foramen  of  the  tibia. 

The  plantar  arteries  form  the  ter- 
minating branches,  and  are  two  in 
number. 

The  external,  the  larger  of  the  plan- 
tar branches,  passes  outward  and  for- 
ward above  the  flexor  brevis  to  the 
fifth  metatarsal  bone;  from  this  it 
curves  inward,  across  the  foot,  to  the 
first  metatarsal  bone,  forming  the  ar- 
cus  plantarisj  and  ends  by  anastomo- 
sing with  the  anterior  tibial.  In  its  course  the  external 
plantar  gives  off  the  perforating  branches,  four  in  number, 
from  its  arch,  which  perforate  as  well  as  supply  the  inter- 
osseous  muscles. 

The  digital  arteries  come  also  from  the  plantar  arch,  and 
after  sending  branches  to  the  lumbricales  and  interossei, 
divide  so  as  to  supply  the  adjacent  sides  of  contiguous  toes. 
The  artery  of  the  little  toe  runs  along  its  outer  surface. 

The  internal  plantar  passes  along  the  inner  side  of  the 

FIG.  260  represents  the  Arteries  on  the  Sole  of  the  Foot,  o  Posterior  tibial 
artery.  6  Branches  to  the  heel,  c  Branch  of  the  posterior  peroneal  artery. 
d  Point  of  division  into  external  and  internal  plantar  arteries,  e  External 
plantar.  /Point  where  the  external  plantar  begins  to  form  its  arch,  g  Anas- 
tomosis of  anterior  tibial  with  the  plantar  arch,  h  i  j  Muscular  branches  of 
external  plantar,  k  Anastomosis  of  external  plantar  with  the  metatarsal  artery. 
I  m  Digital  branches  to  the  little  toe.  n  Digital  branches  to  the  other  toes, 
o  o  Distribution  of  latter  upon  the  toes,  p  Internal  plantar  artery,  q  Its  anas- 
tomosis with  the  plantar  arch,  r  s  t  Muscular  branches  of  internal  plantar. 
u  Digital  branch  to  the  big  toe.  v  Sub  articular  branch.  *  Anastomosis  in 
the  pulp  of  the  toe. 


778 


VEINS  OF  THE  INFERIOR  EXTREMITY. 


sole  of  the  foot,  supplying  the  muscles  of  the  great  toe,  and 
anastomosing  with  the  digital  arteries. 

VEINS   OF  THE   INFERIOR   EXTREMITY. 

FIG.  261.  The  veins  of  the  lower  extremity,  like 

those  of  the  upper,  are  divided  into  the 
superficial  and  deep.  The  superficial  veins 
are  situated  immediately  beneath  the  skin, 
and  consist  of  the  internal  and  external 
sapliena. 

The  internal  sapliena  begins  on  the  inner 
and  upper  part  of  the  foot,  ascends  in  front 
of  the  internal  malleolus,  along  the  inner 
portion  of  the  leg  to  the  inner  condyle, 
behind  which  it  passes  ;  from  this  it  still 
ascends  along  the  inner  and  anterior  part 
of  the  thigh  to  within  two  inches  of  Pou- 
part's  ligament,  where  it  penetrates  the 
fascia  lata  to  join  the  femoral  vein.  In 
this  course  it  receives  numerous  cutaneous 
veins,  and  at  its  termination  is  joined  by 
the  pudic,  superficial  epigastric,  and  su- 
perficial circumflex  veins. 

The  external  sapliena  begins  at  the  outer 
ankle  and  dor  sum  of  the  foot,  ascends  on 
the  back  of  the  leg  to  the  ham,  where  it 
joins  the  popliteal  vein. 

The  deep  veins  accompanying  the  arte- 
ries have  the  same  names,  and  are  two 
for  each  artery,  called  venae  comites; 
hence  we  have  anterior,  posterior  tibial  and  peroneal  veins, 
uniting  to  form  the  popliteal,  which  is  superficial  to  the 
artery.  After  traversing  the  popliteal  space  to  the  opening 
in  the  tendon  of  the  adductor  magnus,  it  changes  its  name 
to  femoral.  From  this  point  the  femoral,  which  is  here  on 

FIG.  261  represents  the  Saphena  Major  Vein,  a  Superficial  epigastric  vein, 
ft  Internal  pudic  vein,  c  Superficial  circumflex  vein,  d  Orfgin  of  saphena 
major,  e  Its  termination  in  the  femoral  vein. 


NERVES  OF  THE  INFERIOR  EXTREMITY. 

the  outside  of  the  artery,  gets  behind  it  as  it  ascends-,  and 
at  the  upper  part  of  the  thigh  is  on  the  inner  side.  Having 
reached  Poupart's  ligament,  it  again  changes  its  name,  and 
becomes  the  external  iliac  vein,  which  will  be  found  described 
along  with  the  veins  of  the  trunk.  The  popliteal  receives, 
besides  the  external  saphena,  the  articular  veins  of  the 
knee  joint.  The  femoral,  besides  the  internal  saphenus, 
receives  the  muscular  veins  and  veins  of  the  profunda. 

SECTION   IV. 

NERVES  OF  THE  INFERIOR  EXTREMITY. 

The  source  of  nervous  supply  to  the  lower  extremity 
comes  from  the  lumbar  and  sacral  plexuses.  These  plexuses 
(see  Fig.  204)  form  two  large  nerves,  the  anterior  crural, 
and  great  sciatic,  the  origin  of  which,  together  with  the 
plexuses,  are  all  described  under  the  head  of  nerves  of  the 
chest  and  abdomen.  The  branches  from  the  lumbar  plexus 
which  supply  the  upper  part  of  the  thigh,  as  the  nmsculo- 
cutaneous,  genito  crural,  obturator,  and  anterior  crural,  have 
also  been  described. 

BRANCHES  OF  THE  ANTERIOR  CRURAL  NERVE. 

The  cutaneous  branches,  four  or  five  in  number,  pierce  the 
fascia  lata,  and  from  their  direction  upon  the  skin,  have 
been  called  the  middle,  external,  internal  and  anterior  cuta- 
neous nerves.  These  principally  supply  the  integuments 
on  the  anterior  and  inner  part  of  the  thigh,  some  descend- 
ing as  low  as  the  knee. 

Muscular  Brandies. — These  are  numerous  to  the  various 
muscles  on  the  front,  inner  and  outer  portions  of  the  upper 
part  of  the  thigh. 

The  arterial  branch  penetrates  the  sheath  of  the  femoral 
vessels,  and  sends  twigs  which  surround  them. 

The  internal  saphenus  penetrates  the  sheath  and  accom- 
panies the  femoral  artery  to  the  opening  in  the  adductor 
magnus.  It  here  leaves  the  artery,  and  getting  to  the  inner 
side  of  the  knee,  between  the  tendons  of  the  sartorius  and 
gracilis,  joins  the  internal  saphena  vein,  which  it  attends. 


NERVES  OF  THE  INFERIOR  EXTREMITY. 

to  the  inner  side  of  the  foot,  supplying  in  its  course  the 
integuments  of  the  leg.     The  internal  saphenus  communi- 
cates with  the  obturator,  and  the  following  branches  are 
FIG.  262.  named  as  proceeding  from  it :  A  fe- 

moral cutaneous  to  the  integuments  of 
the  inner  and  outer  thigh ;  a  tibial 
cutaneous  going  off  a  little  above  the 
inner  condyle,  and  descending  to  sup- 
ply the  inner  leg  as  low  as  the  ankle; 
an  articular  branch  to  the  knee  joint, 
and  an  anterior  cutaneous,  given  off 
near  the  inner  condyle,  to  supply  the 
parts  about  the  patella. 

BRANCHES   OF   THE  SACRAL  PLEXUS   GOING 
TO   THE   THIGH,    (Fig.    263.) 

The  lesser  sciatic  or  ischiatic  nerve 
comes  out  of  the  pelvis,  below  the 
pyriforniis,  in  company  with  the  ischi- 
atic artery,  and  is  divided  into  mus- 
cular and  cutaneous  branches.  The 
muscular  are  called  the  inferior  gluteal 
nerves,  and  go  chiefly  to  the  lower  part 
of  the  gluteus  maximus,  some  of  the 
filaments  being  traced  to  the  inner 
thigh  and  perineum. 

Of  the  cutaneous  brandies,  some  go 
to  the  perineum  and  are  called perineal 
cutaneous.  A  branch,,  called  posterior 
cutaneous,  is  traced  over  the  tuberosity  of  the  ischium,  and 
at  the  lower  portion  of  the  gluteus  maximus,  comes  through 
the  fascia  and  descends  along  the  posterior  and  middle 
part  of  the  thigh,  and  the  popliteal  space,  as  low  down  as 
the  middle  of  the  calf  of  the  leg.  In  this  course  it  gives 

FIG.  262  represents  the  anterior  Crural  Nerve  and  its  branches,  a  Point 
where  the  anterior  crural  emerges  from  beneath  Poupart's  ligament,  b  Di- 
vision of  the  nerve  into  its  branches,  c  Femoral  artery,  d  Femoral  vein. 
«  Branches  of  obturator  nerve.  /Saphena  nerve. 


NERVES  OF  THE  INFERIOR  EXTREMITY. 


781 


off  many  cutaneous  branches  to  the  posterior  and  lateral 
parts  of  the  thigh,  as  well  as  a  communicating  branch  in 
the  ham,  to  the  external  saplienus  nerve. 

The  gluteal  nerve  comes  out  of  the  pel-  pIG.  g63. 
vis,  through  the  great  sciatic  foramen, 
along  with  the  gluteal  artery,  and  divides 
into  a  superior  branch,  which  ascends  to 
supply  the  gluteus  medius  and  minimus 
muscles ;  and  an  inferior  branch,  which 
descends  to  supply,  besides  the  glutei,  the 
tensor  vaginas  femoris. 

The  internal pudic  and.  obturator  nerves 
are  described  in  another  place. 

The  great  sciatic  or  posterior  crural 
nerve  (Fig.  263)  is  the  principal  trunk 
from  the  sacral  plexus,  and  the  largest 
nerve  of  the  body ;  it  comes  out  of  the 
pelvis  through  the  larger  sciatic  foramen, 
below  the  pyriform  muscle,  sometimes 
through  it ;  descends  on  the  back  of  the 
thigh,  about  midway  between  the  tuber- 
osity  of  the  ischium  and  trochanter  major, 
over  the  small  rotators,  to  about  half  way 
down  the  thigh,  where  it  divides*  into  the 
popliteal  and  peroneal.  This  division  some- 
times occurs  as  high  as  the  pelvis  at  the 
plexus.  Above  it  is  concealed  by  the  glu- 
teus maximus,  below  by  the  hamstring 
muscles.  The  sciatic  nerve  gives  off  fila- 
ments to  the  hip  joint,  the  various  mus- 
cles in  its  course,  and  the  integuments. 

The  popliteal  nerve  may  be  considered  the  continued  trunk 

FIG.  263  represents  the  Sacral  Plexus  and  its  branches,  a  Lumbo  sacral 
nerve.  6  Gluteal  nerve,  c  Anterior  branches  of  the  four  upper  sacral  nerves. 
d  Sacral  plexus,  e  Internal  pudic  nerve.  /  Lesser  sciatic  nerve,  g  Great 
sciatic  nerve,  h  External  popliteal  nerve,  i  Internal  popliteal  nerve,  j  Its 
brandies  to  the  calf  of  the  leg.  k  Posterior  tibial  nerve.  I  Plantar  nerves, 
m  Anterior  tibial  nerve,  n  Musculo  cutaneous  nerve,  o  Its  cutaneous  portion. 
p  External  saphenus  nerve. 


*T82  NERVES  OF  THE  INFERIOR  EXTREMITY. 

of  the  great  sciatic.  It  accompanies  the  popliteal  artery 
between  the  heads  of  the  gastrocnemius,  to  the  lower  border 
of  the  popliteus  muscle,  where  it  becomes  the  posterior 
tibial  nerve. 

BRANCHES  OF   THE   POPLITEAL  NERVE,  (Fig.  263.) 

External  sapJienus  or  communicans  tibice  comes  off  above 
the  knee  and  descends  the  back  part  of  the  leg,  beneath  the 
fascia,  to 'about  halfway  between  the  knee  and  foot,  where 
it  emerges  and  becomes  cutaneous,  unites  with  a  branch 
from  the  peroneal  nerve,  and  is  then  traced  in  company 
with  the  external  saphenus  vein  on  the  outer  border  of  the 
tendo-Achillis  to  the  back  part  of  the  external  malleolus. 
It  is  distributed  by  numerous  filaments  to  the  integuments 
of  the  heel,  sole,  and  outer  margin  of  the  foot  and  little 
toe,  communicating  likewise  with  the  dorsal  nerves  of  the 
foot. 

Muscular  branches  are  sent  off  to  the  gastrocnemius, 
soleus,  plantaris  and  popliteus  muscles. 

Articular  branches  come  off  and  go  to  the  joint. 

POSTERIOR  TIBIAL  NERVE,  (Fig.  263.) 

The  posterior  tibial  nerve  is  a  continuation  of  the  popliteal, 
and  accompanies  the  posterior  tibial  artery  to  the  back  part 
of  the  inner  ankle,  where  it  divides  into  the  internal  and 
external  plantar  nerves.  The  posterior  tibial  sends  off  in 
its  course  a  few  muscular  branches,  and  a  few  cutaneous 
plantar  branches. 

The  internal  plantar,  (Fig.  264,)  larger  than  the  external, 
goes  along  the  inner  side  of  the  tarsus,  giving  filaments  to 
the  plantar  muscles  and  integuments,  and  at  the  base  of 
the  great  toe  it  divides  into  four  digital  branches,  the  first 
running  along  the  tibia!"  side  of  the  great  toe,  and  the 
other  three  subdividing  so  as  to  supply  the  opposing  sides 
of  all  the  rest  except  the  little  toe. 

The  external  plantar  nerve  accompanies  the  external  plan- 
tar artery  to  the  fifth  metatarsal  bone,  where  it  divides 
into  two  digital  branches,  one  of  which  goes  along  the 


NERVES   OF   THE  INFERIOR   EXTREMITY. 


783 


outer  side  of  the  little  toe,  and  the  other  divides  so  as  to 
supply  the  opposing  sides  of  the  little  and  the  fourth  toe. 
The  external  plantar  supplies  the  various  muscles  in  its 
course,  as  well  as  the  integuments  on  the  outer  margin 
and  sole  of  the  foot. 

PERONEAL  NERVE,    (Fig    263.) 

This  nerve  is  the  external  popliteal,  or  second  division 
of  the  great  sciatic.  It  descends,  along  with  the  tendon  of 
the  biceps,  to  the  head  of  the  fibula,  FIG.  264. 

where  it  divides  into  the  anterior  tibial 
and  external  peroneal  branches.  Be- 
fore this  division  it  sends  off  two  long 
branches,  called  the  external  and  in- 
ternal  peroneo-cutaneous  nerve,  the 
former  being  distributed  to  the  in- 
teguments along  the  fibula,  the  latter 
descending  on  the  gastrocnemius,  and 
about  the  middle  of  the  leg  uniting 
with  the  external  saphenus  or  com- 
municans  tibiae. 

The  anterior  tibial  nerve  (Fig.  259) 
descends  in  front  of  the  interosseous 
ligament,  along  with  the  anterior 
tibial  vessels,  to  the  ankle,  where  it 
passes  under  the  annular  ligament, 
and  is  distributed  to  the  muscles 
and  integuments  on  the  dorsum  of  the  foot  and  the  two 
first  toes ;  it  supplies  the  various  muscles  in  its  course. 

The  external  peroneal  or  musculo-cutaneous  nerve  (Fig. 
259)  descends  the  leg  between  the  peroneus  longus  and 
extensor  longus  digitorum,  and  about  the  middle  of  the 

FIG.  264  represents  the  Plantar  Nerves.  1  Posterior  tibial.  2  Abductor 
pollicis.  3  Flexor  brevis  digitorum.  4  4  Section  of  tendons  of  this  latter 
muscle.  5  5  Abductor  minimi  digiti.  6  Musculus  accessorius.  7  External 
plantar  artery.  8  Internal  plantar  artery.  9  9  External  plantar  artery  in  the 
deep  portion  of  the  foot.  11  Point  where  external  plantar  artery  gets  to  the 
dorsum  of  the  foot.  12  Flexor  longus  pollicis.  13  Posterior  tibial  nerve. 
14  Internal  plantar  nerve.  15  External  plantar  nerve.  16  Digital  nerves. 


784 


SUMMARY   OF  MUSCLES. 


leg  it  penetrates  the  fascia,  and  goes  to  the  outer  malleolus, 
where  it  divides  into  external  and  internal  branches — the 
former  supplying  the  integuments  on  the  three  outer  toes, 
and  connecting  with  the  external  saphenus ;  the  latter 
being  distributed  on  the  two  first  toes,  and  communicating 
with  the  internal  saphenus. 


SUMMARY  OF  THE  MUSCLES   OF  THE  INFERIOR  EXTREMITY. 


MUSCLES    OF    THE    THIGH. 


ON    THE    FRONT. 

Tensor  vaginae  femoris. 

Sartorius. 

Rectus. 

Vastus  internus. 

Vastus  externus. 

Crureus. 

ON    THE    BACK. 

Biceps. 

Semitendinosus. 

Semimembranosus. 


INNER    MUSCLES. 


Iliacus  internus. 
Psoas  magnus. 
Pectineus. 
Adductor  longus. 
Adductor  brevis. 
Adductor  magnus. 
Gracilis. 


MUSCLES    OF    THE    LEG. 


ON    THE    FRONT. 

Tibialis  anticus. 
Extensor  longus  digitorum. 
Extensor  longus  pollicis. 
Peroneus  tertius. 

ON  THE  OUTER  LEG. 
Peroneus  longus. 
Feroneus  brevis. 


ON    THE    BACK. 

Gastrocnemius. 

Plantaris. 

Popliteus. 

Flexor  longus  pollicis. 

Flexor  longus  digitorum. 

Tibialis  posticus. 


ON    THE    DORSUM. 

Extensor  brevis  digitorum. 
Interossei  dorsales. 


MUSCLES    OF    THE    FOOT. 

Musculus  accessorius. 


ON    THE    SOLE. 


Abductor  pollicis. 
Flexor  brevis  digitorum. 
Abductor  minimi  digiti. 


Lumbricales. 

Flexor  brevis  pollicis. 

Adductor  pollicis. 

Flexor  brevis  minimi  digiti. 

Transervalis  pedis. 

Interossei  plantares. 


'      RELATIONS  OF  THE  MOUTH  WITH  THE  EXTREMITIES.          785 

The  muscles  of  the  hip,  which  are  most  generally  found 
among  those  of  the  lower  extremities,  will  he  found  in  the 
summary  of  the  muscles  of  the  trunk. 

ANATOMICAL  AND  PHYSIOLOGICAL  RELATIONS  OF  THE  MOUTH 
WITH  THE  EXTREMITIES. 

Under  this  head  we  shall  only  refer  to  the  well  known 
pathological  fact  of  trismus  or  locked-jaw  resulting  from 
injury  to  the  toes,  thus  establishing  a  relation  between  the 
mouth  and  inferior  extremities.  This  relation,  in  all  prob- 
ability, occurs  through  the  spinal  marrow  and  fifth  pair  of 
nerves. 

The  relations  of  the  mouth  with  the  superior  extremities 
are,  no  doubt,  equally  close  and  important  with  those  of 
the  inferior  extremities. 


THE  END. 


50 


INDEX, 


A. 

Abdollaliph,  an  anatomist,      PAGE    35 

Abdomen,        .         .      ,  *• ';  ,  .;        537 

Abdominal  spinal  nerves,     .        .  634 

Abdomino-crural  nerves,         .        634 

Abducentes  nerve,        .         .         .  353 

Abducentes-oculi  nerve,        ,  .       423 

Abduc  tor  indicis,         .         .        .  723 

Minimi  digiti,   .        .        .        723 

Minimi  digiti  pedis,  .  767 

Oculi'       .  .350 

Pollicis,         .        .        .        .722 

Pollicis  pedis,'  ...       766 

Aberrations  of  light,     .        .        .348 

Absorbents  of  the  trunk,          .       590 

Absorption  of  the  skin,         »        .  130 

Accelerator  urinae,  .        .        ,        679 

Accessory  ligament,     .        .        .  705 

Acervulus,       ....       414 

Acetabulum,        ....  474 

Acini  of  Malpighi,  ...        639 

Acini  of  the  liver,        .        .        .582 

Active  organs  of  the  head,      .       222 

Of  inferior  extremity,   .        .  757 

Of  mastication,         .        .       294 

Of  the  superior  extremity,     .  709 

Of  the  trunk,     .        .       481,  537 

Adamantine  organ,       .         .        .  253 

Adductor  minimi  digiti,  .        .        723 

Brevis, 760 

Longua 760 

Magnus,         ....  760 
Oculi,       ....       350 
Pollicis,         .        .        .  723,  768 
Adipo-glandular  fascia,  .        .       546 
Adipose  tissue,     .        .         .         .79 
Quality  of,        ...         79 
^Ethmoid  cells,  Anterior,     .        .  382 
Posterior,        .       382 
^Ethmoidal  notch,         .        .        .  179 
Air  cells,         .        .        .        .;      610 
Alae-minores,       .        •   ^  .        .  192 
Alar-cartilages  of  nose,   .        .       380 
Ligaments,          .        .        .      755 
Albicantia,      ....        412 
Albinus,  (a  distinguished  anato- 
mist,)   38 

Albumen, 52 

Chemical  analysis  of,        .         52 

Alcmaeon,  (father  of  anatomy,)        33 

Alveolar  arch,     .        ,        .        .199 

Processes,        .        .  199 


Alveolar  artery,  .       ;. '  •. 
Alveoli,  .... 
Alveolo-dental  periosteum, 
Amnion, 

Amphiarthrosis,  . 
Amygdaloid  lobe, 


.  436 
162 
.  324 
671 
.  352 
405 

AnaTfascia,          .  676 

Anastomotica  magna,  .  774,  730 
Anastomosis,  .  .  .  .90 
Anatomy — antiquity  of,  . 

History  of,    .         .        .        .     ! 
First  cultivator  of,    .        • 
Science  of,    .        .        *        .33 
Its  divisions,     .        .    <    •  I       58 
Comparative,        .        •        •     58 
Human,    .        ..       - ,-    ..         59 
Pathological,         >.     »;      .    59 

Special 59 

Surgical,       .        .        .         .59 
Anatomical  Schools  of  Athens 

and  Alexandria,        .   .,    *        .     34 
Anconeus  muscle,    .        .        .        714 
Andral,         .         .        .        .,.       .     39 
Anfractuosities  of  brain,          •        409 
Angle  of  the  pubis,       .        .         .  474 
Angles  of  occipital  bone,         .        184 
Of  parietal  bone,     .        .        .181 
Angular  motion  of  joints,.       .        153 
Angularis  artery,    *      ...  431 
Animal  matters  destitute  of  nitro- 
gen,        .          ....    56 
Annular  ligament  of  radius,     .        706 
Ligament  of  wrist-joint,        .  707 
Ligaments,        .        .         .        725 
Anterior,        .         .        .  725 
Posterior,  ...        725 
Anterior  atlanto-axoid  ligament,     460 
Anterior  auris,        .        .  362 

Cerebral  artery,      .  .  425 

Cervical  plexus,          .  511 

Circumflex  artery,  .  .  728 

Clinoid  processes,       .  193 

Communicating  artery,  .  .  425 
Costo-sternal  ligaments,  .  467 
Transverse  ligament,  .  466 
Crucial  ligament,  .  .  753 
Crural  nerve,  .  .  635,  779 

Dental  canal,  ...  264 
Nerve,  .  .  .  .264 
Inferior  spinous  process,  .  472 
Interosseii,  ....  724 
Jugular  vein,  .  .  .  509 
Interosseous  artery,  .  .  733 


788 


INDEX. 


Anterior  ligament  of  head  of  ribs,  466 
Of  ankle  joint,     .        .       755 
Of  metacarpus,        .        .  709 
Mental  foramen,         .        .        209 
Occipito-atloid  ligament,        .  457 
Palatine  canal,  ...        201 
Plantar  ligaments,  .        .        .  757 
Ligaments  of  phalanges,     .       709 
.  Pubic  ligament,       .        .        .478 
Pulmonary  plexus,      .       500,  612 
Sacral  foramina,     .         .         .451 
Sacro-iliac  ligament,  .        .        476 
Sacro-sciatic  ligament,   .        .  476 
Spinal  arteries,  .        427,  506 

Superior-spinous  process,        .  472 
Temporal  artery,       .        .       432 

Nerves 268 

Tibial  nerve,      .        ;viv  .       783 

Artery 775 

Vein,  .        .-/-.-.        778 

Antcro-lateral  columns  of  spinal 

marrow,    .        .        .       490 
Anti  helix,   .        .        .        .        .361 

Antitragicus 363 

Antitragus, 361 

Ant-eater— teeth  of,  .  .  283 
Antrum  Highmorianum,  .  191,  201 

Aorta, 626 

Abdominal,         .        .       96,  627 

Arch  of,         ...    96,  626 

Branches  of,     .        .        .   97,  98 

Origin  of,  .        .        .96 

Thoracic,         .         .        .96,  626 

Aortic  plexus,  .        .        .632 

Apes — diciduoui  teeth  of,     .        .  275 

Aponeurosis  palmaris,     .        .       726 

Plantaris,       .        .        .        .771 

Apophysis,       .        .        «        .        165 

Apparatus,  .         .        .        .        .     41 

Ligamentosus-colli,  .        .       459 

Appendages  of  the  eye,        .        .  349 

Of  skin,     .        .        .        124,132 

Of  mucous  membrane,  .        .  141 

Appendices  epiploicae,       .        .      572 

Appendix  vermiformis,        .        .  572 

Aqua-labyrinthi,      .        .        .        374 

Aqueduct  of  the  cochlea,      .  187,373 

Of  Fallopius,     .        187,  188,  371 

Of  Sylvius,  .         .        .         .414 

Of  vestibule,    ...        188 

Aqueous  humur 342 

Arachnoid  canal,  .  .  .  419 
Arachnoidea  tunica,  .  .  .  388 

Arbor  vitae 406 

Arch  of  the  aorta",  -  ...  96 
Arches  of  the  palate,  .  .  307 
Arch  of  the  pubis,  .  .  .  474 
Arciform  fibres,  .  .  .  401 
Arcus  profundus  artery,  .  731,  734 
Areolar  tissue,  ...  75 
Armadillo,  Teeth  of,  .  .  .  283 


Arm-bone,       ...»       692 

Arteria  centralis,         .        .        .  339 

Choroidea,        ...        426 

Corporis  cavernosi,       .        .  660 

Dorsalis  penis,          .        .        660 

Helicinse,       ....  660 

Princeps-cervicis,     .         .        504 

Pollicis,         .        .        .        .776 

Innominata,      .         .          96,  627 

Arteries.  Contractility  of,    .        .     92 

Coronary,          ...          96 

Elasticity  of,         ...     92 

Arteries  of  the  forearm,   .        .      731 

Of  the  oesophagus,         .        .  497 

Sheath  of,         ...          93 

Structure  of,         .        .        .91 

Artery  of  the  bulb,  .        .        660,  680 

Carotid 96 

Of  the  carpus  callosum,  .  425 
External  iliac,  .  .  .98 
Internal  iliac,  ...  98 
Femoral,  .  .  .  .99 
Subclavian,  ...  97 

Arthrodia, 152 

Articular  cavities,  .        .        .        166 

Ligaments,    ....  151 

Articulata,       ....          47 

Articulation  of  atlas 'with  axis,    .  459 

Of  atlas  with  occiput,       .        457 

Of  axis  with  occiput,    .        .  458 

Of  frontal  bone,        .        .        180 

Of  lower  jaw,        .        .        .213 

Of  oblique  processes,        .        457 

Of  ossa  pubis,       .        .        .  477 

Of  palate  bone,        .         .        205 

Of  superior  maxillary  bone,  .  203 

Arytenoid  cartilages,       .        .       526 

Glands,         ....  533 

Arytenoideus  obliquus,    .        .        531 

Trans* versus,         .        .        .  531 

Aryteno-epiglottideus,     .        .       531 

Ascending  cava,  ....  629 

Cervical  artery,     .  .    .*•:.       506 

Colon 573 

Pharyngeal  artery,    .        .       431 
Asclepiades,         .        .        .        .35 

Aselius, 38 

Asternal  ribs,       .        .        .        .463 
Astragalus,      .        .  •        748 

Atlas, 447 

Attachment  of  muscles,  .  .  144 
Attollens  aurem,  .  .  .  362 
Auditory  ganglia,  .  .  .  402 
Auricularis  magnus  nerve,  .  .511 
Muscle,  ....  719 
Auricular  nerve,  .  .  267, 329 


Automatic  systenij 


116 


Nerve, 515 

Aves, 289 

Axillary  artery,  ....  727 

Plexus,     ....  736 


INDEX. 


789 


Axillary  vein, 
Axis, 
Azygos  uvulae, 


736 

448 
309 


B. 


Baboons, 276 

Badger,  Teeth  of,    .        .        .       282 

Barry,  Dr 103 

Bartholine,  Thos.    . 
Basement  membrane,  .        .        .  136 
Base  of  the  skull,    ...        218 
Basilar  artery,      ....  427 

Basilar  process  of  occipital  bone,  183 
Basilic  vein,     ....        735 

Bear,  Teeth  of,    .        .        .        .  282 

Biceps  flexor  cubiti,        .      •.        712 
Biceps  flexor  cruris,     .      *».      .  761 
Bichat,    .        .        .        ....  :.  r      38 

Bicipital  groove,  ».-.-:  .  .-.,  ,  , -,.-  .  692 
Bicuspid  teeth,  .  .t. -:«  232 
Bidlow  Gothofridus,  ...  38 
Bifid  ligament,  ...  704 

Bile, 55 

Birds, 48 

Bladder,  (urinary)  .  .  .643 
Blood-vessels  of,  .  .  649 
Function  of,  .  .  .  .  649 
Ligaments  of,  .  .  .  644 
Nerves  of,  .  .  .  .  649 
Regions  of,  .  ..«.•,.  646 
Structure  of,  >.  .  .  646 

Blood, 39,66 

Agents  preventing  coagulation,  69 
Agents  promoting  coagulation,  69 
Automatic  motion  of,  .  .  74 
Chemical  analysis  of,  .  71 
Color  of,  .  .  .  .68 
Crassamentum  of,  .  .  67 
Force  of,  .  .  .  .70 
Formation  of,  .  .  .  74 
Form  of  blood-globules,  .  71 
Liquor-sanguinis  of,  .  67 
Microscopic  examination  of,  71 
Quantity  of,  ...  68 
Rapidity  of,  .  .  .  '.  .  70 
Serum  of,  .  .  ,  ^t*  67 
Size  of  blood-globules,  .  72 
Smell  of, .  ...  68 
Taste  of,  .  .  .  .68 
Viscidity  of,  .  .  .  70 
Vital  properties  of,  .  .  73 
Blood-vessels  of  abdomen,  .  548 
Of  the  ear,  ....  376 
Of  the  eyebrows,  .  .  355 
Of  the  eyelids,  .  .  .358 
Of  expression,  ...  330 
Of  the  head,  .  .  .  .428 
Of  inferior  extremity,  .  772 
Of  mastication,  .  .  .  298 
Of  the  nose,  .  .  .  383 


Blood-vessels  of  palate,  .  .  309 
Of  papillae,  ...  311 

Of  pharynx 317 

Of  prehension,  .  .  .  226 
Of  salivary  glands,  .  .  302 
Of  spinal  marrow,  .  .  392 
Of  superior  extremity,  .  .  726 
Of  the  teeth,  ...  259 
Of  the  trunk,  .  '.  .  .683 

Bone,  Cellular,  ...  164 

Cancellated 164 

Chemical  analysis  of,  .  162 
Compact,  ....  164 
Composition  of,  .  .  161 
Ethmoid,  .  .  .  .189 
Frontal,  .  .  ,  .  177 
Inferior  maxillary,  .  .  209 
Inferior  turbinated,  .  .  207 
Membranes  of,  .  .169 

Occipital,  ...  182 
Sphenoid,  .  .  .  .192 
Strength  of,  .  .  .  164 
Structure  of,  ...  212 
Superior  maxillary,  .  196 
Tuberosity  of,  ...  198 
Vomer,  .  .  .  .  208 

Bones  of  the  cranium,  .  .  .  177 
Density  of,  .  .  .  163 
Of  the  face,  .  .  .  .196 
Of  extremities,  .  .  163 

Flat 162 

Of  the  foot,  ...  748 
Of  the  forearm,  .  .  .694 
Of  the  leg,  ...  745 
Growth  of,  .  .  .  .  173 
Of  the  head,  ...  163 

Lachrymal 206 

Long,  ....  162 

Malar, 205 

Nasal,  ....  207 
Number  of,  .  .  .  .162 
Palate,  ....  203 
Parietal,  .  .  .  .180 
Short,  ....  162 
Of  the  shoulder,  .  .  .  689 
Situation  of,  .  .  .  163 

Surface  of 165 

Temporal,  ...  184 
Of  the  trunk,  .  .  163,  443 
Unguiform,  ....  206 

Borelli's  estimate  of  heart's  force,  103 

Brachial  plexus,  .  .  513, 736 
Artery,  ....  729 
Nerve, 739 

Brachialis  anticus,  .  .  .  713 
Internus,  .  .  .  .713 

Brachio  radial  ligament,  .  705 
Ulnar  ligament,  .  .  .  705 

Brain,  ....  110,392 
Sinuses  of,  .  .  .  .  396 

Branches  of  axillary  artery,    .       728 


790 


INDEX. 


Branches  of  brachial  artery 

.  729 

39 

Of  radial  artery, 

.       731 

732 

Carpo  metacarpal  articulation 

,     .  708 
.     697 

Broad  ligaments,    . 

557,  666 
.  525 

Bengarius  Jacobus, 
Structure  of,     . 

.     36 
699 

Bronchial  arteries,  . 
Glands, 

611,  627 
.  595 
611 

Caruncula  lachrymalis, 
Myrtiformis, 
Casein,         .... 

.  357 
.      664 
.    53 

.  609 

Chemical  analysis  of, 

53 

Buccal  artery,      •  •  . 
Glands,         .        . 
Nerve,      . 
Teeth, 
Buccinator, 
Bulb  of  the  urethra,    .  •*•;"'*  iv 

c. 

Calamus  scriptorius,    . 
Calcaneo  cuboid  ligament, 
Scaphoid  ligament, 
Calcigerous  tubes,   .        * 
Callus,  formation  of,    . 
Calyces  of  kidneys, 
Calycyform  papilla,     . 
Camper's  fascia, 
Ligament,      .        ."      -:» 
Canal  of  Bichat,  -    .       •  .:'.'•• 
Of  Fontana,  .        ;    •  .:  i 
Of  Petit,  . 

.        434 
.  323 
268 
.  232 
225 
.  658 

.  407 
756 
.  756 
168 
.  173 
641 
.  311 
546 
.  676 
.       419 
.  335 
344 

Cartilage  cells, 
Chemical  analysis  of, 
Form  of,      . 
Functions  of,     . 
Structure  of, 
Cartilages  of  the  larynx,  ' 
Of  the  ribs, 
Cartilaginous  stage  of  bone, 
System,  relations  of, 
Tissue,      .        .    •   ;:   ' 
Casserian  ganglion, 
Cat,  teeth  of,            .        ••>  • 
Cava  Inferior,      .+'••>••'&-  '••<  •*•<• 
Superior,         .    <•>»  ' 
Cavernous  sinus, 
Cavity  of  reserve  of  a  tooth, 
Cell,  nucleated,    . 
Of  Schwann,          -.';<;•• 
Cellular  tissue,     . 
Continuity  of,    .    •  :3jtf*i 

.    157 
157 
.  156 
.       153 
.  157 
525 
.  465 
.        170 
.  159 
156 
.  423 
.       281 
.  100 
101 
.  398 
.       251 
.    63 
39 
.     75 
77 
.    76 

Posterior  palatine, 
Canals  of  bone, 
Cancellated  bone, 
Canine  fossa    •                 • 

.  204 
167 
.  164 
197 

Division  of,       . 
Quantity  of, 
Relations  of,     .    •    •    * 

77 
.     77 
78 
.  164 

Canine  teeth         .                 • 

230 

35 

Capillaries,  structure  of, 

85 

.  271 

Capillary  tissue,  . 
Capsulae  renales,      .    -    .   >• 
Blood-vessels  of,  .        . 
Function  of,      .         . 
Nerves  of,     .        v  'l>r'**' 
Structure  of, 

.    84 
641 
.  642 
642 
.  642 
642 

Chemical  analysis  of, 
Cementum, 
Central  cartilage  of  nose, 
Centrum  ovale  majus, 
Minus, 

.       271 
.  24a 
380 
.  420 
420 
.  730 

Capsular  ligament  of  atlas,  . 
Of  carpus,      .      •  *.-*•  e? 
Of  elbow  joint,  . 
Of  head  of  rib,    '.-  '  -'i> 

.  460 
706 
.     705 
.  466 

Cerebellum, 
Cerebral  surface  of  cranium, 
Cerebro  spinal  axis,        V»" 
Cerin,            .  •      •  *  «'  »  '*  '•'•  '• 

108,  405 
.  223 
386 
.    57 

Of  hip  joint, 

751 

408 

Of  humerus, 
Of  lower  jaw,  . 
Of  metacarpus, 
Of  wrist  joint,  .         .    3 
Capsule  of  Glisson,     . 
Of  the  lens,      .  ,i    «£? 
Caput  gallinaginis,       .  *-•'»••** 
Cardiac  nerves, 
Plexus, 

.  704 
.      214 
.  709 
706 
.  579 
.       344 
.  659 
500 
.  501 

Ceruminous  glands, 
Cervical  nerve,        .     •  -V- 
Plexus,      ;,,-,.-*    .."*> 
Vertebra?,     :    .  -     "•'•• 
Fascia, 
Glands, 
Cervicalis  anterior  artery,    . 
Ascendens, 
Descendens,  . 

.  364 
330 
.  511 

446 
.  522 
.       523 
.  507 

.       493 
.  493 

Carnivora, 
Carotid  arteries,  . 
Artery  internal, 
Canal     . 

273,  280 
96,  627 
425 

.  187 

Posterior  artery, 
Cervico  facial  nerve,    *  *•-    . 
Cetacea,  teeth  of,     . 
Cetyl,  .         ... 

507 
.  329 
289 
.     57 

External  and  internal, 

.       428 

Cheiroptera,     ...       . 

.       279 

INDEX. 


Chemical  relations  of  skin, 
Cheiromys,       .        .        • 
Cheselden,    .... 
Chest,      .        .      (*>,:(.  v 

General  remarks  on,     . 

Cavity  of, 

Diameters  of, 

Form  of  in  Foetus,  . 
Chiasma  of  optic  nerves, 
Chimpanzee,  . 

Deciduous  teeth  of, 
Chondrin, 

Chemical  analysis  of,    . 
Chorda  tympani  nerve, 

Tendineae,     .        .        . 

Vocales,  »,  ^f*  an 

Chorion,       9i  ;    *  ..,  •«,    ...  • 

Of  tongue,   vK* ?;.;:•*-•,  i. 
Choroid  artery,     .,     .  -    .,;.* 

Coat  of  the  eye, 

Chyle,         .    ..    .;.;i*.-J.  .     ;  nPl 

Chyme,     .        ..       n     ,..v, , 
Ciliae,  .        .        .       .-..-,,i.«t 

Of  epithelium, . 
Ciliaris  muscle,    .        . 
Ciliary  arteries,  long,    ,. 

Short,    .... 

Ganglion,          r      -*»^ 

Ligament, 

Process,    .        •  .*.  ••,!•.» 
Cineritious  matter, 
Circle  of  Willis,      .     ^ 
Circular  sinus  of  Ridley, 
Circulation,  development  of, 

Foetal,  .     .  ......  ,,v>h 

General,  . 

Lymphatic,   . 

Portal, 

Pulmonary,   . 

Venous,     . 

Circumduction  of  joints, 
Circumflexa  illii  artery,  . 
Circumflexus  palati,    ,:       ,j 
Circumflex  arteries, 

nerve,  .... 
Clavicle,  .        .  '*".  ;1 

Function  of,  .        :     '  « 

Structure  of,     . 
Clefts  or  fissures  of  bone,    . 
Cleft-palate,    . 

Clitoris 

Coccygeus  muscle,  . 
Coccygeal  ganglion, 
Coccyx,  .... 

Development  of,    . 

Cochlea, 

Cochlear  nerve,  .        . 
Coecum,  .... 
Collar  bone, 

Colon,      .... 
Columbus,    .... 


.  131 

278 

.    38 

460 

.  468 

468 

.  469 

469 

.  421 

.       273 

.  274 

55, 158 

.    55 

266,  329 

.  619 

.       528 

.  671 

.       378 

.  426 

.       334 

.    39 

39,  564 

.  356 

136 

.  326 

346 

.  346 

346,  516 

.  335 

.       336 

.  109 

427 

.  398 

104 

.  105 

89 

.  105 
87 

.  101 
99 

.  153 

.        548 

.  308 

728 

.  739 

691 

.  692 

.        692 

.  167 

307 

160,  662 

679 

.  515 

.       453 

.  454 

371 

.  375 

572 

.  691 

.       573 

.  371 


Columnae  carneae,        .        .        .  619 

Columna  of  nose,    .        .        .       381 

Columnar  bladder,       .        .        .  648 

Epithelium,       ...        136 

Commissura  mollis,       .        .        .  416 

Commissure  of  cerebellum,      .       403 

Common  carotid  arteries,     .         .  259 

Communicans  noni  nerve,        .       512 

Tibial  nerve,         .        .        .782 

Compact  bone,         .        .        .        164 

Comparative  anatomy  of  the  teeth,  268 

Complexus  muscle,  .        .       494 

Compound  fibrous  membranes,     .  155 

Compressor  nasi,     .        .        .       325 

Penis,  ....  678 

Urethra,  ....       680 

Conarium,    .        .        .        .        .  414 

Concha, 362 

Condyles, 165 

Of  the  humerus,        .        .       693 

Of  femur,     .         .        .        .744 

Of  occipital  bone,     .        .       183 

Conical  papilla?,    .        .        .        .311 

Consistence  of  muscles,  .         .        143 

Constrictor  isthmii  faucium,         .  309 

Pharyngis  inferior,    .        .       316 

Medius,         .        .        .        .316 

Superior,          .        .        .       316 

Contractility,        .        .        .        .65 

Of  arteries,      ...         92 

Conoid  ligament,  .         .         .  703 

Conus  vasculosus,     .        .         .        652 

Converging  fibres  of  cerebrum,   .  410 

Convolutions  of  the  brain,       .       409 

Functions  of,         .        .        .411 

Coraco  acromial  ligament,       .       704 

Brachialis,     ....  713 

Clavicular  ligament,          .       703 

humeral  ligament,          .        .  705 

Coracoid  apophysis,          .        .        166 

Ligament,      ....  704 

Cordae  Willisii,         ...       396 

Cord  spinal,          .        .         .         .112 

Cordiform  tendon  of  diaphragm,    552 

Cornea, 340 

Elastica,   ....       342 

Structure  of,         ...  341 

Corniculum  laryngis,       .        .       527 

Cornu  ammonis,  .         .        .         .417 

Corona  ciliaris,        .        .         .       336 

Glandis,        .        .        .        .658 

Coronary  arteries,    .      .  96,  624,  627 

i     Artery,         .        .        .        .553 

Ligament,        .        .         577,  706 

Veins 624 

Coronoid  process  of  ulna,  .  696 
Corpora  Albicantia,  .  .  .  413 
Cavernosa,  .  .  160,  657 
Mammillaria,  .  .  .412 
Malpighi,  ...  639 
Olivaria,  .  .  .  115, 401 


7-92 


INDEX. 


Corpora  pyramidalia,     . 
Restiformia, 
Striata, 

Corpus  callosum, 
Dentatum, 
Denticulatum, 
Fimbriatum,     . 
Geniculatum  externum, 
Geniculatum  internum, 
Highmorianum,     . 
Corpus  Luteum, 
Pampiniforme, 
Psalloides, 
Spongiosum, 
Corpuscle, 

Corpuscles  of  Purkinji. 
Corpusculum  arantii, 
Corrugator  supercillii, 
Cortex  of  the  hair,  . 
Costae,          .... 
Costo  clavicular  articulation, 

Xiphoid  ligaments, 
Cotyloid  cavity, 

Ligament, 
Course  of  muscles, 
Cowper's  glands, 
Cranium,  bones  of,  . 

Its  diameters 
Crassamentum, 
Cremasteric  artery, 
Cricoid  cartilage, 
Crico  arytenoid  ligaments,   . 
Arytenoideus  posticus, 
Arytenoideus  lateralis, 
Thyroideus, 
Crista  of  the  pubis,      . 
Crucial  ridge,  . 

Crura  cerebri,      .        .        . 
Cruraeus,  : 

Crural  nerve, 
Crustacea,        . 
Crusta  petrosa,     . 
Crystalline  lens, 

Chemical  analysis  of,     . 
Structure  of, 
Cubital  fascia, 
Cubitalis  manus  profunda, 
Cuboides,      .... 
Cuneiform  bones  of  foot, 
Bones  of  hand, 
Process  of  occipital  bone, 
Cupola  of  ear, 
Cuspidati,     .... 
Cutaneous  sphincter  ani, 

Branches  of  crural  nerve, 
System,     . 
Tissue, 
Cuticle,    .        .        . 

Cutis  vera, 

Cutis  vera  of  tongue, 
Cystic  duct, 


115,  401 

115,  401 

108,  416 

.  419 

407 

.  417 

417,  671 

.  415 

415 

.  651 

678 

.  654 

.       418 

.  658 

72 

.  168 

620 

.  325 

.        132 

.  463 

703 

.  468 

166,  474 

.  752 

143 

.  660 

177 

.  196 

71 

.  654 

.      526 

.  528 

,       530 

.  530 

.       529 

.  473 

183 

.  411 

759 

.  635 

293 

.  243 

343 

.  343 

,       344 

.  725 

733 

.  749 

750 

698 

.  183 

372 

.  230 

574 

.  779 

134 

.  123 

127 

.  325 

378 

.  585 


D. 

Dartos, 650 

Deep  cervical  fascia,  .  .  522 
Deep  perineal  fascia,  .  .  .  676 
Deltoid  fascia,  ...  725 
Deltoid  ligament,  .  .  704,  756 
Deltoid  muscle,  ....  710 
Dens  sapientiae,  .  .  .  233 
Dental  arches,  .  .  .  255 
Dental  canals,  .  .  .  .198 
Dental  groove,  primary,  .  .  249 
secondary,  .  251 
Dental  pulp,  ....  234 

Dentata, 448 

Denticulata  ligamenta,    .        .        389 

Dentine, 238 

Blood-vessels  of,       .        .        240 

Formation  of,   .        .  •    241,  242 

Structure  of,     .        .        .        239 

Dentition  in  mammalia,       .        .  272 

Dependency  in  organization,  .          44 

Depressor  anguli  oris,          .         .  224 

Labii  inferioris,         .        .        225 

Labii  superioris  alaeque  nasi,  224 

Oculi,       .         ...        350 

Descendens  noni-nerve,        .         .511 

Descending  colon,   .        .        .        573 

Development  of  bone,  .        .  170 

Of  circulation,         .        .         104 

Of  frontal  bone,     .        .        .180 

Of  lachrymal  bones,          .        207 

Of  muscular  system,      .        .  146 

Of  nasal  bones,          .         .        207 

Of  palate  bones,    .        .         .205 

Of  parietal  bones,     .        .        182 

Of  superior  maxillary  bone,  .  203 

OfVomer,        ...        208 

Diameters  of  cranium,         .        .  196 

Diaphragm,     ....        551 

Blood-vessels  of,   .        .        .  553 

Nerves  of,        ...        554 

Diarthrosis,  ....  152 

Diembroeck,  ....          38 

Digastric  lobe,     .     •  ,     •  .        .  405 

Muscle,    .      -..-  •-.        .        304 

Nerve 329 

Digital  arteries,      .        .         733,  777 
Digital  fossa3,  .        .         .        ]79 

Nerves 740 

Dilator  nasi  muscle,  .  .  326 
Direction  of  muscles,  .  .  .143 
Discharges  of  mucous  membrane,  141 
Displacements  of  mucous  memb.  141 
Dissection,  Art  of,  .  .  .  33 
Dissection,  General  rules  of,  .  40 
Diverging  fibres  of  cerebrum,  410 
Dog,  Teeth  of,  .  .  .  .281 
Dorsal  is  carpi  artery,  .  .  731 
Ulnaris,  .  .  .  .733 
Lingua  artery,  .  .  430 


INDEX, 


793 


Dorsalis  carpi  nerve,    .        .        .  740 

Dorsal  ligaments  of  hand,  .  708 
Foot,  .  .  756 
Vertebrae,  449 

Dorsum  of  ilium,          .         .         .  471 

Duct  of  Steno,        .        .        226,  3UO 

Wharton,        .        .        .301 

Thoracic,          ...        122 

Ductus  arteriosus,  .  .  .  620 
Communis  choledochus,  566,  581 
Ejaculatorius,  .  .  653,  655 
Venosus,  .  .  .89,  581 

Duodenum,  .  .  .  ,  565 
Blood-vessels  of,  .  .  .568 
Function  of,  .  .  .  568 
Nerves  of,  .  .  .  .  568 

Dura  mater  of  brain,  .  .  393 
Blood-vessels  of,  .  .  .  394 
Nerves  of,  ...  395 
Reflections  of,  .  .  395 


E. 


Ear, 


360 

External,          ...        361 

Blood-vessels  of,  .        .364,  376 

Nerves  of,        .         .         364   375 

Edentata,  Teeth  of,      .        .        .  283 

Eighth  pair  of  nerves,     .         .        424 

Ejaculator-seminis,      .         .         .  679 

Elasticity  of  arteries,       .         .         92 

Elasticity  of  yellow  fibre,     .         .  149 

Elements  of  human  organization,     50 

Chemical,      .        .        .        .50 

Extractive,       ...          54 

Organic,        .        *    ,,:..       .     52 

Elephant,  Teeth  of,         .         .        283 

Emulgent  artery,          .        .    627,  641 

Enamel,  .        .         .        .        242 

Formation  of,        ...  253 

Organ  of,          .<       .        .        253 

Enarthrosis,         .        «        .        .  152 

Encephalon,     ....        392 

Endocardium,      ....  622 

Ensiform  cartilage,          „       ,;       462 

Ephesius  Rufus,  .         .         .        .35 

Epicranial  aponeurosis,   .        .        325 

Epididymis,          .        .        .        .  652 

Epigastric  region,    .        .        .        538 

Epiglottic  glands,         .        .        .533 

Epiglottis,       .        .        ...        527 

Epiphysis,    .        *        .     ,:.  .     .  165 

Epiploic  arteries,    .        *      ..       563 

Epithelia,     .        .        .     .  *        .    39 

Epithelium,     .        .     vv,       •        135 

Ciliated,        .    .,.»  ...        .  136 

Columnar,        .     »  .    . .<  .        136 

Scales  of,      .        .M  t;v       .  135 

Equator  Oculi,         »;;;  -  4  ,. 2,  .        338 

Erasistratus,         .  - r*    .  .,        .     34 

Erectile  tissue,        .       v     ;*       160 


Erector  clitoridis,        .        .        .680 

Penis,         .        .        .       678 

Spinae,    .         .        .         .492 

Erinacidae.      ....        279 

Eruption  of  permanent  teeth,       .  245 

Temporary  teeth, 

Ethmoid  bone,     ....  189 
Articulations  of,       .      ,  . 
Development  of,   .       -.        .  192 
Structure  of,    .         .        .        191 

Cells, 190 

Eustachian  tube,     .         137,  187,  366 

Valve,        .        .        .617 

Eustachius,      .         ...        *         37 

Excito-motory  nerves,    .        .       HO 

Excretion  theory  of  dentine,         .  241 

Exhalants,       ....         86 

Exhalation  of  the  skin,         .         .  385 

Expiration,       ....        612 

Expression,  Blood-vessels  of,        .  330 

Nerve  of,          .         .        .        327 

Organs  of,     .         .        .         .  324 

Extensor  brevis  digitorum  pedis,     769 

Accessorius  indicis,  .        721 

Carpi  radialis  longior,   .        .  718 

Brevior,    .        718 

Ulnaris,          .        .        .719 

Communis  digitorum,       .       719 

Pedis,          .,       .762 

Minor  pollicis,         ...    .    *        720 

Major  pollicis,       .        .        .  720 

Ossis  metacarpi  pollicis,  .        720 

Proprius  pollicis,  .         .         .  763 

External  carotid  artery,  259,  428,  501 

Circumflex  artery,    .         .        773 

Costo  transverse  ligament,     .  466 

Cutaneous  nerve,      .         .        739 

Ear, 361 

Epigastric  artery,     .        .        548 

Iliac  artery,  ....     98 

Vein,         ...        779 

Ilio-inguinal  nerve,        .         .  635 

Jugular  vein,    .         .        262,  507 

Lateral  lig.  of  ankle  joint,     .  756 

Elbow  joint,      705 

Knee  joint,     .  753 

Wrist  joint,       707 

Malleolus,     .        .        .         .747 

Maxillary  artery,      .         .        504 

Oblique  muscle,     .        .        .  539 

Peroneal  nerve,        .        680, 783 

Plantar  artery,      .         .        .  777 

Nerve,         .        .        782 

Pudic  artery,  .         .        548,  773 

Respiratory  nerve,   .        .       514 

Saphena  vein,       .        .         .  778 

Saphenus  nerve,       .        .        782 

Sphincter  ani  muscle,   .         .  574 

Eye,  form  of,  .  v    ..       .       331 

Situation  of,   .        .        .        331 

Eyeball,  Nerves  of,      .     ,'.        .  346 


794 


INDEX. 


Eyebrows, 

Blood-vessels  of, 

Nerves  of, 
Eyelids, 

Blood-vessels  of, 

Nerves  of,     . 

Structure  of,    . 

F. 


354 
355 
355 
355 
358 
358 
355 


Fabricius, 37 

Face,  bones- of,         ...        196 

Facial  artery,      .      226,  428,  430,  504 

Nerve,  .         .        327,  423 

Falciform  ligament,     .         .  556,  576 

Fallopian  tubes,        .         .         .        671 

Fallopius  Gabriel,        .        .         .37 

Aqueduct  of,    .         .         .         187 

False  pelvis 478 

Falx  major,     .        V.         .        179 

Cerebelli,    .        .        .         .395 

Cerebri,  .   -  - .  .     v  .        .       395 

Fascia  .        .     '  .        .        .1^54 

Brachialis,         .        .         .        725 

Dentata,        '.        ..        .        .  417 

Femoris,          .         .         .       770. 

Iliaca, 551 

Lata,  .  .._  .  '  .  770 
Plantaris,  .  "«  ,  .  .771 
Profunda,  .  '  ' '. ,  '•  .  522 
Propria,  .  ,  .  .  547 
Transversalis,  .  .  .  546 
Of  inferior  extremity,  .  .  769 
Of  the  neck,  ...  522 

Of  leg 771 

Superficial  of  abdomen,  770,  545 

Of  the  pelvis,    ...        675 

Of  the  perineum,  .        .  677 

Of  the  superior  extremity,       724 

Fasciculi,         .        .         .        .        HI 

Fasciculus  of  muscle,  .         .144 

Fats,        .      |»:    .  ••.        .        .         56 

Fauces,         .•"     ....  307 

Femoral  artery,       .        .          772,  99 

Nerve,  .         .        .         .635 

Vein,         ...        778 

Femur, 742 

Fenestra  ovalis,       .         .         .        366 

Fibre'of  animallife,    .'.      .-        .145 

Muscle,     .  144 

Organic  life,          ,  '      .  145 

Fibres  of  the  pilp,          .   '    .       238 

Fibrin.         .        .        .-'•"    .'       .     52 

Chemical  analysis  of,         .         53 

Of  muscle,    .         .         .         .146 

Fibro  cartilages,      ,' '     ,        .       455 

Cartilaginous  bodies,     .         .  148 

Cartilaginous  tissue,          .        159 

Functions  of,          .         .         .159 

Fibrous  capsules,     .        .        .       154 

Envelopes,      .         .148,  154 


Fibrous  envelope  of  brain,      .       155 

Coat 135 

System,  relations  of,          .        156 

Fibrous  tissue,      .        .         .        .148 

Elasticity  of,     .     •  >fc;      .        148 

Extensibility  of,    .         .         .148 

Flexibility  of,   .  148 

Tissue,  white,         .         .  149 

yellow,  .         .        149 

Fibula, 746 

Fifth  pair  of  nerves,  .  .  422 
Fifth  ventricle,  .  .  .  .419 
Filliform  papillae,  .  .  .311 
First  pair  of  nerves,  .  .  .  420 

Fishes, 48 

Fishes,  Teeth  of,         ...  292 
Fissure,  Glasserian,         .         .        185 
Fissure  of  Sylvius,       .         .         .  193 
Flat  bones,       ....        162 
Flexor  accessorius,      .         .        .  767 
Brevis  digitorum  pedis,      767 
Minimi  digiti,  723,  768 
Pollicis,      .      722,  768 
Carpi  radialis,          .         .  715 
Ulnaris,     .        .        716 
Communis  digitorum  pe- 
dis, .         .         .765 
Longus  digitorum  pedis,      765 
Pollicis,       .    717,766 
Digitorum  profundus  per- 

forans,    .         .     ;"  716 

Sublimis  perforatus,   716 

Floating  ribs,  ....       463 

Flocculus, 405 

Foetal  circulation,    .         .        .        105 

Follicle,  Simple 119 

Follicle  of  the  hair, 

Follicles,  Gastro-enteric,     .        .  140 

Of  mucous  membrane,      .        137 

Fontanelle,  Anterior,  .  ''  I"V'*;      •  181 

Fontanelle,  Posterior,      ;''••"*.       181 

Fontanelles,          .        .        .         .222 

Foramen  auditorium  externus,        188 

Internus,     .  188 

Caroticum,  .  .  .  187 
Coecum,  .  .  .  .179 
Commune  anterius,  .  .  416 
Posterius,  .  .  416 
Incisivum,  .  .  .  201 
Intervertebral,  •**'*•.;'  .  444 
Lacerum  medius,  .  .  194 
Posterius,  .  .  .  183,  187 
Superius,  .;  -?v •'-•.'•  194 
Magnum,  .  .  "  V'  .  182 
Of  Monroe,  .  ..  :- i  418 

Opticum 194 

Ovale,  .  .  .  -V  194,  618 
Rotundum,  .  .  .  194, 366 
Of  Scemering-,  .  .  .  340 
Spheno-palatine,  .  .  .  205 
OfWinslow,  ...  558 


• 


INDEX. 


795 


Foramina  of  bone, 
Orbital,   . 
Of  sup.  maxillary 
Of  temporal  bone 
Thebesii,      . 
Formative  force, 
Formation  of  dentine, 
Enamel,     . 
Hair,      . 
Forms  of  articulation, 

.  167 
179 
bone,  202 
.        188 
.  618 
65 
.  241 
253 
.  133 
152 
.  417 

Gasserian  ganglion,         .        187,  262 
Gastric  artery,     .         .         .  563,  627 
Favuli,        .        .         .        562 
Fluid,      ....  138 

Glands,       ...        562 
Serves,    .         ...        .  500 
Plexus,        .,       .      r.        631 
Gastrocnemius,    .....  764 
Gastro-colic  omentum,    .         .        556 
Enteric  follicles,     .         .         .  140 
Hepatic  omentum,        .        .      556 
Pulmonary  mucous  membrane,  134 
Gelatine,          .         .        .  *                55 

Fossae,      .... 
Nasal,    .        .        v       . 

166 

.  218 

fc     Digital,     .         .       ...  . 
fc       Innominata,  . 
Navicularis, 
Fourth  pair  of  nerves, 
Ventricle, 
Fourchette,  . 
Fovea  elliptica, 
Hemispherica, 
Froenum  preputii,     . 
Frena  of  the  lips, 
Frenum  epiglottidis, 
Linguae, 
Frontal  bone,  . 
Eminence  on, 
Sinus  of,  . 
Frontal  nerve, 
Fronto-nasalis  muscle,     . 
Function,              .        »        . 

179 
.  361 
662 
.  422 
.        407 
.  662 
.       371 
.  371 
656 
.  320 
527,  529 
.  313 
177 
.  178 
178 
.  353 
.       325 
41 

Gemelli  muscles,         .         .         .    674 
General  development  of  the  skull,  221 
Genio-hyoideus,  ....  305 
Genio-hyoglossus,    .         .         .       305 
Genito-crural  nerve,     .        .         .  635 
Urinary  mucous  membrane,     J34 
Germinal  vesicle,         .         .         .  670 
GimbernaTs  ligament,     .         .       541 
Ginglimus,   152 
Glandular  tissue,     .         .        .        117 
Glands,  Brunner's,       .         .    138,  567 
Buccal,     .         .       .,,'..        323 
Ceruminous,           .        ,        .  364 
Labial,      ....       320 
Lumbar,        ....  593 

Lymphatic,       .        »        .        119 
Mammary,    .         .         .         .118 
Mesenteric,       .         .         .592 
Molar    323 

Of  cartilage,      . 
Of  fibrous  system, 
Of  mucous  membrane, 
Of  the  skin,   . 

158 
.  150 
140 
.  129 
111 

Palatine,   ....       323 
Peyer's,          ...    138,  570 
Odoriferous,      .         .         .        129 
Sebaceous,    .        .     ,    ,        .129 
Structure  of,     .     ,  J     ,  .        117 
Sudoriferous,         .        .         .  128 
Solitary,    ....       139 
Tartar,  322 
Of  the  chest,     ...        595 
Of  the  larynx,       .         .        .533 
Of  mucous  membrane,      .        137 
Of  small  intestine,         .         .593 
Of  stomach,      ...       592 
Of  Tyson,      .        .        .        .656 
Glandulae  Pacchioni,        .        394,  396 
Odoriferse,     .         .        .        .656 
Glandular  artery,     .        .         .     '504 
Glans  clitoridis,  ....  663 
Penis,   ....        658 
Glenoid  cavity,   .        .        .    166,  185 
Ligament,  .         .         .       705 
Gliding  motion  of  joints,      .        .  153 
Glisson's  capsule,    .         .         .        579 
Globules  of  the  blood,      t  .,'       .     39 
Form  of,  ....         71 
Size  of,         .                 .          *  72 

G. 

Galen,  Claudius,      .     .  „  -'„ 
Galeopithecus,     .        •  .     «. 
Gall-bladder,  . 
Blood-vessels  of,   .      .'«• 
Lymphatics  of,          *•- 
Nerves  of,     . 

35 
.  277 

584 
.  585 
585 
.  585 
107 

Lumbar, 
Restiformia,      .    .    i. 
Of  the  spinal  nerves,     . 
Ganglion  of  Arnold, 
Of  Casser,     . 
Of  Cerebellum, 
Of  Cloquet,  .         .     •    . 
OfGasser, 

.  632 
402 
.  391 
518 
.  423 
407 
.  518 
187 

Of  Laumonier, 
OfMeckel,    . 
OfRibes,. 
Semilunar,    .        ,        , 
Gangl  ionic  system,  .        .  ,, 
Gasserian  fissure, 

518 
264,517 
.       516 
.  630 
116 
.  185 

Structure  of,      .        .        .       72 
Globulin,     .....    54 

Globus  major,         *  r..t  .*  "     .       653 

T96 


INDEX. 


Globus  minor,                      • 

653 

Hippocrates,    ....         34 

Glosso-pharyngeal  nerve,        314, 

424 

Hippopotamus,     ....  285 

Glottis,        .        .        .  *     ,.  :     . 

528 

Hog,  teeth  of,          ...        285 

Gluteal  nerves,        .       .>••  .ii  •:»  '  ' 

781 

Horizontal  fissure  of  liver,  .         .  578 

Gluteus  maximus, 

672 

Horner,  39 

Medius,       .         .       >< 

673 

Horse,  teeth  of,    .         .         .        .  287 

Minimus, 

673 
57 

Humero-scapular  articulation,         704 
Humerus,     692 

39 

Development  of                        694 

Goitre,                      ,        » 

525 

Structure  of          ...  694 

Gomphosis,  ....  152, 

228 

Hunters,          .    '    .        .        .         38 

39 

Hyaloid  membrane,     .                 .  345 

Graafian  vesicles, 

669 

Hyena,  teeth  of,      .        .        .        282 

Gracilis  lobe, 

405 

Hyo-epiglottideus  ligament,         .  528 

Muscle, 

759 

Hyoid  artery,  .        .        .       430,  503 

Gramenivora,  Teeth  of,  . 

272 

Hyoglossus,  1      .        .        .        .306 

Granules  pigment, 

132 

Hypochondriac  regions,  .        .       538 

Great  cerebral  commissure, 

419 

Hypogastric  artery,      .        .         .98 

Sciatic  nerve,  . 

781 

Plexus,        .        .        632 

Greater  circulation,     . 

625 

Regions,  .        .         .538 

Coronary  vein, 

6-24 

Hypoglossal  nerve,          .       425,  510 

Meningeal  artery, 

433 

Sacro-sciatic  ligament,    . 

476 

I. 

Splanchnic  nerve, 

630 

Grooves  of  bone,      • 

166 

Iliac  regions,        ....  539 

Guinterius  John,           .        . 

36 

Iliacus  internus,       .        .        .        550 

Gums,      

321 

Ilio-coecal  valve,           .        .        .  573 

Vascularity  of, 

321 

Ilio-colic  valve,        ...        573 

Gustatory  nerve,     .        .        267, 

314 

Ilio-hypogastric  nerve,     .     .        .  635 

Gutters  of  bones, 

167 

Ilio-lumbar  ligament,       .        .        475 
Scrotal  nerve,       .        .        .  635 

H.  ..-.'•• 

Ilium,      ....        470,  568 

. 

Blood-vessels  of,   .        .         .  571 

55 

Function  of,              .        .        571 

Hair  follicle,    .... 

132 

Nerves  of,     .        .        .        .571 

132 

Impressions  on  bone,       .        .        165 

Hand,      

697 

Incisive  nerve,     ....  267 

Harmonia    .                                   • 

152 

Incus,       368 

Harvey,  

37 

Inferior  articular  artery,      .        .  775 

Haversian  canals, 

168 

Inferior  cava,  .         .        .        100,  629 

Head,  active  organs  of,  . 

222 

Cerebellar  artery,          .         .  427 

Heads  of  Bones, 

1G5 

Cervical  ganglion,     .        .        521 

Heart  102, 

614 

Coronary  artery,   .        .  227,  430 

Blood-vessels  of,   . 

623 

Tosto-sternal  ligaments,  .        467 

Function  of,      . 

624 

Dental  artery,       .        .  262,  433 

Nerves  of,     . 

624 

Nerve,  ...        267 

Sounds  of,        ... 

625 

Gluteal  nerves,     .         .        .  781 

Structure  of,         ... 

622 

Haemorrhoidal  artery,    g  .        680 

Hedge-hogs,    .... 

279 

Labial  artery,        .         .  227,  430 

f-r       i  .                           ° 

Helix,  i 

361 

Laryngeal  artery,     .        .        503 

Hemispheres  of  brain,     .        -i1 

408 

Nerve,          .         .  500 

Hemispherical  ganglia, 

409 

Vein,        .        .        509 

Hepatic  artery,       .        .        579, 

627 

Longitudinal  sinus,        .  395,  397 

Ducts,    .        .        .        ; 

581 

Maxillary  artery,      .        .        433 

Plexus,      .  JMnwNKPv 

631 

Bone,   .         .         .209 

Veins,    .        .   •     .        -. 

581 

Articulation  of,  213 

Herophili  torcular,  .     -  »        i"  '"' 

184 

Structure  of,  .     212 

Herophilus,           .        .     ;    .        . 

34 

Nerve,       .      267,  423 

637 

Miningeal  artery,  .         .         .  431 

Hippocampus  major,       .       41], 
Minor,   . 

417 
417 

Mesenteric  artery.    .         .        627 
Inferior  mesenteric  plexus,          .  631 

INDEX- 


Inferior  Musculo-cutaneous  nerve,  635 


Orbital  artery, 

Palatine  artery, 

Palpebral  sinus,     . 

Pharyngeal  artery, 

Strait  of  pelvis,     . 

Thoracic  artery, 

Thyroid  artery,     . 

Vein,   . 
Turbinated  bones, 

Articulation  of, 

Development  of,    . 

Structure  of,     . 

Vermiform  process, 
Inflammation  of  mucous  memb. 


434 
430 
356 
431 
479 
728 
506 
509 
207 
208 
208 
208 
405 

Infra  orbital  arteryT~~        .  227,  261 
Canal,          .        .        198 
Foramen,         .        .  198 
Orbital  nerve,  ...       263 
Spinatus,       ....  710 
Infra- spinous  fascia,          .        725 
Trochlear  nerve,   .        .        .  354 
Infundibuli  of  kidneys,     .        .        641 
Infundibuliform  fascia,         .        .  547 
Infundibulum, .        .         .        .        412 
Of  the  ear,    .         .        .        .372 
Inguino-cutaneous  nerve,          .        635 
Insectivora,  teeth  of,    .        .        .  278 
Insertion  of  muscles,       .        .        144 
Inspiration,  ....  612 

Intercostal  arteries,          .        .        627 
Interarticular  cartilage,  sternum,   702 
Lower  jaw,  214 

Clavicular  ligament,      .        .  703 

Intercostales,  .        .        .        599 

Intercostal  nerves,        .        .        .  633 

Costo-humeral  nerves,      741,  633 

Crural  lamina,       .        .         .  412 

Lobular  fissure,        .        .        583 

Space,    .        .        .583 

Maxillary  bones,      .        .        199 

Ligament  of  lower  jaw,    215 

Pubic  ligament,     .        .        .  676 

Spinales,  ....        496 

Spinous  ligaments,        .        .  457 

Transverse  ligaments,      .        457 

Intertrochanteric  line,     •.*».••;?     .  744 

Vertebral  foramen,  .        .        444 

Ligaments,  .    455,  466 

Intestines,        ....        564 

Inter  transversales,      .        .        .  496 

Internal  abdominal  ring,          .        547 

Carotid  artery,      .        .  425,  428 

Malleolus,         ...        746 

Costo-transverse  ligament,    .  466 

Cutaneous  nerve,      .        .        738 

Epigastric  artery,          .        .  548 

Iliac  artery,      .        .        .         98 

Jugular  vein,         .        .        .  508 

Lateral  lig.  of  ankle  joint,       756 

Elbow  joint,     705 


Internal  lateral  lig.  of  knee  joint,|  753 

of  wrist  joint,  706 

Mammary  vein,        .         .  509 

Maxillary  artery,      260,  429,  432 

Vein,"       .        .  262 

Oblique  muscle,    .        .  .  542 

Occipital  protuberance,    .  183 

Organs  of  sense,   .        .  .  386 

Plantar  artery,          .        .  777 

Nerve,      .        .  .782 

Pudic  artery,    ...  660 

Nerve,         .        .  .781 

Respiratory  nerve,    .        .  512 

Saphenus  nerve,         ,  .  .  779 

Saphena  vein,        .  ».       .  778 

Sphincter  ani,        .        .  .  574 

Interossei  Dorsales,         .        .  769 

Plantares,    .        .  .  769 

Interosseous  artery,         .        .  733 

Muscles,  .        .  .  724 

Nerve,        ,        .  739 

Ligament  of  leg,   .        .  .  755 

Iris, 336 

Blood-vessels  of,   .        .  .  338 

Functions  of,    .        .        .  337 

Nerves  of,    .         .<       .*.  .  338 

Structure  of,     .        .        .  337 

Irregularities  of  the  teeth,   .  .  247 

Ischiatic  nerves,      .        .        637,  780 

Ischio-rectal  fascia,      .        .  .  676 

Ischium, 472 

Island  of  Reil,      .         .         .  .411 

Isthmus  of  the  fauces,     .        .  308 

thyroid  gland,  .  524 

Ivory,      .... 


J. 


Jejunum, 

Blood-vessels  of, 

Function  of, . 

Nerves  of, 
Joints,  angular  motion  of, 

Circumduction  of,     . 

Gliding  motion  of, 

Rotation  of,      .        .* 
Jolivius,       .        .        s-'>- 
Jugular  eminence,  .        . 

K. 

Kangaroo,  Teeth  of,    . 

Keratin, 

Kidneys, 

Blood-vessels  of, 

Function  of,  . 

Lymphatics  of,         # 

Nerves  of,     .     ...».<-, 

L. 

Labial  artery,      .     .  <* 
Labial  glands,         •  v.  . 


238 


568 
571 
571 
571 
153 
153 
153 
153 
38 
183 


282 
54 
637 
641 
642 
641 
64) 


504 
320 


798 


INDEX. 


Labia  majora,      ....  662 

Minora,          .        .         .        662 

Labyrinth  of  the  ear,  .        .         .  370 

Lining  membrane  of,        .        374 

Lachrymal  apparatus,          .        .  358 

Bones,    ...       206 

Articulation  of,      .  207 

Development  of,       207 

Structure  of,          .  207 

Canals,  .  359 

Gland,        .         .        .358 

Blood-vessels  of,        360 

Nerves  of,      .        .  360 

Lachrymal  nerve,    .        .         .       353 

Sac,    .        .<> .         .  359 

Lacteals,          .        .        .        137,  592 

Lactic  acid,          .        .        .         .56 

Lacus,  Lachrymalis,        .        .       355 

Lamina  cribrosa,       .  .  *.    •        .  333 

Spiralis,     .  372 

Lateral  cartilages  of  nose,  .         .  380 

Lateralis  nasi  artery,       .        .       227 

Artery,  .         .         .         .431 

Lateral  ligament  of  atlas,         .       458 

Sinuses,         ....  397 

Ventricles,        ...       417 

Laxator  tympani,        .        .        .  369 

Minor,      ....       369 

Left  auricle,         .         .         .         .620 

Epiploic  artery,         .        ,       563 

Lateral  ligament,  .        -        .  577 

Mesocolon,       .         .        .       572 

Leiberkuhn,         .         .         .         .137 

Leidy 39 

Lemurs, 276 

Teeth  of,  .         .        .        .        276 

Lenticular  ganglion,     .  346,516 

Lesser  circulation,  .         .        .        625 

Coronary  vein,       .        .        .  624 

Ischiatic  notch,         .        .        473 

Meningeal  artery,          .        .  433 

Sacro-sciatic  ligament,      .        476 

Sciatic  nerve,        .         .         .  780 

Splanchnic  nerve,     .         ,        630 

Levator  ani,         ....  679 

Anguli  oris,      .         .         .        224 

Scapulae,        .        .         .  490 

Glandulae  muscle,    .        .        524 

Labii  inferioris,     .  .  225 

Superioris  alsequi  nasi,      224 

Menti,  .         .         .        .225 

Oculi,       ....        349 

Palati,  .         .        .        .308 

Palpebrae  superioris,'        .        351 

Urethra 680 

Lewenhoeck,  ....         38 

Life,  Elements  of,        ...     42 

A  definite  living  origin,  .          42 

Special  form,  .  .43 

Definite  size,      .         .          43 

Definite  structure,  .        .    43 


Life,  a  nutritive  fluid,      .       ;,:        44 

Nutrition,          ...     44 

y     Organic,          .         .        .        116 

Ligament,  .....  148 
OfWinslow,  ...  753 
Of  Zinn,  .  .  .  .350 

Ligamenta  deuticulata,  .  .  389 
Subflava,  .  .  .  .456 

Ligaments,  ....  150 
Of  ankle  joint,  .  .  .755 
Of  the  arm,  .  .  .  .  704 
Articular,  ....  151 
Of  bladder,  ...  644 
Of  Camper,  .  .  .  .676 
Capsular  of  lower  jaw,  .  214 
Of  carpus,  .  .  .  .706 
Of  chest,  ....  466 
Of  foot,  .  «  '  •  .756 
Of  forearm,  ...  705 
Of  hand,  .  .  .  .706 
Of  hip  joint,  ...  751 
Of  inferior  extremity,  .  .  751 
Of  lower  jaw,  exter.  lateral,  214 
Internal  lateral,  .  214 
Inter-maxillary,  .  215 
Of  the  larynx,  .  .  .  527 
Of  metacarpus,  *.:  .  708 
Of  metatarsus,  .  .  .  757 
Mixed,  ....  151 
Non  articular,  .  .  .  151 
Of  pelvis,  ...  475 
Of  phalanges,  .  .  709,  757 
Of  pinna,  ...  364 
Of  shoulder,  .  .  .702 
Of  spine,  ....  454 
Of  superior  extremity,  .  702 
Of  wrist  joint,  .  .  706 

Ligamentum  adscititium,  .  .  705 
Arcuatum,  .  .  .  553 
Bicorne,  .  .  .  .  704 
Latum  pulmonis,  .  .  604 
Mucosum,  ....  755 
Nuchae,  ....  457 
Patellae,  .  .  .  .753 
Teres,  .  474,  577,  706,  752 

Linea  alba, 541 

Aspera,  ....  743 
llio  pectinea,  .  .  471,  478 
Semilunaris,  .  .  .  541 
Trarisversae,  .  .  407,  542 

Lingual  artery,  .  .  428,  429 
Muscle,  .  .  ., '  .  313 
Nerve,  .  314,  425,  510 

Lines  on  bones,    ....  165 

Liquor  of  Coturinius,        ,        •        374 

Morgagni,     .         .         .  344 

Sanguinis,        .        .          67 

Of  Scarpa,         .        .        .374 

Liver, 576 

Blood-vessels  of,  .  .  .  579 
Function  of,  .  .  .  585 


INDEX 


T99 


Liver,  lymphatics  of,  .         .         .  582 

Nerves  of,        ...        582 

Structure  of,          ...  579 

Lobular  biliary  plexus,    .         .        583 

Venous  plexus,        .         .  583 

Lobules  of  the  liver,        .         .        582 

Lobulus  anonymus,      .         .         .  578 

Caudatus,          ...        578 

Quartus,        ....  578 

Spigelii,    .         .       ^        .       578 

Locus  niger,         .        •  ;  ~  »;        .412 

Long  bones,     .         .      ,  ,        .        162 

Longisimus  dorsi,         .    ,  *  .         .  493 

Longus  colli,  .         .  .        487 

Lower  jaw,  articulation  of,          .  213 

Iriterarticular  cartilage  of,       214 

Stylo-maxillary  ligament  of,    215 

Lumbar  arteries,     .         .         .        627 

Ganglia,        .         .         .         .632 

Glands,     ....        593 

Nerves 634 

Plexus,     ....        634 

Regions,        ....  537 

Sacral  ligament,       .         .        475 

Sacral  nerve,         .         .         .  636 

Vertebra,          .        .        .        450 

Lumbricales,        .        .     ••  .'•       .  724 

Pedis,        ....        767 

Lunare,        .....  698 

Lunula, 133 

Lungs, 605 

Blood-vessels  of,  .  .  611 
Color  of,  ....  6J7 
Density  of,  .  *••!  '.  .  606 
Elasticity  of,  .  *  .  r\  •  .607 
Form  of,  .  .  .  .  606 
Function,  ....  612 
Lymphatics  of,  .  .  612 
Nerves  of,  .  .  .  .  612 
Size  of,  .  .  .  .  606 
Specific  gravity  of,  .  .  606 
Structure  of,  .  .  .  608 

Surfaces  of 607 

Lymphatic  circulation,    .        .        105 

Glands,      .         .         .119 

Of  chest,        .        595 

Neck,     .         .  523 

Trunk,      .        591 

Vessels,     .        .        .121 

Lymphatics  of  bone,        ,-:     .       170 

Of  chest,       .        .        .        .  594 

Heart,  ....        595 

Intestines,^        .        «•*      .  593 

Large  intestines, .        .        593 

Liver,        ....  593 

Pancreas,       .         .        .       594 

Spleen 594 

Stomach,      ...        592 

Trunk,      ..'..'.    *..       .  591 

Lyra, 418 


M. 

Macula  germinativa,   ..      .        .670 
Magendie,        .         .        .        •         39 
Magna  pollicis  artery,      t^,.        .731 
Magnum  bone,         .        •    '   >»        699 
Major  helicis,       .  "    *       .        .  363 
Malar  bones,  ....       205 
Articulation  of,  .        .         .  206 
Development  of,    .         .        26 
Structure  of,  .        .  206 

Malar  nerve,  .       V  .;'.       267,330 
Malformation  of  mucous  mem- 
brane,        .         .  .        141 
Malleolus  externus,     .        .        .  747 
Internus,          .        .        746 
Malleolar  arteries,        .        .        .  776 
Malleus,  .        .        .        .        .       368 
Malpighius  Marcellus,         .        .    38 
Mammae,          .        .         .        .        600 
Blood-vessels  of,    .        .         .  602 
Lymphatics  of,       •    .        .       602 
Structure  of,         .,      .  «\      .  602 
Mammalia,  teeth  of          .         49,  270 
Mammary  glands,        .         .         .118 

Mammillaria 412 

Mammillary  eminences,       .         .  179 

Mandrille,       ....        276 

Marsupialia,         ....  282 

Massa-carnea  Jacob!  Sylvii,    .        767 

Masseter  muscle,          .         .         .  294 

Nerve,      ...        268 

Masseteric  artery,        .         .         .  434 

Mastication,  blood-vessels  of,          298 

Nerves  of,      .         .  298 

Mastodon,  teeth  of,         .         .        285 

Mastoid  apophysis,       .         .         .  166 

Portion  of  temporal  bone,         186 

Maxillary  nerve,  .         .         .  330 

Sinuses,  .         .         .        201 

Meatus  auditorius  externus,    363,  377 

Internus,     .       371 

Inferior,         ....  382 

Middle,     ....        382 

Superior,       ....  382 

Urinarius,         .         .         .        663 

Median  cartilage,  of  the  nose,        .  380 

Basilic  vein,          .        .        .  736 

Cephalic  vein,          .        .         736 

Nerve,      ....        739 

Vein, 736 

Lobe  of  the  cerebellum,  .       406 

Mediastinal  arteries,    .        .        .  627 

Mediastinum,  ....        604 

Anterior,       ....  604 

Middle,    ....        604 

Posterior,      ....  604 

Mediastinum  testis,          .        .        651 

Medula  oblongata,        .         .  114,  400 

Nerves  of,        ...       403 


800 


INDEX. 


Medulla  of  the  hair,    .        .        .213 
Medulary  membrane,      *        .        169 
Medula  spinalis,  .         .        .        .387 
Megatheroides,  teeth  of,          .        283 
Meibomian  glands,       .        .        .  357 
Membrana  granulosa,      .        .        670 
Pupilaris,    .        .         .  338 
Tympani,        .        364,  377 
Membrane  basement,  .        .        .  136 
Membranous  labyrinth,  .        .        374 
Membranes  of  bones,   .        .        .169 
Mental  relations  of  the  skin,   .        131 
Mesenteric  glands,       .         •        .  592 
Mesentery,       ....       557 
Meso  colon,  right  and  left,  .        .557 
Transverse,          .       556 
Rectum,   .        .        .        557,  572 
Metacarpo-phalangeal  articula- 
tion,      709 

Metacarpus,         .        .        .         .699 

Ossification  of,  .        .     701 

Metatarsal  arteries,      .         .        .  776 

Metatarsus 750 

Microscopic  anatomy  of  the  pulp,  236 

Middle  artery  of  the  cerebrum,      425 

Articular  artery,       .        .  775 

Cervical  ganglion,        .       521 

Costo  transverse  ligament,  467 

Ear 364 

Meningeal  artery,     .         .  433 

Musculo-cutaneous  nerve,   635 

Straight  ligament,        .       459 

Temporal  artery,      .        .  432 

Turbinated  bones,        .       190 

Minor  helicis,      .        .        .        .  363 

Mitral  Valve,  ...       621 

Mixed  ligaments,          .        .        .151 

Moderator  ligaments,      .        .       459 

Modiolus  of  the  ear,    .        .        .  372 

Molar  glands,          ...       323 

Teeth,        .        .        .        .232 

Moles,  (talpidae,)     ...       279 

Mollusca, 47 

Monkeys,         ....       273 

Monroe, 38 

Mons  Veneris,          .        .        .       662 

Morgani, 38 

Morsus  Diaboli,       ...       671 

Motores  oculorum  nerves,       352,  421 

Externi  nerves,     .     353,  423 

Mouth,     ....        318,437 

Blood-vessels  of,        .         .  323 

Boundaries  of,       .        .       318 

Cavity  of,  .•  -     .        .  318 

Contents  of,  .        .        ,       319 

Dissection  of,    .-    •  >>•'•     .319 

Epithelium  of,        .        .       319 

Mucous  membrane  of,       .  319 

Nerves  of,     ...       324 

Relations  with  the  trunk,  .  684 

Mucous  membrane,     .        .    123,  134 


Mucous  membrane,  discharges  of,  141 
Displacement  of,  .  .  141 
Gastro,  pulmonary,  .  .  134 
Genito,  urinary,  .  .  134 
Inflammation  of,  .  .  .  141 
Malformation  of,  .  .  141 
New  formation  of,  .  .  141 
Of  the  cheeks,  .  .  323 
.  532 


Of  the  larynx, 
Of  the  pharynx, 
Soft  palate,  . 
Relations  of, 
Stricture  of, 
Structure  of, 


323 
.  323 

140 
.  141 

135 


Tumor  of,         .     .        .  .  141 

Vegetation  of,    .        .        .  141 

Mucus,         .        .        .        .  .54 

Mundinus, 36 

Muller 

Multifidus  spinse,          .         .  .  496 

Muscle,  chemical  composition  of,  146 

Nucleated  cell  of,     .        .  145 

Sensibility  of,        .        .  .146 

Muscles,  color  of,    .        .        .  143 

Consistence  of,      .        .  .143 

Direction  of,     .        .        .  143 

Fasciculus  of,        ...  144 

Insertion  of,      .        .        .  144 

Involuntary,          .        .  .  142 

Mixed,      ....  142 

Names  of,     .        .        .  .  143 

Number  of,  .        .143 

Of  the  abdomen,            .  .  682 

Anterior  neck,        .  481 

Arm,  .        .        .  .712 

Back,      ...  682 

External  ear,      .  .  363 

Eye,       ...  349 

Foot,  .         .        .  .766 

Forearm,        .        .  714 

Head,          .   :     .  .  435 

Inferior  extremity,  757 

Internal  ear,       .  .  369 

Leg,       ...  762 

Mouth,       .         .  .223 

Neck,     ...  681 

Nose,           .        .  .380 

Pelvis,     .        .       672,  682 

Perineum,  .         .  .  678 

Shoulder,        .         .  709 

Superior  extremity,  .  709 

On  posterior  neck  and  back,    488 

Origin  of,       .        *        ,s  .  144 

Situation  of,      ...  142 

Structure  of,          ...  144 

Symmetrical,     .        .        .  142 

Their  myolemma,     •     •  .  144 

Muscles  of  thigh,     .         .         .  757 

Sarcolemma,           .  .  144 

Ultimate  fibres  of,     .        .  144 

Fibrils  of,       .  .144 


INDEX. 


801 


Muscular  contraction,  varieties  of,  146 

Sense,  .        .        .        .146 

System,    ....       142 

Development  of,     .  146 

Musculi  accessorii  ad  sacro  lum- 

balem,  .        .         .       493 

Pectinati,  .  .  .  618,  620 
Musculo  cutaneous  nerve,  783, 739, 513 
Muscular  branches  of  brachial  ar- 
tery, .  .  .  .730 
Musculo  spiral  nerve,  .  .  740 
Mylo-hyoideus  muscle,  .  .  304 
Mylo-hyoid  nerve,  .  .  .  267 
Mylo-hyoid  ridge,  .  .  .210 
Myopia,  .  .  .  .  r  ^  343 

N. 

Nail  follicle,        .        .        .  .133 

Nails, 132 

Names  of  muscles,       .    ''.   -  .  143 

Nasal  artery,  ....  435 

Bones,       .        .        .  .207 

Articulation  of,  .  207 

Development  of,  .  207 

Structure  of,       .  207 

Duct,         .        .        .  .358 

Fossae,  .        .       218,  381 

Nerve,       .        .        .  .354 

Prominence,         .        .  177 

Spine,      ...  .177 

Nasmyth 39 

Naso-palatine  nerve,    .        .  .  266 

Ganglion,          .  518 

Navel,         w        .        .         .  .  541 


Navicular  bone, 


Nemisius, 

Nerve  crural, 

Femoral, 
Fibres,  primitive, 
Of  the  bulb, 
OfWrisberg,    . 
Splanchnic, 


697 

.  361 

35 

.  635 

635 

.  108 

680 

.  738,  633 
630 


Nerves,        .        .        .      •.  .110 

Course  of,         .       -.'        .  Ill 

Excito-motory,      .        .  .110 

Of  Bone,  .         .       -.   '     .  170 

Cotunnius,        ."'  ; •'*.-'  .  266 

Mastication,       '  i        .  298 

Motion,     .        .''  ;    .  .110 

Sensation,    .        .        .  110 

The  ear,  .        .        .  .375 

The  eye-brows    .        .  355 

The  eyelids,      .        .  .358 

Inferior  extremity,      .  779 

The  neck,         .         .  .  509 

OZsophagus,         ^«i'H-  .  498 

The  palate,       .        .  .309 

Nerves  of  the  pharynx,   .        .  318 

Salivary  glands,  302 

52 


Nerves  of  the  superior  extremity,  736 
Teeth,   .        .        .262 
Tongue,    .       314,  379 
Trunk,  .        .        .683 
Plexus  of,    .        .        .        in 
Respiratory,     .        .        .  no 
Spinal  origin  of,  .        .        113 
Nervi  pathetici,  ....  353 
Trigemini,        .        .        .        353 
Trochleares,         1        .        .  353 
Nervous  grey  matter,      .        .        109 
Chemical  constituents  of,  109 
Layer,      ....        136 
Tissue,  .        •        .        ,        .  106 
White  matter,  .        .         .        109 
Chemical  constituents  of,  109 
New  formations  of  mucous  mem- 
brane, ....  141 
Ninth  pair  of  nerves,       .       425,510 
Nipple,         .....  600 
Nodule,  .  .  •      _,        .        406 
Non-articular  ligaments,      .        .  151 

Nose, 379 

Cartilage  of,  .        .        .  330 

Notches  of  bones,  • .        .        .        167 

Nucleated  cell,     .         .         .        .64 

Of  muscle,  .        .        .       145 

Nucleus,      .        .        .        ,  .'    .     63 

Number  of  muscles,      '•/".'...       143 

Nutritious  artery  of  arm,     .        .  729 

bones,      .        170 

Nymphae,    ....  160,  662 

o. 

Oblique  inguinal  canal,   .        .       547 

Ligaments,    .         .     459,  706 

Process  of  vertebras, .       445 

Obliquus  capitis  inferior,      .         .  495 

superior,        .        495 

Externus  abdom.  descendens,  539 

Inferior,         ....  351 

Internus  abdom.  ascendens,     542 

Superior,  ...       350 

Oblongata  medulla,      .        .        .114 

Obturator  externus  muscle,     .        674 

Fascia,          .'      .        .        .675 

Foramen,          «        .        .       474 

Internus  muscle,  .        .         .  674 

Ligament,         .        .         .478 

Nerve,          .         .         .    781,  636 

Occipital  artery,     .        429,  431,  504 

Bone,       ...        182 

Articulation  of,     .        .184 

Development  of,       .        184 

Structure  of,         .        .  184 

Occipitalis  major  nerve,      "" "  .       513 

Minor  nerve,       .         .513 

Occipital  protuberance,  external,  182 

Internal,   183 

Sinuses,    .    •>•«•"•    .       393 


802 


INDEX. 


Occipito  axoid  ligament,  .  .  459 
Frontalis  muscle,  .  .  324 
Ocular  fascia,  .  /,  .  .  352 
Odontoid  apophysis,  ">*  .  .  166 
Odoriferous  glands,  .  .  .129 
CEsophageal  nerves,  .  .  500 
(Esophagus,  ....  497 
Arteries  of,  .  .  497,  627 
Olecranon  process,  .  /  ,  .  696 
Olfactory  ganglia,  .  ...  .  420 
Olivaria,  .  .  .  ,  ,  .115 
Olivary  ganglion,  .  .  -,.'  401 
Omentum  majus,  .  :v  .  556 
Minus,  .  .  .  556 
Omo-hyoideus  muscle,  .  .  484 
Opacity  of  the  eye,  '.  .  341 

Opossum 282 

Teeth  of,          .        .        ,282 

Ophthalmic  artery,          .         .       346 

Ganglion,          .         .516 

Nerve,     '     .        353,  423 

Optic  commissure,       .         .        .  421 

Nerve,  ....        420 

Oral  teeth,  .        .        .         .230 

Orbicularis  oris  muscle,  .       226 

Palbebrarum,         .         .        .  326 

Orbital  foramina,     .        .        .        179 

Nerves,    .         .        .        .266 

Processes,   .         .         .        179 

Orbitary  apophysis,      ,        .        .  166 

Orbits  of  the  eyes,       l\  '.        .       217 

Organ,  adamantine,     .        .         .  253 

Definition  of,    .        .         .         41 

Enamel,        .         .        .        .253 

Of  taste,  ....       377 

Of  voice,      .         .         .        .525 

Organic    and    inorganic    bodies, 

difference,          .        .        .57 

Life,          ....       116 

Relations  of  mucous  memb.,  140 

The  skin,          .  131 

Organism,  what  constitutes  it,          41 

Organization,  .         .        .         41 

Development  of,   .        .         .     57 

Human  constituents  of,     .         50 

Its  elements  of  preservation,    45 

Of  man,   ....         50 

Varieties  of,          .         .        .47 

Organs  of  absorption,      .        .       590 

Circulation,          .        .  614 

[Head,  active,  .        .       222 

Neck,  circulatory,       .  501 

Deglutition,      .        303,  497 

'.  Digestion,    .        .        .  554 

;  Abdomen,       .          .       554 

Head,  .        .         .222 

Expression,       .       222,  324 

Generation  of  male,    .  649 

Female,  661 

Innervation,         .        .  509 
Insalivation,    .        .       298 


Organs  of  mastication,          .        .  227 

Prehension,     .         .       223 

Dissection  of,        .  223 

Respiration,    .         .       605 

Sense,        .         .    222,  330 

External,  .        .       331 

Internal,        .         .  331 

Speech,  .        .       222 

The  abdomen,     .        .  527 

Chest,        .         .       596 

Neck  and  back,     .  481 

Pelvis,       .        .       649 

Touch,        .        .   133,  384 

Urination,       .         .       637 

Origin  of  muscles,       .        .        .  144 

Os  calcis,         ....       749 

Cuboides,      .        .         .        .749 

Cuneiforme,      .        .        .        698 

Femoris,       ....  742 

Ilium,        ....        470 

Innominatum,        .         .        .  470 

Development  of,        .        475 

Structure  of,          .         .  475 

Ischium,   ....       472 

Lunare,         .         .         .        .698 

Magnum,      ,   ^       .         .       699 

Ozmasome, 54 

Os  naviculare,         .         .        749,  697 

Pisiforme,      ....  698 

Pubis,  473 

Scaphoides,    .        .        .  749,  697 

Osseous  tissue,         .        .         .        161 

Stage  of  bone,      ..'-.  r.  '      .  170 

Ossification  of  flat  bones,         .        172 

Long  bones,  .  171 

Period  of,          .       172 

Os  tineas, 667 

Ostium  venosum,  .  .  .  618 
Os  unciforme,  .  .  .  .699 
Uteri,  ....  667 
Otic  ganglion,  ....  518 
Oto-conia  of  the  ear,  .  .  375 
Otter,  Teeth  of,  .  .  .  .  282 
Ourang  outang,  •  .  .  273 

Ourlet, 411 

Ovarian  ligaments,          .         .        666 

Ovaries,        .        .        .        .        .  669 

Blood-vessels  of,       .         .        670 

Function  of,          ...  670 

Structure  of,     .        .        .       670 

Ovula  Nabothi,    .        ...     .  -      .  668 

Ovum,      .        .         .      ';.        .       670 

P. 

Pachydermata,  .  .  .  .  283 
Padua — University  of,  .  .  37 
Palate  bones,  ....  203 

Articulation  of,  .  .  205 
Palate  bones— development  of,  .  205 

Foramina  of,    .        .        .       205 


INDEX. 


803 


Palate  bones,  structure  of,  . 
Palate,  arches  of, 

Blood-vessels  of, 
Cleft  of, 
Hard, 

Nerves  of,    . 
Velum  pendulum, 
Palatine  glands, 
Palmaris  brevis,  . 

Longus,     . 
Palmar  ligaments, 
Palpebra,         .         .        . 
Pancreas,     .... 
Blood-vessels  of, 
Function  of,          '.    ;    , 
Nerves  of, 

Structure  of,          .  '.'".    • 
Papilla?,  .... 
Of  the  hair,  . 

Skin,     . 
Tongue,  . 
Blood-vessels  of, 
Minute  structure  of, 
Parenchyma  of  the  lungs, 
Parietal  bones, 

Structure  of,     . 
Protuberance, 
Parotidean  plexus,  . 
Parotid  gland, 

Par  vagum  nerve,    .         424, 
Passive  organs  of  the  trunk, 
Patella,  .... 
Pathetic  nerve,     . 
Pectinalis, 
Peccari,  Teeth  of, 
Pectineus, 
Pectoralis  major, 

Minor,     . 
Pelvic  fascia, 

Vertebra,      .        * 
Pelvis,          .         .        .  .,-     *  5. 
Diameters  of,  .        .y 
Difference  between  male 

female,       .  -. -.i 
False,    .        .        .     \;v- 
General  remarks  upon, 
True,    .... 
Of  the  kidney,  . 

Penis, 

Blood  vessels  of, 
Nerves  of,     . 
Structure  of,    . 

Pepsin 

Pepsin,  chemical  analysis  of, 
Pericardium,     .         , 
Perichondrium,    . 
Perforans  Casserii  nerve, 
Periglottis,  .... 
Perineal  cutaneous  nerves, 

Fascia,          .  .     . 
Perineum  of  the  male,    . 


.  205 

.      307 

.  309 

307 

.  306 

.       309 

.  306 

.        323 

.  723 

715 

.  708 

355 

.  586 

.        587 

.  587 

.       587 

.  587 

.       386 

.  132 

126 

311,  378 

311 

379 

612 

.  180 

182 

.  181 

.       329 

.  299 

498,  509 

.  443 

747 

.  422 

760 

.  287 

760 

.  597 

598 

.  675 

451 

.  470 

.        480 

and 

479 

.  478 

478 

.  478 

641 

.  656 

.        660 

.  661 

656 

54,  563 

.     54 

•        614 

155,  466 

739 

.  378 

780 

.  677 

676 


Perineum,  blood-vessels  of,   .        .  680 

Muscles  of,       ...       678 

Nerves  of,     .        .        .        .  680 

Peroneal  artery,      .        .         .        776 

Nerve,  .        .        .        .783 

Vein,        ...        778 

Peroneus  longus,        .        .        .     763 

Brevis,  .         .        ,763 

Tertius,    ...       764 

Pes  Anserinus,     ....  329 

Hippocampi,     .         .         .        417 

Petrosal  sinus,      .        .        .        .398 

Petrous  portion  of  temp,  bone,        186 

Peyer's  glands,     ....  138 

Phalanges  of  the  foot,      .        .        751 

hand,         .        .  701 

Development  of,  702 

Pharyngeal  nerve  of  par  vagum,     499 

Plexus,        .  499 

Pharynx,         ....        314 

Blood-vessels  of,   .        .        .  317 

Cavity  of,          .  .        317 

Dissection  of,         ...  315 

Nerves  of,         ...        318 

Mucous  membrane  of,  .  323 

Phrenic  artery,        .         .         .        553 

Nerve,    .        .        .        .512 

Plexus,       ...        631 

Pia  mater 389 

Of  the  brain,  .  .  fl  .  399 
Pigment  granules,  .  .  .  132 
Pineal  gland,  peduncle  of,  .  414 

Pinna, 361 

Pisces,  Teeth  of,          ...  292 

Pisiforme,        ....        698 

Pituitary  gland,    .        .        »        .412 

Plantar  arteries,       .        .        .        777 

Fascia,     .        .         .         .771 

Ligament  of  foot,        .        757 

Platysma  myoides,   .        .         .       482 

Plantaris  muscle,          .        .         .  765 

Pleura,    .      .  .      '.        .         .        602 

Function  of,  .         ."        .  605 

Structure  of,    .        .        .        605 

Plexus, Ill 

Aortic,  .  ,-•  '.  *  •-  .  .  632 
Choroides,  :.  v  .  .  418 
Gastric,  ....  631 
Hemorrhoidal,  .  .  .632 
Hepatic,  .  .  ''.-..  631 
Hypogastric,  V  :  .  .  632 
Inferior  mesenteric,  .  631 
Lumbar,  ....  634 
Phrenic,  .  .  •  .  631 
Renal,  .  .  k  .  •'  .  .631 
Sacral,  .  .•••»»'"  ''»  "  .  636 
Sciatic,  .  .  .  .  636 
Solar,  .  r  V  .  631 
Superior  mesenteric,  .  .  631 
Plica  semilunaris,  .  .  .  357 
Pneumogastric  lobe,  .  .  .  405 


804 


INDEX. 


Pneumogastric  Nerve,     .        424,  489 

Pomutn  Adami,    ....  525 

Pons  tarini,     .        .        .        .  1    412 

Pons  Varolii,        .        .        .        .402 

Popliteal  artery,      .        .        .        774 

Vein,    .        .         .   100,778 

•Nerve,     .        .        .        781 

Popliteus  muscle,         .        .        .  765 

Pori  biliarii,    .        .         .     »  .        581 

Porta  of  the  liver,        .',       ."       .578 

Portal  canals,          .        .        •       580 

Circulation,       .        .        .87 

Portal  vessels,  Structure  of,    .         88 

Portio  dura  nerve,       .         .    327,  423 

Mollis  nerve,      -.>,.„       423 

Porus  Opticus,     ....  340 

Posterior  atlanto  axoid  ligament,    460 

Annular  ligament,    .         .        725 

Auricular  artery,  .        .  429,  431 

Auris,       ....        363 

Cerebral  arteries, .         .  426,  427 

Cervical  plexus,        .         .        511 

Circumflex  artery,        .        .  729 

Communicating  artery,     .        426 

Costo-sternal  ligament,          .  467 

Costo-transverse  ligament,       466 

Crural  nerve,        .         .        .  781 

Deep  temporal  artery,      .        434 

Dental  canal,        .         .        .  198 

Dental  nerves,          .        .        264 

Ganglia  of  the  brain,     .        .  414 

Inferior  spinous  process,  .        472 

Interosseii,    ....  724 

Interosseous  artery,  .        .        733 

Interosseal  nerve,          ,        .  741 

Ligament  of  knee-joint,    .       753 

Crucial  ligament,  .        .         .  753 

Meningeal  artery,    .        .        431 

Mental  foramen,  .        .         .  212 

Occipito  atlantal  ligament,      458 

Palatine  canal,      .        .    198,204 

Pubic  ligament,        .        .        478 

Pulmonary  plexus,        .    500,  612 

Pyramids,         .         .         .        402 

Sacro-iliac  ligament,    .        .  476 

Sacro-sciatic  ligament,     .        476 

Scapular  artery,    .        .         •  507 

Spinal  artery,  .         .        427,  392 

Superior  spinous  process,      .  472 

Temporal  artery,      .        .        432 

Nerves,         .        .  268 

Thoracic  nerve,        .         .        514 

Tibial  nerve,         .        .        .782 

Vein,     ...        778 

Artery,       .        .        .776 

Vertebral  ligament,          .        455 

Poupart's  ligament,      .        .         .  100 

Praeputium  clitoridis,       .        .        663 

Prepuce, 656 

Presbyopia,     .        .        .        .343 
Primary  convolutions  of  the  brain,  410 


Primitive  lobe  of  cerebellum, 
Princeps  cervicis  artery, 
Processus  cerebello  ad  testes, 
Process  gracilis,  . 
Process  zygomatic, 


406 
.  431 

407 

.  368 

206 


Profunda'cervicis,  .  .  504,  507 
Spiralis  artery,  .  .  729 
Superior  artery,  .  .  •  729 
Femoris,  .  .  .  773 

Inferior,         ....  730 
Minor,      ....        730 
Promontory  of  the  ear,        .        .  366 
Sacrum,    .       452 

Pronator  quadratus,     .  *•>».<,      .  717 

Radii  teres,       .        .        715 

Prostate  gland,     .        .,',    «        .655 

Structure  of,    .    :».-..        656 

Protein,        .         .        .         .      52,  53 

Psoas  magnus,         .        .  »  .' •»        550 

Parvus,       ....  550 

Pterygoid  artery,     .         .        .        434 

Pterygoideus  externus,        .        .296 

Internus,  .        .       297 

Pterygoid  fossa,  .        .        .        .193 

Nerve,      .        .       265,268 

Pterigo-palatine  artery,        .        .  435 

Pterygoid  process,  .        .         .        193 

Ptyalin 55 

Pubis, 473 

Pudic  nerve,        .        .        .        .680 

Pulmonary  artery,  .        .        611,620 

Circulation,         .  101,  625 

Glands,  .         .        595 

Veins,         .        .        .611 

Pulmones,        ....       605 

Pulp  of  tooth,  cavity  of,       .        .  234 

Microscopic  anatomy  of,       .  236 

Fibres  of,          ...        238 

Vessels  of,    .         .        .        .  234 

Functa  lachrymalia,        .    ,    »       359 

Punctum  aureum,        ....  340 

Lachrymale,     .    4    «*  -n  .       355 

Ossificationis,        .  :     .        .  171 

Pupil  of  the  eye,     .         .        .        337 

Purse-like  fissure,         .        .         .  404 

Pyin,        .         .      U  >^T^.<.         55 

Pyloric  valve,      .    •    .    •    .^      .  563 

Pyraformis,      .     •.<;•.'     -.        674 

Pyramidalia,        .    -.    .  i»    .    •    .  115 

Pyramid  of  the  ear,        v-'?'.        366 

Of  inf.  vermiform  process,  405 

Pyramidalis  muscle,        .         .        545 

Pyramides  Malpighi,    .    •    .         .  640 


Q. 

Quadratus  femoris, 
Lumborum, 
Menti, 

Quadrilateral  spot, 

Quadrumana, 


675 
549 
225 
411 
273 


INDEX. 


R. 

Racoon,  teeth  of,     . 
Rachidian  bulb,  . 
Radial  artery,      >"$*•' 

Nerve,      . 
Radialis  indicis  artery, 


282 
400 
731 
740 
731 


Radiata 47 

Radiated  ligament,  .         .       702 

Ligament  of  head  of  ribs,     .  466 

Radio-carpal  ligament,    .         .       706 

Radius, 694 

Development  of,       .        .        696 

Structure  of,          .        .        .695 

Ramus  of  Ischium,       •.-     .       473 

Pubis,         .        .        .474 

Profundus  dorsalis,      .       741 

Superficial  ant'r  nerve,    741 

Dorsalis,.        .        .       741 

Ranine  artery,     ....  430 

Receptaculum  chyli,        .        .        122 

Reil's  estimate  of  heart's  force,  .  ]03 

Pectal  fascia,  ...        675 

Recto  uterine  ligament,        .        .  666 

Vesical  fascia,          .        .       675 

Rectum,       .        .        :        .        .573 

Rectus  abdominis,  .        .        .       544 

Capitis  anticus  major,  .        .  487 

Minor,     .       487 

Femoris  muscle,  .        .        .  758 

Capitis  lateralis,      .        .        .       488 

Posticus  major,        .        .  494 

Minor,    .        .       494 

Externus,      ....  350 

Inferior,   ....       350 

Internus,       » -.   •.-.*•    .    ..-.      .  350 

Superior,      v.,4  ,  •     .        .       349 

Recurrens  ulnaris,  posterior,       .  732 

Radialis,  ....       731 

Ulnaris,  (anterior,)       .        .  732 

Recurrent  nerve  of  par  vagum,      500 

Reflections  of  dura  mater,       .       395 

Regions  of  abdomen,  .        .        .  537 

Skull,     .  .215 

Regie  pubis,         ....  538 

Relations  of  cartilaginous  system,  159 

Of  fibrous  system,    .        .        156 

Mouth  and  head,      .        .  437 

Mouth  and  extremities,      785 

Mouth  and  trunk,        .       684 

Mucous  membrane,          .  140 

Organic,  .  140 

Organic  of  skin,       .        .        131 

Of  skin,        .        .        .        .130 

Renal  artery,  .        .        .        641,  627 

Capsules,  .        .        .        .641 

Plexus,.         .  .631 

Reptilia,  teeth  of,        ...  290 

Reptiles,          ....         48 

Respiratory  nerves,     .        .        .110 

Restiforme,     .        .        .        .115 


Rete  Malpighi,    .* 

Mucosunij  >:-v 
Testis,         t 

Reticular  tissue, 

Retina,  structure  of,   . 

Rhinoceros,  teeth  of, 

Rhomboid  ligament,     . 

Rhomboideum,  corpus 

Rhomboideus  major,  . 
Minor, 

Ribs,   . 

Development  of, 

Ridges  of  bones, 

Rima  glottidis, 


805 


101 

125 
652 
167 
339 
285 
703 
407 
490 
490 
463 
465 
165 
528 


Right  auricle,       .        .        .  .616 
Auriculo  ventricular  opening,  618 

Coronary  artery,      .        .  624 

Epiploic  artery,    .        .  .  563 

Lateral  ligament,      .        .  577 

Meso-colon,          .        .  .  572 

Ventricle,         ...  618 
Rodentia,  Teeth  of,     .        .  272,  282 

Rotula, 747 

Rudbeck, 38 

Ruminantia,  Teeth  of,     .        .  288 

Ruysch,  Frederick,     .    fe  .  .    38 

S. 

Sacculus  communis  of  the  ear,  .  375 

Laryngis,          .         .  532 

Proprius  of  the  ear,  .  374 

Sacral  foramina,     .        .        .  451 

Nerves,     .        *<>4t*a*  .  636 

Sacciform  ligament,         .        .  708 

Sacro  iliac  articulation,       .  .  476 

Sacro-ischial  articulation,        .  476 

Sacro-lumbalis  muscle,        .  .  492 

Sacrum,           ....  451 

Development  of,  .        .  .453 

Salernum,        ....  35 

Saliva, 302 

Salivary  glands,      •        .         .  298 

Blood-vessels  of,  .        .  .  302 

Nerves  of,        .        .        .302 

Sanctorius,  .         ...  .130 

Saphena  veins,        .        .        .  778 

Sarcolemma  of  muscles,      .  .  144 

Sartorius,        .        .        .        .  758 

Scalse  of  the  ear,        .         .  .372 

Scala  tympani,         .        .        .  372 

Vestibuli,   .        .        .  .372 

Scalenus  anticus,    .        .         .  486 

Medius,         .        .  .486 

Posticus,  ...  486 

Scales  of  epithelium,  .        .  .  135 

Scaphoides,     .       .,*  '-    *;.      .  697 

Scaphoid  fossa,    .        .     ,-*"..  .  .  361 

Cellular,  quantity  of,        .  77 

Relations  of, .  .    78 

Cutaneous,      -*    ;  ..        .  123 


806 


INDEX. 


Scapula,          ...        .        .  689 

Development  of,  .         .  .691 

Structure  of,    .        .        .  691 

Scapularis  inferior  artery,    .  .  728 

Scapulo  clavicular  articulation,      703 

Scarpa 38 

Schindylesis,        .        .        .  .152 

Schneiderian  membrane,          .  383 

Schwann, 39 

Sciatic  Nerves,         .        .       781,780 

Nerves,    ....  637 

Sclerotic  coat  of  the  eye,        .  332 

Scrobiculus  cordis,       .        .  .  538 

Scrotum,          .         .      ,  y  •      i  649 

Sebaceous  fluid,  .        .    ,. V  .129 

Glands,            .         .  129 

Secondary  convolutions  of  brain,  410 

Second  pair  of  nerves,         .  .  420 

Secretions  of  the  skin,    .         .  130 

Sella  Turcica,      .         .         .  .192 

Semicircular  canals,        s    •  -,  373 

Semilunar  cartilages,  .        .  .  754 

Ganglion,        .        .  630 

Lobe,          .        .  .405 

Valve,     .      ,V       .  619 

Semimembranosus,      i  ,\    .  .  761 

Semi  spinales  colli  muscle,     .  495 

Dorsi  muscle,  .  495 

Semitendinosus,       .        .         .  761 

Sensation,    *J.    ,.  >      . .       .  .  330 

Of  the  skin,      ...  129 

Sensibility,           .         .         .  .65 

Of  muscle,       .    .,•«:.*':    .  146 

Septum  auricularum,  ..     ••,  .  618 

Cordis,        .        .        .  621 

Lucidum,         .        .  417,  419 

Pectiniforme,      .        .  657 

Serous  tissue,       .         .        .  .80 

Form  of,  .        .         .        .  80 

Structure  of,         ...     82 

Serpents,  Teeth  of,          .        .  291 

Serrated  suture,            .         .  .152 

Serratus  major  anticus,  .        .  598 

Posticus  superior,  .  491 

Inferior,      .  492 

Serum, 71 

Seventh  pair  of  nerves,    .        .  423 

Sheath  of  arteries,       .        .  .     93 

Tendons,         .        .  154 

Shedding  of  the  teeth,          .  .  246 

Short  bones,     ....  162 

Thoracic  artery,   .        .  .  728 

Shoulder  blade,       .      ,  .  :i;.  *  689 

Shrews   (solicidae,)      .  ,      .  .  279 

Sigmoid  cavity,  greater,      /..-  ,  697 

Lesser,        .  .  696 

Flexure  of  the  colon,   .  573 

Valve,        .        .        .  .619 

Simia3, 273 

Sinus,  circular  of  Ridley,    .  .  398 

Sinuses, 166 


Sinuses,  cavernous,     .        .  •  398 

Lateral,    ....  397 

Occipital,     .         .         .  .398 

Of  the  brain,    ..        .        .  628 

Dura  mater,     .        .  •  396 

Valsalva,      ...  620 

Petrosal,        .        .        .  .398 

Sinus  frontal 173 

Inferior  longitudinal,     .  -  397 

Pocularis,          ...  659 

Superior  longitudinal,  .  .  396 

Transverse,      ...  398 

Vena  portarum,    .    ;.  <»'•  .  580 

Sixth  pair  of  nerves,       .        .  423 

Skeleton,  Artificial,     .        ..  .  162 

Natural,           .        .  162 

Division  of,  .  .162 

Skin, 123 

Papillae  of,    .         .        .  .126 

Relations  of,     .         .         .  130 

Structure  of,       •:-..;     ,.-  ;  .  125 

Skin,  Appendages  of,       .         .  132 

Skull,  general  development  of,  .  221 

Regions  of,    .         .         .  215 

Sloth,  Teeth  of,  .        .       k>;H  .  283 

Soft  palate,       ....  306 

Solar  Plexus,        .         .'       \V  .  631 

Solitary  glands,       .  .139 

Soemering,           .        .        .  .38 

Sounds  of  the  heart,        .         .  625 

Spermatic  artery,        .         .    627,  654 

Cord,  .         .         .  .653 

Spermatin,                        .        .  54 

Sphenoid  bone,    .         .  .f .  .-*  .192 

Spheno  maxillary  fissure,        .  198 

Palatine  artery,       .  .  435 

Foramen,      .  205 

Ganglion,  .  517 

Nerve,         .  266 

Sphincter  externus,     .        .  .  678 

Internus,      -.-••'    «  678 

Vaginae,        .        .  .680 

Vesicae,       *Y.%..        .  647 

Spinal  accessory  nerve,       .    424,  5l<9 

Spinalis  dorsi,         -^       •         •  493 

Spinal  marrow,    .         .         .    112,  387 

Blood-vessels  of,        .  392 

Nerves  of,      .        .  .391 

Nerves,  ganglia  of,         .  391 

Origin  of,      .    113,391 

Spine,      .         .        .       -/.   .  .  443 

Of  the  pubis,         .        .  .473 

Spines,     .....  166 

Spinous  process  of  the  ischium,  .  473 

Vertebra?,  445 

Splanchnic  nerve,        .        .  .514 

System,          .         .  116 

Spleen,         .         .         .  ..    ,    .•  .  589 

Blood-vessels  of,       .         .  590 
Function  of,           ...  590 


Lymphatics  of, 


590 


INDEX. 


807 


Spleen,  nerves  of,        ...  590 

Structure  of,    .         .         .       589 

Splenic  artery,     .        .        .   590,  627 

Plexus,     .         .        .         .631 

Splenius  capitis  et  colli,       .        .  492 

Spongy  bones,          .        .         .       207 

Squamous  epithelium,          .        .  319 

Portion  of  temporal  bone,       184 

Suture,         .        .        .        .152 

Stapedius  muscle,   ...       369 

Stapes,         .  • ...  j .•_•     .        .        .  368 

Stellate  ligament,    ...       466 

Steno'sduct,        .        .        .   226,300 

Sternal  articulation  of  the  ribs,      467 

Sterno  clavicular  articulation,     .  702 

Ligament  anterior,    .        702 

Posterior,       .  702 

Cleido  mastoideus  muscle,       482 

Hyoideus  muscle,     '••*.      .483 

Thyroideus,      ...        484 

Sternum,      .        .        .        *    '    .  460 

Development  of,       .        .       462 

Stimuli,  vital,      .        .        .        .     45 

Stomach,         .         .      ..."••".       558 

Blood-vessels  of,  .        .        .  563 

Function  of,      .        .        .        564 

Nerves  of,    .         .    •    .  '     .  563 

Structure  of,     .        .        .       560 

Striata  corpora,  .         .         .  108 

Stricture  of  mucous  membrane,     141 

Stroma, 669 

Structure  of  bone,  .        .       167 

Cartilage,  .  .  157 
Dentine,  .  .  239 
Frontal  bone,  .  180 

Mucous  membrane,    135 
Muscle,  . 
Occipital  bone,  . 
Parietal  bone, 
Teeth, 

Styloid  apophysis, 
Process, 

Of  the  radius,  . 
Stylo-glossus  muscle, 

Hyoideus  muscle,         '•  '  ' 
Hyoid  nerve,     .        .       ^  • 
Mastoid  artery,     .        ,     '   ; 
Maxillary  ligament, 
Pharyngeus  muscle, 
Sub-arachnoid  spaces, 
Clavian  artery, 

Veins,  . 

Clavius  muscle,    . 
Lingual  artery, 

Gland,     . 
Lobular  veins, 
Maxillary  ganglion 
Gland, 
Nerve, 

Mental  artery,  . 
Mucous  Layer, 


144 
184 
382 
234 
166 
186 
695 
306 
306 
329 
432 
215 
316 
399 
627 

.   509 

.  600 

430 

.  301 

583 

.  517 

.  300 
.  330 

430,  504 
.  136 


504, 


Sub-pubic  ligament,   .  478, 676 

Scapular  artery,  .  .    .  728 

Nerves,  .  .    737 

Scapularis  muscle,  .  .       711 

Substantia  perforata  anterior,      .  411 

Sudoriferous  glands,        .  .        128 

Sugar  of  milk,     .        .  .        .56 

Supercilia,       ....       354 

Superciliary  arch,        .  .        .  178 

Superficial  abdominal  fascia,  545 

Cervical  fascia,     .  .        .  522 

Circumflexa  ilii,       .  .        773 

Epigastric  artery,  .        •  773 

Superficial  colli  nerve,  .       511 

Volae  artery,         .  .        .731 

Superficial  perineal  artery,  .        680 

Superior  articular  artery,  .         .  775 

Cerebellar  arteries,  .  .       427 

Cervical  ganglia,  .         •  520 

Coronary  artery,       .  227,  431 

Costo-sternal  ligaments,  .  467 

Dental  artery,           ,  261,  434 

Extremity,    .        .  .         .689 

Ganglia  of  cerebrum,  .        416 

Intercostal  veins,  .         .  509 

Laryngeal  artery,     .  .       503 

Nerve,   .         .  .         .500 

Longitudinal  sinus,  .  179,  396 

Maxillary  bone,     .  .         .196 

Development  of,  .        203 

Foramina  of,   .  .          202 

Process  of,          .  .       202 

Structure  of,  .         .  202 

Nerve,       .        .  423,263 

Mesenteric  artery,  .        .  627 

Plexus,  .  .        631 

Musculo-cutaneous  nerve,'    .  635 

Palatine  artery,         .  .        434 

Palpebral  sinus,    .  .        .  356 

Pelvic  aponeurosis,  .  .       675 

Pharyngeal  artery,  .        .  435 

Pubic  ligament,         .  .        478 

Scapular  artery,    .  .         .  506 

Strait  of  the  pelvis,  .  .        478 

Thoracic  artery,   .  .         .  728 

Thyroid  artery,         503,  428,  429 

Turbinated  bones,  .         .  190 

Vena  Cava,       .         .  101,  628 

Vermiform  process,  .         .  405 

Supinator  radii  brevis,     .  .       719 

Longus,  .         .  717 

Supra-clavicular  nerves,  .       514 

Orbital  nerve,       .  .        .  354 

Ridge,          .  .       178 

Renal  plexus,       .  .        .  631 

Scapular  nerves,      .  .       737 

Spinalis,        .         .    '  .         .496 

Spinatus,  ....        710 

Spinous  fascia,      .  .         .  725 

Ligament,          .  .        457 

Trochlear  nerve,  .        .  353 


808 


INDEX. 


Suspensory  ligament,         .    556, 
Of  the  penis,     .        . 

576 
657 

Temporal  artery,  structure  of,     . 
Fossa,       .        .        .        *   . 

188 
193 

Sural  arteries,     .... 
Sutura,    

775 
159 

Temporalis  muscle, 
Temporal  nerve,      .      ^        ,  >' 

295 
320 

Sutures,       
Sylvius,  
Symmetrical  muscles, 
Sympathetic  nerve,          .        514, 
System,           .         « 

195 
37 
142 
629 
116 

Ridge,          •  :    W        • 
Temporary  teeth,    . 
Temporo-facial  nerve, 
Tendons,           .        .        .        147, 

181 
244 
329 
153 
396 

Symphysis,      .... 
Menti                                       . 

153 

209 

Tensor  palati, 
Tarsi,       .... 

308 
351 

Pubis,       .... 

474 

Tympani,    . 

369 

Synarthrosis,        .        .        .         . 
Syndesmology, 
Sy  no  vial  membranes,                   83 

152 
150 

Vaginae  femoris,       .     •'.* 
Tentorium,      ...        ,..;> 

758 
395 
711 

Syssarcosis,     .        .         .      •,*.>. 
Systemic  circulation,   .  •     •        • 

153 
695 

Minor,           .        .        . 

Testes,         .        .   •     . 

711 

649 

Swammerdam,        .        »      .r.  •  . 

T. 

Tactile  papilla,   ,r  v',"'';  V.  \,V> 

38 

133 
335 

Of  the  brain,    .        .       ;.    * 
Blood-vessels  of,   .    ,  ,  •        • 
Function  of,      .        .        »  ; 
Lymphatics  of,      .        .  .:,,  ,». 
Nerves  of,         .    .  \  ^  .  .»   •; 
Thalami  optici     •    '    •     •  *        V 

413 
654 
654 
654 
654 
414 

Tsenia  hippocampi,      .        .      .'!. 
Semicircularis,         .        « 
Tarsal  arteries,    .        .'      .   .     . 
Cartilages,  .         .       -.' 
Tarsus,         .        .        . 
Tartar  glands,          .        .  "    . 

417 
417 
776 
356 
748 
322 

Theca  vertebralis,  .        .        .,,. 
Third  pair  of  nerves,    ......  ;.  .,  K. 
Ventricle,      .        »,     .*,  .' 
Thoracica  acromalis  artery, 
Thoracic  duct,         .        .        121, 
Left,         .    '    , 

388 
421 
416 
728 
122 
595 

Teeth,.        .        .^  V'    .        . 

997 

Riffht 

596 

Bicuspids,         .                 , 

232 

737 

Blood-vessels, 
Canine,  or  cuspidati,         . 

259 
930 

Spinal  nerves,  .      .  •        »   , 
Thorax,        .        .        •     '  "*.        . 

632 

460 

Cavity  of  reserve,       %".        . 
Classification  of, 
Comparative  anatomy  of, 
Description  of, 
Difference  between,  and  bone, 
Temp,  and  permanent, 
Eruption  of  temporary, 
Follicular  stage  of,  . 
Functional  relations  of, 
Grand  division  of,    . 
Irregularities  of,   .        .        ', 
Molar,      .        .        .       v   ' 

251 

228 
268 
229 
247 
246 
244 
259 
258 
228 
247 
939 

Thymus  gland, 
Blood-vessels  of,    . 
Function  of, 
Lymphatics  of, 
Nerves  of,                   . 
Structure  of,        ^,, 
Thyro-arytenoideus, 
Arytenoid  ligament,      •<  :  :  , 
Epiglottideus,   .        .        • 
Ligament, 
Hyoideus,          .        .   ..   (•., 
Hyoid  ligament,    »        •    ,     . 

613 
613 
613 
613 
613 
613 
530 
528 
531 
528 
529 
597 

Nerves  of,     .         .       '  .  '      . 
Of  Mammalia,      '  '.  '      • 

262 
970 

Membrane,     .       ;»  i 

527 
506 

Oral,     
Origin  and  development  of, 
Papillary  stage  of, 
Permanent,  eruption  of,   . 
Saccular  stage  of,       .  ,'.      • 

230 
248 
250 
245 
950 

Cartilage,  .        .        .  , 
Foramen,        .         .       .. 
Gland,  arteries  of,     . 
Nerves  of, 
Tibia  

525 

474 
524 
525 

745 

Shedding  of,     .   "  V  '  "  •  ^ 
Structure  of,          .        .  "'  ". 
Varieties  of,              .    .    .    , 
Temp'l  artery,  and  branches,  429, 
Bone,  .... 
Articulation  of,  . 
Development  of,    . 
Foramina  of,  .     .        . 
Processes  of,  . 

246 
234 
258 
432 

184 
189 

188 
188 
188 

Tibialis  anticus,   .... 
Posticus,     . 
Tissue,  adipose,  quantity  of, 
Cartilaginous, 
Capillary,                        . 
Cellular, 
Continuity  of,      .        . 
Division  of,    . 
Form  of,     . 

762 
766 
79 
156 
84 
75 
77 
77 
76 

INDEX. 


809 


Tissue,  erectile,  . 

Glandular, 

Muscular, 

Nervous,      >    .    "'    « 

Osseous, 

Reticular, 

Serous,  form  of,    . 

Vascular, 
Tissues,       . 

Number  of, 

Origin  of,      . 

Physical  properties  of, 

Vital  properties  of, 
Tongue,  .... 

Blood-vessels  of,  . 

Chorion  of,       .        * 

Papillary  membrane  of, 

Periglottis  of,  . 

Nerves  of,     .        .        . 
Tonsil,     .... 

Lobe,    . 

Torcular  Herophili, 
Trab'eculae  septulae,      .        . 
Trachea, 

Blood-vessels  of,  . 

Nerves  of, 

Structure  of,         .  • . ;  ,« 
Trachelo  mastoideus,      . 
Tract  of  nervous  matter, 
Tractus  opticus, 
Tragicus  muscle, 
Tragus,   .... 
Transversalis  abdominis, 

Cervicis,    . 

Colli,    .... 

Pedis,    . 

Perineii,   . 
Transverse  colon, 

Compressors,    . 

Facial  artery, 

Fissure  of  liver, 

Ligament  of  atlas,    •     ,' 

Meso-colon, 

Perineal  artery,     . 

Process  of  vertebra, 

Sinuses, 
Transversus  auriculae, 

Perineii  artery,     .        », 
Trapezium,     .        .    -    . 
Trapezius,   .        .-       i        . 
Trapezoides,   . 
Triangles  of  the  neck, 
Triangularis  oris,     . 

Sterni,     . 

Triangular  ligament, 
Triceps  extensor  cubiti 
Tricuspid  valve, 
Trifacial  nerve,  . 
Trigemini  nerve,     . 
Trigone  vesical,  . 
Trochanter  major,  . 


676, 


.  160 

117 

.  141 

.        106 

.  161 

167 

.    80 

83 

.    63 
66 

.    63 
65 

.    65 

310,  377 

.  313 

378 

.  378 

378 

.  379 

137 

.  405 

184,  398 

.  658 

.       534 

.  536 

536 

.  534 

.       494 

.  110 

.       421 

.  363 

361 

.  543 

.      494 

494,  507 

.  768 

679 

.  573 

.        680 

227,  432 

578 

.  459 

556,  572 

.  680 

445 

.  398 

.       363 

.  680 

698 

.  488 

698 

.  484 

.       224 

.  600 

704,  707 

.  713 

619 

.  422 

.       422 

.  648 

.       744 


Trochanter  minor,       .  .  744 

Trochanters,   .>.-•«•.«*       166 
Trochlea  of  humerus,  .        .694 

Trochlearis  nerve,  .        .        353,  422 

Trochlea, 694 

True  pelvis,         .        .        .         .478 
Trunk, 443 


Blood-vessels  of, 
Nerves  of, 
Tuber- Annulare, 

Cinereum,     . 
Tubercle  of  the  radius, 
Tubercula  quadrigemini, 
Tuberculum  Loweri,  . 

Santorini,    . 
Tuberosities  of  bones, . 

Humerus, 
Ischii,  . 
Tuberosity  of  superior  maxillary 

bone,  .... 

Tubular  portion  of  the  kidney,    . 
Tubuli  seminiferi,    . 
Tubulus  centralis  modioli,   . 
Tumor  of  mucous  membrane, 
Tunica  albuginia, 

Arachnoidea, 

Function  of,    - 
Conjunctiva, 
Erythroides,     . 
Propria,       .,       . 
Ruyschiana,    . 
Vaginalis  testis,  . 
Vasculosa, 
Turbinated  bones,   . 
Tusks  of  the  elephant, 
Tympanic  artery,    . 
Nerve, 

Plexus,  .         .        .       „.„ 

Tympanum,          ....  364 

Lining  membrane  of,        .       370 


683 
.   683 

.  402 
.   412 
.  695 
108,  413 
.  617 
527 
.  165 
693 
473 


198 
640 
651 
373 
141 
651 
398 
399 
356 
650 
252 
334 
650 
651 
190 


341 


433 
329 
376 


u. 


Ulna,  .... 
Capsular  ligament, 
Development  of,  . 
Structure  of,    . 
Ulnar  artery, 

Nerve,  . 
Umbilical  Fissure, 

Ligament, 
Region, 
Vein,       . 
Umbilicus,  . 
Unciforme  bone,      .^ 
Unguiforme  bones, 
Urachus, 

Urea,   .         .   >     ^     , 
Ureters,    .     •   .     •   ,  * 
Urethra  female,  .        , 
Urethra  male,          . 
Uric  acid,    .     "  .        . 


696 
706 
697 
697 
732 
740 
578 
645 
537 
581 
541 
699 
206 
645 

55 
643 
663 
658 

56 


810 


INDEX. 


Uterine  arteries,    >.      M,        •.       668 

Uterus, 665 

Blood-vessels  of,  .  .  668 
s  Function  of,  ...  669 
Lymphatics  of,  .  .  668 
Nerves  of,  .  .  .  .  668 
Structure  of,  .  •  .  -  ,  667 

Uvea, .  337 

Uvula,     .        .     ....-•*       406 

V. 

Vagina,      ....     160,  664 

Structure  of,     .     ,'.    -  .       665 

Vaginal  ligament,         .         .         .  726 

Plexus,     .         .     ,.:•>;.       583 

Valley  fissure,      .         .         .         .404 

Valve  of  Eustachius,       .        .       617 

Thebesius,    .         .         .618 

Vieussens,        .        407,  414 

Valvula  Conniventes,  .         .         .  566 

Varieties  of  muscular  contraction ,  146 

Vasabrevia,         .        .        .         .563 

Efferentia,       .         .        120,  591 

Inferentia,  .        .   120,  591 

Vasorum,        ...         93 

Vascular  tissue,  .         .         .         .83 

Vasculum  aberrans,         .        .       653 

Vas  deferens,       ....  653 

Vastus  externus,      .        .' ••-. ..k       759 

Internus,  ....  759 

Vegitations  of  mucous  membrane,  141 

Vein  of  Galen,    .        .  .,,  -.  '      .  397 

Popliteal,       .    .  iti   .        .        100 

Veins  of  bones,   .        .        .        .170 

Of  inferior  extremity,      .       778 

Of  the  neck,         .         .         .507 

Of  superior  extremity,     .       735 

Valves  of,     .         .         .         .93 

Velum  interpositum,        .        414,  418 

Palati, 307 

Vena  Galeni,  ....        397 

Innominata,  ....  508 

Portarum,         ...        580 

Salvalella,     .         .         .        .735 

Venae  cav»  hepaticse,      .        .        581 

Venous  circulation,      .         .         .99 

Venter  of  the  ilium,        .         .       471 

Ventricle  of  Morgagni,        .         .  532 

Ventricles,  lateral,       ,  ;.>      .       4J7 

Ventriculus,         ....  558 

Vertebrae,        ....       443 

Cervical,       .         .        .         .  446 

Dorsal,     .         .     ,  ,.        .       449 

False,    .        ;.     S   -     .         .443 

;       Lumbar,   .        .       V      .       450 

Pelvic,  '.     '  •'.        .'       .  451 

True,       .        /       /    .     .       443 


Vertebra  prominens,  .  .  .  448 
Vertebral  artery,  .  .  426,  505 
Column,  ....  443 
Sinuses,  .  .  '  .  .388 

Vein, 509 

Vertebrata,  principal  divisions  of,  48 
Vertebro  sternal  ribs,  .  .  .  463 
Vesalius,  .  v  .  36 

Vesical  fascia,  .  .  .  .675 
Triangle,  •  .  .  .  648 
Vesica  urinaria,  .  .  .  643 

Vesico-uterine  ligaments,  .  666 
Vesiculae  seminales,  .  .  .  655 
Vessels,  lymphatic,  .  .  121 
Veru  montanum,  .  .  .  659 
Vibrisse  of  the  nose,  .  -  381 
Vidian  canal,  .  .  .  .193 
Nerve,  .  .  265,  328,  376 

Villi 566 

Of  the  intestines,      .        .       136 

Villous  coat,        ....  561 

Vitreous  humor,      .         .         .       345 

Analysis  of,  ...  345 

Blood-vessels  of,       .  345 

Voluntary  muscles,      .         .         .  142 

Vomer, 208 

Articulation  of,  .         •  208 

Development  of,       .        •        208 

Structure  of,         ...  208 

Vulva, 662 

w. 

Walls  of  abdomen,  .  .  .  539 
Weasel,  teeth  of,  .  .  .  282 
Wharton's  duct,  .  .  .  .301 
White  fibrous  tissue,  .  .  149 
Winslow,  .  .  .  .  .38 
Wirtsungius,  ....  38 

Wistar, 39 

Wrisberg,  nerves  of,  .  .  633 
Wrist, 697 

X. 

Xiphoid  cartilage,        .        .        .  462 

Y. 

Yellow  fibre,  elasticity  of,  .  .  149 
Fibrous  tissue,  .  .  149 
Ligaments,  ....  456 

z. 

Zygomatic  fossa,      .  .        .  .193 

Process,  ./,-'.  206 

Zygomaticus  major,  .        .  .  225 

Minor,        .        .  225 

Zonula  ciliaris,    .  .-.-..  •  340 


RETUR 


14  DAY  USE 

ETURN  TO  DESK  FROM  WHICH  BORROWED 


This  book  i^cJne^rr  die  last^t^^a«i?e^  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


.tflM      3  Iflftl 


LD  21-50m-6,'59 
(A2845slO)476 


General  Library 

University  of  California 

Berkeley 


Hi 


